CB is thankful for his Future Fellowship from Australian Research Council (ARC-FT12010096) and UNSW Australia.

1. Synthesis and Characterization of POEGMA Macro-CTA
<ol>
	<li>Add oligo(ethylene glycol) methyl ether methacrylate (OEGMA) (12 g, 4 &#215; 10-2 mol), 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CPADB) (0.224 g, 8 &#215; 10-4 mol), 2,2&#8242;-azobis(2-methylpropionitrile) (AIBN) (16.4 mg, 0.1 mmol) and 50 ml acetonitrile (MeCN) to a 100 ml round bottom flask.</li>
	<li>Seal the flask with an appropriately sized rubber septum and steel wire and cool the flask from room temperature to &#60; 4 &#176;C in an ice-water bath.</li>
	<li>Deoxygenate the flask for 30 min by bubbling nitrogen directly into the reaction mixture through a 21 G needle (0.8 mm x 120 mm) with a second 21 G needle (0.8 mm x 38 mm) acting as a vent.</li>
	<li>Place the flask in an oil bath at 70 &#176;C for 5.5 hr before quenching the polymerization by immersion in an ice-water bath and exposing the contents to air.</li>
	<li>Remove the MeCN by agitation under a continuous stream of compressed air and re-dissolve the crude mixture in ~40 ml tetrahydrofuran (THF).</li>
	<li>Add the contents of the flask dropwise to 400 ml of a rapidly stirred mixture of petroleum spirits (b.p. 40-60 &#176;C) and diethyl ether (70:30, v/v) and continue to stir until the supernatant is no longer cloudy. 
	Note: Cooling in an ice-bath may be used to accelerate the precipitation process.</li>
	<li>Decant the supernatant and re-dissolve the polymer residue in ~40 ml THF.</li>
	<li>Repeat the precipitation process (steps 1.5-1.7) at least two more times to ensure complete removal of the residual OEGMA monomer. Remove the excess solvent from the purified POEGMA macro-CTA firstly by agitation under a continuous stream of compressed air and drying in a vacuum oven (20 &#176;C, 10 mbar) for 4 hr.</li>
	<li>Determine the number average molecular weight of the POEGMA macro-CTA by Nuclear Magnetic Resonance (NMR) (Mn, NMR) using a previously reported method15. Using gel permeation chromatography15 (GPC) (dimethylacetamide as mobile phase and appropriate standards for calibration) calculate the polymer dispersity (&#208;). 
	Note: Using the above synthesis (steps 1.1-1.8) should yield a POEGMA macro-CTA with Mn, NMR = 9,000, and &#208; &#60; 1.15. If the molecular weight (and dispersity) of the synthesized POEGMA macro-CTA differs from the synthesis presented here (between 7,000 - 1,000 g/mol), the formation of worm-like micelles (as indicated by in situ gelation) can still occur using the subsequent PISA methodology presented in (section 2) albeit at a slightly altered reaction time.</li>
</ol>
2. Preparation of POEGMA-b-PBzMA Nanoparticles Using PISA
<ol>
	<li>Prepare a 1 mg/ml stock solution of Ru(bpy)3Cl2 .6H2O in ethanol (EtOH). Store the stock solution in the refrigerator to minimize solvent evaporation.</li>
	<li>Plug a Pasteur pipette with a small wad of cotton wool using a second pipette to help pack it tightly. Pour basic aluminum oxide into the pipette with the cotton wool plug to give a column of approximately 5 cm. Remove the monomethyl ether hydroquinone inhibitor in commercial BzMA by passing ~3 ml of BzMA through the column and collecting the deinhibited BzMA eluent.</li>
	<li>Add POEGMA macroCTA (~9,000 g/mol; 76.9 mg, 8.5 &#215; 10-6 mol), deinhibited BzMA (0.301 g, 1.71 &#215; 10-3 mol), Ru(bpy)3Cl2.6H2O (128 &#181;g, 1.71&#215;10-7 mol, 128 &#181;l of a 1 mg/ml ethanolic stock solution), 0.383 ml MeCN and 1.402 ml EtOH (1.913 ml total solvent, 80 wt%, 20 v/v% MeCN) to a 4 ml glass vial.</li>
	<li>Perform the deoxygenation procedure as outlined in steps 1.2-1.3.</li>
	<li>Place the vial in a 2,000 ml glass beaker (Figure 2) lined with blue LED strips (&#955;max = 460 nm, 0.7 mW/cm2) and irradiate at room temperature with magnetic stirring. Monitor the reaction vial routinely after 20 hr and remove it from the reactor when the high viscosity solution forms a free standing gel when the vial is inverted (Figure 3). 
	Note: The total time to yield a free-standing gel should be about 24 hr of blue light irradiation using the conditions presented here. Small differences in the light irradiation reactors (physical dimensions, intensity, etc.) may require slightly altered conditions (specifically reaction time) to achieve the in situ formation of worm-like micelles.</li>
	<li>After removing from the reactor, quench the polymerization by exposing the nanoparticle gel to air for a few minutes and storing the closed vial upright in the dark.</li>
</ol>
3. Transmission Electron Microscopy (TEM) Imaging of Nanoparticle Morphology
<ol>
	<li>Place approximately 40 mg of the crude nanoparticle gel (from section 2) in a 4 ml glass vial.</li>
	<li>Continuously agitate the nanoparticle gel using a vortex mixer and add 4 ml of EtOH dropwise over a period of at least 5 min. The gel should become a free-flowing solution during the solvent addition. 
	Note: If the gel is diluted with EtOH too rapidly or not agitated adequately, some precipitation of the nanoparticles may occur. See step 3.3.</li>
	<li>Remove any macroscopic aggregates from the diluted nanoparticles by filtering through glass wool.</li>
	<li>Perform TEM imaging (with uranyl acetate staining) of the diluted sample according to a previously reported procedure.15</li>
</ol>

<ol>
	<li>Yu, Y., Eisenberg, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+Morphology+through+Polymer&#8722;Solvent+Interactions+in+Crew-Cut+Aggregates+of+Amphiphilic+Block+Copolymers.">Control of Morphology through Polymer&#8722;Solvent Interactions in Crew-Cut Aggregates of Amphiphilic Block Copolymers.</a> J. Am. Chem. Soc. 119 (35), 8383-8384 (1997).</li><li>Zhang, L., Eisenberg, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermodynamic+vs+Kinetic+Aspects+in+the+Formation+and+Morphological+Transitions+of+Crew-Cut+Aggregates+Produced+by+Self-Assembly+of+Polystyrene-b-poly(acrylic+acid)+Block+Copolymers+in+Dilute+Solution.">Thermodynamic vs Kinetic Aspects in the Formation and Morphological Transitions of Crew-Cut Aggregates Produced by Self-Assembly of Polystyrene-b-poly(acrylic acid) Block Copolymers in Dilute Solution.</a> Macromolecules. 32 (7), 2239-2249 (1999).</li><li>Zhang, L., Eisenberg, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiple+Morphologies+of+'Crew-Cut'+Aggregates+of+Polystyrene-b-poly(acrylic+acid)+Block+Copolymers.">Multiple Morphologies of 'Crew-Cut' Aggregates of Polystyrene-b-poly(acrylic acid) Block Copolymers.</a> Science. 268 (5218), 1728-1731 (1995).</li><li>Yu, K., Zhang, L., Eisenberg, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+Morphologies+of+&amp;#34;Crew-Cut&amp;#34;+Aggregates+of+Amphiphilic+Diblock+Copolymers+in+Dilute+Solution.">Novel Morphologies of &amp;#34;Crew-Cut&amp;#34; Aggregates of Amphiphilic Diblock Copolymers in Dilute Solution.</a> Langmuir. 12 (25), 5980-5984 (1996).</li><li>Blanazs, A., Ryan, A. 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Soc. 135 (36), 13574-13581 (2013).</li><li>Sugihara, S., Blanazs, A., Armes, S. P., Ryan, A. J., Lewis, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aqueous+Dispersion+Polymerization:+A+New+Paradigm+for+in+Situ+Block+Copolymer+Self-Assembly+in+Concentrated+Solution.">Aqueous Dispersion Polymerization: A New Paradigm for in Situ Block Copolymer Self-Assembly in Concentrated Solution.</a> J. Am. Chem. Soc. 133 (39), 15707-15713 (2011).</li><li>Wan, W. M., Hong, C. Y., Pan, C. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-pot+synthesis+of+nanomaterials+via+RAFT+polymerization+induced+self-assembly+and+morphology+transition.">One-pot synthesis of nanomaterials via RAFT polymerization induced self-assembly and morphology transition.</a> Chem. Comm. (39), 5883-5885 (2009).</li><li>Semsarilar, M., Jones, E. R., Blanazs, A., Armes, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+Synthesis+of+Sterically-Stabilized+Nano-Objects+via+RAFT+Dispersion+Polymerization+of+Benzyl+Methacrylate+in+Alcoholic+Media.">Efficient Synthesis of Sterically-Stabilized Nano-Objects via RAFT Dispersion Polymerization of Benzyl Methacrylate in Alcoholic Media.</a> Adv. Mater. 24 (25), 3378-3382 (2012).</li><li>Karagoz, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymerization-Induced+Self-Assembly+(PISA)+-+control+over+the+morphology+of+nanoparticles+for+drug+delivery+applications.">Polymerization-Induced Self-Assembly (PISA) - control over the morphology of nanoparticles for drug delivery applications.</a> Polym. Chem. 5 (2), 350-355 (2014).</li><li>Geng, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape+effects+of+filaments+versus+spherical+particles+in+flow+and+drug+delivery.">Shape effects of filaments versus spherical particles in flow and drug delivery.</a> Nat Nano. 2 (4), 249-255 (2007).</li><li>Blanazs, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sterilizable+gels+from+thermoresponsive+block+copolymer+worms.">Sterilizable gels from thermoresponsive block copolymer worms.</a> J. Am. Chem. Soc. 134 (23), 9741-9748 (2012).</li><li>Pei, Y., Thurairajah, L., Sugita, O. R., Lowe, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RAFT+Dispersion+Polymerization+in+Nonpolar+Media:+Polymerization+of+3-Phenylpropyl+Methacrylate+in+n-Tetradecane+with+Poly(stearyl+methacrylate)+Homopolymers+as+Macro+Chain+Transfer+Agents.">RAFT Dispersion Polymerization in Nonpolar Media: Polymerization of 3-Phenylpropyl Methacrylate in n-Tetradecane with Poly(stearyl methacrylate) Homopolymers as Macro Chain Transfer Agents.</a> Macromolecules. 48 (1), 236-244 (2015).</li><li>Fielding, L. A., Lane, J. A., Derry, M. J., Mykhaylyk, O. O., Armes, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermo-responsive+Diblock+Copolymer+Worm+Gels+in+Non-polar+Solvents.">Thermo-responsive Diblock Copolymer Worm Gels in Non-polar Solvents.</a> J. Am. Chem. Soc. 136 (15), 5790-5798 (2014).</li><li>Yeow, J., Xu, J., Boyer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymerization-Induced+Self-Assembly+Using+Visible+Light+Mediated+Photoinduced+Electron+Transfer-Reversible+Addition-Fragmentation+Chain+Transfer+Polymerization.">Polymerization-Induced Self-Assembly Using Visible Light Mediated Photoinduced Electron Transfer-Reversible Addition-Fragmentation Chain Transfer Polymerization.</a> ACS Macro Lett. 4 (9), 984-990 (2015).</li><li>Xu, J., Jung, K., Corrigan, N. A., Boyer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aqueous+photoinduced+living/controlled+polymerization:+tailoring+for+bioconjugation.">Aqueous photoinduced living/controlled polymerization: tailoring for bioconjugation.</a> Chem. Sci. 5 (9), 3568-3575 (2014).</li><li>Pei, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RAFT+dispersion+polymerization+of+3-phenylpropyl+methacrylate+with+poly[2-(dimethylamino)ethyl+methacrylate]+macro-CTAs+in+ethanol+and+associated+thermoreversible+polymorphism.">RAFT dispersion polymerization of 3-phenylpropyl methacrylate with poly[2-(dimethylamino)ethyl methacrylate] macro-CTAs in ethanol and associated thermoreversible polymorphism.</a> Soft Matter. 10 (31), 5787-5796 (2014).</li></ol>

The authors have nothing to disclose.

This visualized protocol demonstrates the ability to monitor the formation of worm-like micelles simply by observing the onset of gel-like behavior. The utility of this approach lies in the ability to monitor worm formation during the polymerization in comparison to other methods. This procedure can be performed using a two-step polymerization of two commercially available monomers (OEGMA and BzMA) to yield self-assembled POEGMA-b-PBzMA amphiphilic diblock copolymers.
It should be noted here that reactors with different reactor geometries, light intensities, etc., compared to those in Figure 2 may require slightly altered conditions to yield worm-like micelle gels. Due to the absorption characteristics of the ruthenium-based catalyst, polymerization can only occur at a reasonable rate under blue visible light. In principle, other catalysts with different light absorption properties could also be used. Care should be taken to not leave the worm gels in the reactor too long otherwise macroscopic precipitates may begin to form. This occurs as the nanoparticles attempt to reorganize into vesicular structures but are inhibited by the highly viscous medium. In some cases, we have observed the formation of partial vesicles (jellyfish or octopi structures) via TEM imaging when the polymerization was kept in the reactor beyond the first observation of a free-standing gel-like state.
To increase the accessibility of this technology, the PET-RAFT PISA polymerizations reported in this protocol were performed at room temperature without external temperature regulation (cooling fan, water bath etc.). Additionally, the low wattage LED strips do not generate observable increases in the vial temperatures during the course of the polymerization (less than 5 &#176;C). Whilst it is well known that the polymerization rate has a strong dependence on temperature, inhibition of the ability of worm-like micelles to induce macroscopic gel-like behavior even when polymerizing at 50 &#176;C has not been observed.
Obtaining shorter worm-like micelles (on average) is also possible by removing the light source before the reaction medium has reached a free-standing state but has a noticeable increase in viscosity. This approach may be favorable since dilution of these &#34;softer&#34; gels (without precipitation) for analysis is significantly easier compared to the free-standing gels. In a similar manner, spherical micelles may be obtained by reducing the irradiation time even further; typically after the first onset of cloudiness during the polymerization.
In principle, a range of different solvophillic monomers could be used instead of OEGMA (e.g., poly(2-hydroxyethyl methacrylate), poly(methacrylic acid) however some optimization of the polymerization kinetics and self-assembly parameters would be required. A high livingness of the homopolymerization of the macro-CTA should be demonstrated in order to increase the efficiency of the subsequent PISA polymerization. However, as long as a sufficiently pure worm-like micelle phase exists during the course of the polymerization, gelation can still occur. The utility of the presented approach lies in the fact that different length macro-CTA stabilizers can be used without the need to significantly reoptimize the procedure for forming worm-like micelles. In this protocol, the POEGMA macro-CTA was synthesized using a thermally initiated RAFT protocol however, we have also demonstrated the ability to generate POEGMA with high chain-end fidelity using a homogenous PET-RAFT protocol16. Although structurally similar monomers to BzMA have also been reported to form worm-like micelle gels17, it is likely that only a limited number of monomers are able to undergo controlled radical dispersion polymerization to yield worm-like micelles with significant gelation properties.
Although different reactor setups (including reaction vial geometry) can result in varying polymerization rates in most photopolymerization systems, the ability to visually monitor the in situ formation of worm-like micelles helps overcome this limitation when using a PET-RAFT PISA approach. As a result, the polymerization time can be altered depending on the precise reactor setup implemented. It is well known that the worm-like micelle phase can be difficult to produce in high purity and yield, however in the presented approach we are able to produce worm-like particles at a solids content &#62; 10 wt%. Importantly, the formation of these particles can be monitored during the polymerization rather than previous reports whereby worm-like micelle synthesis can only be confirmed after quenching the polymerization and performing ex situ TEM imaging.
Importantly, the ability to reproducibly generate these high aspect ratio nanoparticles at high solids content has important implications for a number of applications particularly in the biological arena as drug delivery carriers. A number of studies have demonstrated the interesting behavior of non-spherical morphologies in biological environments such as an increased blood circulation time compared to their spherical counterparts11 or varying cell-uptake behavior10. Whilst these particles are synthesized in ethanolic solution, we have previously demonstrated that under appropriate dialysis conditions the morphology of these PISA nanoparticles can be retained in aqueous solution10. The advantage of this approach lies in the ability to firstly encapsulate poorly water soluble therapeutics under ethanolic dispersion conditions before dialysis into water for biological study. In addition, it is likely that these elongated particles exhibit varied cell uptake behavior relative to spherical structures due to their virus-like morphologies.

The synthesis of nonspherical (and other) nanoparticle morphologies has traditionally been accomplished using a multistep self-assembly procedure starting with the synthesis and purification of well-defined amphiphilic diblock (or multiblock) copolymers. One of the most common self-assembly techniques was popularized by Eisenberg in the 1990s and involves the dissolution of the amphiphilic block copolymer in a common solvent for both polymer blocks followed by the slow addition of a solvent selective for one of the blocks1-3. As the selective solvent (typically water) is added, the block copolymer undergoes self-assembly to form polymeric nanoparticles. The final morphology (or mixtures of morphologies) of the nanoparticles are determined by a large number of factors such as the relative lengths of each polymer block, rate of water addition and the nature of the common solvent. However, this approach generally only allows for the production of nanoparticles at relatively low solids content (less than 1 wt%) and so limits its practical scalability4. In addition, the reproducible formation of &#34;intermediate&#34; phases such as worm-like micelles can be difficult owing to the narrow range of parameters required to stabilize this nonspherical morphology5.
The polymerization-induced self-assembly (PISA) approach partially addresses the drawbacks of the Eisenberg approach by utilizing the polymerization process itself to drive self-assembly in situ allowing for nanoparticle synthesis at much higher solids content (typically 10-30 wt%)6-8. In a typical PISA approach, a living polymerization process is used to chain extend a solvent soluble macroinitiator (or macro-CTA) with a monomer that is initially soluble in the reaction medium but forms an insoluble polymer. The PISA approach has been used to synthesize worm-like micelles by systematically testing a number of experimental parameters and using detailed phase diagrams as a synthetic &#34;roadmap&#34;5,9.
Despite their challenging synthesis, there is great interest in worm-like nanoparticles due to their interesting properties relative to their spherical counterparts. For example, we have demonstrated that drug loaded short and long worm-like micelles synthesized using a PISA approach have significantly higher in vitro cytotoxicity compared to spherical micelles or vesicles10. Others have shown a correlation between nanoparticle aspect ratio and blood circulation time in in vivo models11. Others have shown that the synthesis of worm-like nanoparticles using an appropriate PISA methodology yields a macroscopic gel due to the nanoscale entanglement of the nanoparticle filaments. These gels have demonstrated potential as sterilizable gels owing to their thermoreversible sol-gel behavior12.
This protocol describes a method allowing for the in situ monitoring of the formation of worm-like micelles by simply observing the solution viscosity during the polymerization. Previous studies of similar worm-like micellar gels have demonstrated that above a critical temperature, these nanoparticles undergo a reversible worm-sphere transition and so form free-flowing dispersions at elevated temperatures. To date, these systems have utilized a thermally sensitive azo compound to initiate the controlled polymerization13,14 and so gelation may not be readily observed in these systems during the thermal polymerization. From these studies, it was hypothesized that synthesizing PISA derived nanoparticles at lower temperatures may allow for observation of this gelation behavior in situ.
Recently we reported the use of a facile room temperature photopolymerization technique to mediate the PISA process to yield nanoparticles of different morphologies15. Here, a visualized protocol is presented for the reproducible synthesis of worm-like micelles by observing the solution viscosity behavior during the polymerization. The dispersion polymerization proceeds readily using commercially available light-emitting diodes (LEDs) (&#955; = 460 nm, 0.7 mW/cm2).

<table><tbody><tr><td>4-Cyano-4-&lt;br /&gt;(phenylcarbonothioylthio)pentanoic acid (CPADB)</td><td>Sigma-Aldrich</td><td>722995-5G</td><td></td></tr><tr><td>Oligo(ethylene glycol) methyl ether methacrylate (OEGMA)</td><td>Sigma-Aldrich</td><td>447935-500ML</td><td>Average M&lt;sub&gt;n&lt;/sub&gt; 300, contains 100&amp;nbsp;ppm MEHQ as inhibitor, 300&amp;nbsp;ppm BHT as inhibitor</td></tr><tr><td>2,2&amp;prime;-Azobis(2-methylpropionitrile) (AIBN)</td><td>Sigma-Aldrich</td><td></td><td></td></tr><tr><td>Ru(bpy)&lt;sub&gt;3&lt;/sub&gt;Cl&lt;sub&gt;2&lt;/sub&gt;.6H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma-Aldrich</td><td>544981-1G</td><td></td></tr><tr><td>Benzyl methacrylate (BzMA)</td><td>Sigma-Aldrich</td><td>409448-1L</td><td>Contains monomethyl ether hydroquinone as inhibitor</td></tr><tr><td>Aluminium oxide (basic)</td><td>Chem-Supply Pty Ltd Australia</td><td>AL08371000</td><td></td></tr><tr><td>95% Ethanol (EtOH)</td><td>Sucrogen Bio Ethanol</td><td>80889</td><td></td></tr><tr><td>Acetonitrile (MeCN)</td><td>Chem-Supply Pty Ltd Australia</td><td>RP1005-G2.5L</td><td></td></tr><tr><td>Tetrahydrofuran (THF)</td><td>Chem-Supply Pty Ltd Australia</td><td>TA011-2.5L</td><td></td></tr><tr><td>Petroleum Spirits (40-60&amp;nbsp;&amp;#176;C)</td><td>Chem-Supply Pty Ltd Australia</td><td>PA044-2.5L</td><td></td></tr><tr><td>Diethyl Ether</td><td>Chem-Supply Pty Ltd Australia</td><td>EA0362.5L</td><td></td></tr><tr><td>Dimethylacetamide (DMAc)</td><td>VWR International Australia</td><td>ALFA22916.M1</td><td>For GPC analysis</td></tr><tr><td>Pasteur pipettes (230&amp;nbsp;mm)</td><td>Labtek</td><td>355.050.503</td><td></td></tr><tr><td>Glass beakers</td><td>Labtek</td><td>025.01.902 (2L)/ 2110654 (1L)</td><td>2&amp;nbsp;L beaker is for attaching LED strips to form the circular reactor</td></tr><tr><td>Commercial LED strip</td><td>EcoLab</td><td>n/a</td><td>&amp;lambda; = 460 nm, 4.8 W/m</td></tr><tr><td>4 ml Glass Vials</td><td>Labtek</td><td>APC502214B</td><td></td></tr><tr><td>0.9 ml Quartz Cuvette</td><td>Starna Scientific Ltd</td><td>21/Q/2</td><td></td></tr><tr><td>Needle (0.8 mm x 38&amp;nbsp;mm)</td><td>Beckton Dickson</td><td>302017</td><td>For deoxygenating reactions</td></tr><tr><td>Needle (0.8 mm x 120&amp;nbsp;mm)</td><td>B Braun Australia</td><td>4665643</td><td>For deoxygenating reactions</td></tr><tr><td>Sleeve stopper septa (rubber septum)</td><td>Sigma-Aldrich</td><td>z564680/z564702</td><td></td></tr><tr><td>Stirring hotplates</td><td>VWR International Australia/In Vitro Technologies</td><td>97018-488/RADRR91200</td><td></td></tr><tr><td>Vortex mixer</td><td>VWR International Australia</td><td>412-0098</td><td></td></tr><tr><td>Vacuum oven</td><td>In Vitro Technologies</td><td>MEMVO200</td><td></td></tr></tbody></table>

facile synthesis of worm-like micelles by visible light mediated dispersion polymerization using photoredox catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

In this study, two-step polymerization protocol is used for the synthesis of worm-like micelles using a PISA approach (Figure 1). In the first step, the polymerization of OEGMA is performed yielding a POEGMA macro-CTA which can be used as a stabilizer in the subsequent polymerization step. The PET-RAFT polymerization proceeds under dispersion conditions owing to the insolubility of PBzMA in ethanol which ultimately leads to nanoparticle formation. During the polymerization, the initially transparent reaction mixture can be observed to become cloudy in accordance with a dispersion polymerization and eventually transitions to a highly viscous gel-like state indicating the formation of worm-like micelles (Figure 3). Indications of a &#34;living&#34; polymerization are apparent (Figure 1A) with low polymer dispersities (&#208; &#60; 1.3) and a good correlation between the molecular weight and monomer conversion. In addition, GPC traces (Figure 1B) indicate a predominantly unimodal distribution with varying conversion although some high molecular termination and low molecular weight tailing is observed in this system. Importantly, these &#34;dead&#34; polymer chains are not at a sufficient quantity to inhibit the formation of pure worm-like micelles. The shift of the molecular weight distribution with increasing conversion suggests the predominant formation of POEGMA-b-PBzMA diblock copolymers with a narrow distribution of chain lengths.
Figure 2A illustrates the light reactor setup used in this experiment in which a 1 meter commercial LED strip (&#955; = 460 nm, 4.8 W/m) is wound inside 2 L beaker. In our experiments, it was also determined that a household lamp with a similar blue light intensity (Figure 1B) could also be used in the PET-RAFT PISA process.
Figure 4 demonstrates that the formation of the worm-like micelle morphology is also achievable under different reaction conditions such as variable vial types and reagent compositions but also if the light source is applied in an intermittent fashion. This implies that despite the strong effect of light penetration on polymerization rates in most photopolymerization systems, the gelation behavior in the PET-RAFT PISA protocol can still be used as a reliable indicator for worm-like micelle formation. This is an important result since typically ex situ TEM imaging is required to provide evidence of worm-like micelle formation. Apart from the observed gelation behavior, formation of purely worm-like micelles should be confirmed by observing the morphology of a significant amount of nanoparticles (&#62; 100) by TEM (with uranyl acetate staining). If partial vesicle morphologies are observed, the irradiation time should be decreased; conversely if spherical micelles are observed then irradiation time should be increased slightly.
<img alt="Figure 1" src="/files/ftp_upload/54269/54269fig1.jpg" /> 
Figure 1. Reaction scheme for synthesizing worm-like micelles using PET-RAFT, a living photopolymerization technique. (Above) Two step approach for the synthesis of worm-like micelles using a PISA approach. (Below) Kinetic study demonstrating (A) the evolution of molecular weight and polymer dispersity during the PISA polymerization and (B) the evolution of the molecular weight distribution from gel permeation chromatography (GPC) with conversion. Adapted with permission from ref15. Copyright (2015) American Chemical Society. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54269/54269fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/54269/54269fig2.jpg" /> 
Figure 2. Digital photographs of different visible light reactors. (A) The circular reactor used in this study lined with blue LED strips (&#955;max = 460 nm, 0.7 mW/cm2). (B) A household lamps fitted with a 5 W bulb that can also be used in this protocol. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54269/54269fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/54269/54269fig3.jpg" /> 
Figure 3. Representative digital photographs of a PET-RAFT mediated PISA polymerization. Images were taken (A) before polymerization, (B) after 15 hours and (C) after 24 hours of visible light irradiation. During the polymerization, the initially transparent reaction mixture becomes cloudy and eventually transitions to a free-standing gel state indicative of the in situ formation of worm-like micelles. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54269/54269fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" src="/files/ftp_upload/54269/54269fig4.jpg" /> 
Figure 4. Characterization and TEM images of POEGMA-b-PBzMA diblock copolymers formed using a PET-RAFT PISA approach yielding worm-like micelles. TEM images (and digital photograph inserts) of worm-like micelles formed using different polymerization conditions. (A) and (C) were illuminated for 24 hours whereas (B) required a total ON/OFF irradiation time of 39 hours before gelation (when using a 10,000 g/mol POEGMA macro-CTA). In each case, a high viscosity gel is formed which is characteristic of the formation of worm-like micelles. Adapted with permission from ref15. Copyright (2015) American Chemical Society. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54269/54269fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst at JoVE.com

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

facile-synthesis-worm-like-micelles-visible-light-mediated-dispersion

Nanyang Technological University

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JoVE Journal

Chemistry

9.5K Views.  The University of New South Wales. This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

Video: Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

A Facile and Efficient Approach for the Production of Reversible Disulfide Cross-linked Micelles

Nanomedicine is an emerging form of therapy that harnesses the unique properties of particles that are nanometers in scale for biomedical application. Improving drug delivery to maximize therapeutic outcomes and to reduce drug-associated side effects are some of the cornerstones of present-day nanomedicine. Nanoparticles in particular have found a wide application in cancer treatment. Nanoparticles that offer a high degree of flexibility in design, application, and production based on the tumor microenvironment are projected to be more effective with rapid translation into clinical practice. The polymeric micellar nano-carrier is a popular choice for drug delivery applications.
In this article, we describe a simple and effective protocol for synthesizing drug-loaded, disulfide cross-linked micelles based on the self-assembly of a well-defined amphiphilic linear-dendritic copolymer (telodendrimer, TD). TD is composed of polyethylene glycol (PEG) as the hydrophilic segment and a thiolated cholic acid cluster as the core-forming hydrophobic moiety attached stepwise to an amine-terminated PEG using solution-based peptide chemistry. Chemotherapy drugs, such as paclitaxel (PTX), can be loaded using a standard solvent evaporation method. The O2-mediated oxidation was previously utilized to form intra-micellar disulfide cross-links from free thiol groups on the TDs. However, the reaction was slow and not feasible for large-scale production. Recently, an H2O2-mediated oxidation method was explored as a more feasible and efficient approach, and it was 96 times faster than the previously reported method. Using this approach, 50 g of PTX-loaded, disulfide cross-linked nanoparticles have been successfully produced with narrow particle size distribution and high drug loading efficiency. The stability of the resulting micelle solution is analyzed using disrupting conditions such as co-incubation with a detergent, sodium dodecyl sulfate, with or without a reducing agent. The drug-loaded, disulfide cross-linked micelles demonstrated less hemolytic activity when compared to their non-cross-linked counterparts.

To deliver cancer drugs to tumor sites with high specificity and reduced side effects, new methods based on nanoparticles are required. Here, we describe disulfide cross-linked micelles that can be easily prepared by hydrogen peroxide-mediated oxidation and are able to dissociate efficiently under a reducing tumor environment to release payloads.

Nanomedicine is an emerging form of therapy that harnesses the unique properties of particles that are nanometers in scale for biomedical application. ...

Biochemistry

A 'Plug and Play' Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles

In this protocol, we first describe a procedure to synthesize lanthanide doped upconverting nanoparticles (UCNPs). We then demonstrate how to generate amphiphilic polymers in situ, and describe a protocol to encapsulate the prepared UCNPs and different organic dye molecules (porphyrins and diarylethenes) using polymer shells to form stable water-dispersible nanoassemblies. The nanoassembly samples containing both the UCNPs and the diarylethene organic dyes have interesting photochemical and photophysical properties. Upon 365 nm UV irradiation, the diarylethene group undergoes a visual color change. When the samples are irradiated with visible light of another specific wavelength, the color fades and the samples return to the initial colorless state. The samples also emit visible light from the UCNPs upon irradiation with 980 nm near-infrared light. The emission intensity of the samples can be tuned through alternate irradiation with UV and visible light. Modulation of fluorescence can be performed for many cycles without observable degradation of the samples. This versatile encapsulation procedure allows for the transfer of hydrophobic molecules and nanoparticles from an organic solvent to an aqueous medium. The polymer helps to maintain a lipid-like microenvironment for the organic molecules to aid in preservation of their photochemical behavior in water. Thus this method is ideal to prepare water-dispersible photoresponsive systems. The use of near-infrared light to activate upconverting nanoparticles allows for lower energy light to be used to activate photoreactions instead of more harmful ultraviolet light.

Organic dye molecules and oleic acid coated upconverting nanoparticles are not water-soluble. This protocol describes a &#8216;plug and play&#8217; method that enables the transfer of organic dye molecules and upconverting particles from their initial hydrophobic solvent to water.

In this protocol, we first describe a procedure to synthesize lanthanide doped upconverting nanoparticles (UCNPs). We then demonstrate how to generate ...

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism.

A method for the atom transfer radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst is described.

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Engineering

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, allowing for the synthesis of isotactic poly(&#945;-hydroxy acids) with expected molecular weights (&#62;140 kDa) and narrow molecular weight distributions (Mw/Mn &#60; 1.1). This ring-opening polymerization is mediated by Ni and Zn complexes in the presence of an alcohol initiator and a photoredox Ir catalyst, irradiated by a blue LED (400 - 500 nm). The polymerization is performed at a low temperature (-15 &#176;C) to avoid undesired side reactions. The complete monomer consumption can be achieved within 4 - 8 hours, providing a polymer close to the expected molecular weight with narrow molecular weight distribution. The resulted number-average molecular weight shows a linear correlation with the degree of polymerization up to 1000. The homodecoupling 1H NMR study confirms that the obtained polymer is isotactic without epimerization. This polymerization reported herein offers a strategy for achieving rapid, controlled O-carboxyanhydrides polymerization to prepare stereoregular poly(&#945;-hydroxy acids) and its copolymers bearing various functional side-chain groups.

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

A protocol for the controlled photoredox ring-opening polymerization of O-carboxyanhydrides mediated by Ni/Zn complexes is presented.

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, ...

Fabrication of Spherical and Worm-shaped Micellar Nanocrystals by Combining Electrospray, Self-assembly, and Solvent-based Structure Control

Micellar nanocrystals (micelles with encapsulated nanocrystals) have become an emerging major class of nanobiomaterials. We describe a method of fabricating micellar nanocrystals based on combining top-down electrospray, bottom-up self-assembly, and solvent-based structure control. This method involves first using electrospray to generate uniform ultrafine liquid droplets, each of which functions as a micro-reactor in which self-assembly reaction occurs forming micellar nanocrystals, with the structures (micelle shape and nanocrystal encapsulation) controlled by the organic solvent used. This method is largely continuous and produces high quality micellar nanocrystal products with an inexpensive structure control approach. By using a water-miscible organic solvent tetrahydrofuran (THF), worm-shaped micellar nanocrystals can be produced due to solvent-induced/facilitated micelle fusion. Compared with the common spherical micellar nanocrystals, worm-shaped micellar nanocrystals can offer minimized non-specific cellular uptake, thus enhancing biological targeting. By co-encapsulating multiple nanocrystals into each micelle, multifunctional or synergistic effects can be achieved. Current limitations of this fabrication method, which will be part of the future work, primarily include imperfect encapsulation in the micellar nanocrystal product and the incompletely continuous nature of the process.

The present work describes a method to fabricate micellar nanocrystals, an emerging major class of nanobiomaterials. This method combines top-down electrospray, bottom-up self-assembly, and solvent-based structure control. The fabrication method is largely continuous, can produce high quality products, and possesses an inexpensive means of structure control.

Micellar nanocrystals (micelles with encapsulated nanocrystals) have become an emerging major class of nanobiomaterials. We describe a method of ...

Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) and fluorocarbon oil (perfluoro-n-octane, PFO) in aqueous surfactant (sodium dodecylsulfate, SDS) solutions. Since fluorocarbon oils are immiscible with hydrocarbon oils, the two oils are separated. Emulsions are prepared by stirring styrene/PFO/aqueous SDS solution mixtures at 80 &#176;C. The type of emulsions and the morphology of droplets in the emulsions are observed by light microscope and scanning confocal fluorescence microscope. It is found that oil droplets with Janus-type morphologies consisting of mutually immiscible styrene and PFO are formed in aqueous SDS solutions. Polystyrene particles are fabricated by radical polymerization of the ternary mixtures of styrene/PFO/aqueous SDS solution at 80 &#176;C. The morphologies of the polystyrene are confirmed by scanning electron microscopy and scanning transmission electron microscopy observations. These observations show the preparation of hollow polystyrene particles with a single hole on the surface. To our knowledge, this method is a novel strategy using the immiscibility of hydrocarbon and fluorocarbon oils. The hollow particles can also be applied to the preparation of microcapsules.

A protocol for the fabrication of hollow polymer particles and microcapsules by radical polymerization using emulsions consisting of styrene, perfluoro-n-octane, and aqueous SDS (sodium dodecylsulfate) solution is presented.

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) ...

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes and determine the corresponding photochemical mechanism. Then, we describe a protocol to perform ring-opening metathesis polymerization (ROMP) in solution and in miniemulsion using this NHC-photogenerating system. To photogenerate IMes, a system comprising 2-isopropylthioxanthone (ITX) as the sensitizer and 1,3-dimesitylimidazolium tetraphenylborate (IMesH+BPh4-) as the protected form of NHC is employed. IMesH+BPh4- can be obtained in a single step by anion exchange between 1,3-dimesitylimidazolium chloride and sodium tetraphenylborate. A real-time steady-state photolysis setup is described, which hints that the photochemical reaction proceeds in two consecutive steps: 1) ITX triplet is photo-reduced by the borate anion and 2) subsequent proton transfer takes place from the imidazolium cation to produce the expected NHC IMes. Two separate characterization protocols are implemented. Firstly, CS2 is added to the reaction media to evidence the photogeneration of NHC through formation of the IMes-CS2 adduct. Secondly, the amount of NHC released in situ is quantified using acid-base titration. The use of this NHC photo-generating system for the ROMP of norbornene is also discussed. In solution, a photopolymerization experiment is conducted by mixing ITX, IMesH+BPh4-, [RuCl2(p-cymene)]2 and norbornene in CH2Cl2, then irradiating the solution in a UV reactor. In a dispersed medium, a monomer miniemulsion is first formed then irradiated inside an annular reactor to produce a stable poly(norbornene) latex.

We describe a protocol to photogenerate N-heterocyclic carbenes (NHCs) by UV irradiation of a 2-isopropylthioxanthone/imidazolium tetraphenylborate salt system. Methods to characterize the photoreleased NHC and elucidate the photochemical mechanism are proposed. The protocols for ring-opening metathesis photopolymerization in solution and miniemulsion illustrate the potential of this 2-component NHC photogenerating system.

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes ...

Synthesis of Monodisperse Cylindrical Nanoparticles via Crystallization-driven Self-assembly of Biodegradable Block Copolymers

The production of monodisperse cylindrical micelles is a significant challenge in polymer chemistry. Most cylindrical constructs formed from diblock copolymers are produced by one of three techniques: thin film rehydration, solvent switching or polymerization-induced self-assembly, and produce only flexible, polydisperse cylinders. Crystallization-driven self-assembly (CDSA) is a method which can produce cylinders with these properties, by stabilizing structures of a lower curvature due to the formation of a crystalline core. However, the living polymerization techniques by which most core-forming blocks are formed are not trivial processes and the CDSA process may yield unsatisfactory results if carried out incorrectly. Here, the synthesis of cylindrical nanoparticles from simple reagents is shown. The drying and purification of reagents prior to a ring-opening polymerization of &#949;-caprolactone catalyzed by diphenyl phosphate is described. This polymer is then chain extended by methyl methacrylate (MMA) followed by N,N-dimethyl acrylamide (DMA) using reversible addition&#8722;fragmentation chain-transfer (RAFT) polymerization, affording a triblock copolymer that can undergo CDSA in ethanol. The living CDSA process is outlined, the results of which yield cylindrical nanoparticles up to 500 nm in length and a length dispersity as low as 1.05. It is anticipated that these protocols will allow others to produce cylindrical nanostructures and elevate the field of CDSA in the future.

Crystallization-driven self-assembly (CDSA) displays the unique ability to fabricate cylindrical nanostructures of narrow length distributions. The organocatalyzed ring-opening polymerization of &#949;-caprolactone and subsequent chain extensions of methyl methacrylate and N,N-dimethyl acrylamide are demonstrated. A living CDSA protocol that produces monodisperse cylinders up to 500 nm in length is outlined.

The production of monodisperse cylindrical micelles is a significant challenge in polymer chemistry. Most cylindrical constructs formed from diblock ...

Self-Assembly of Polymer-Grafted Metal Organic Framework Monolayers

Synthesis and Characterization of Self-Assembled Metal-Organic Framework Monolayers Using Polymer-Coated Particles

Metal-organic frameworks (MOFs) are materials with potential applications in fields such as gas adsorption and separation, catalysis, and biomedicine. Attempts to enhance the utility of MOFs have involved the preparation of various composites, including polymer-grafted MOFs. By directly grafting polymers to the external surface of MOFs, issues of incompatibility between polymers and MOFs can be overcome. Polymer brushes grafted from the surface of MOFs can serve to stabilize the MOF while enabling particle assembly into self-assembled metal-organic framework monolayers (SAMMs) via polymer-polymer interactions.
Control over the chemical composition and molecular weight of the grafted polymer can allow for tuning of the SAMM characteristics. In this work, instructions are provided on how to immobilize a chain transfer agent (CTA) onto the surface of the MOF UiO-66 (UiO = Universitetet i Oslo). The CTA&#160;serves as initiation sites for the growth of polymers. Once polymer chains are grown from the MOF surface, the formation of SAMMs is achieved through self-assembly at an air-water interface. The resulting SAMMs are characterized and shown to be freestanding by scanning electron microscopy imaging. The methods presented in this paper are expected to make the preparation of SAMMs more accessible to the research community and thereby expand their potential use as a&#160;MOF-polymer composite.

Author Spotlight: Exploring Self-Assembled MOF-Polymer Composites

A protocol for the synthesis and characterization of self-assembled metal-organic framework monolayers is provided using polymer-grafted, metal-organic framework (MOF) crystals. The procedure shows that polymer-grafted MOF particles can be self-assembled at an air-water interface resulting in well-formed, free-standing, monolayer structures as evidenced by scanning electron microscopy imaging.

Metal-organic frameworks (MOFs) are materials with potential applications in fields such as gas adsorption and separation, catalysis, and biomedicine. ...

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

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