Name: layer-by-layer synthesis and transfer of freestanding conjugated microporous polymer nanomembranes
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The authors have no acknowledgements.

1. Sintesi di CMP film sottili attraverso l&#39;aggiunta sequenziale <ol><li> Auto-assemblati monostrato (SAM) funzionalizzazione di oro su mica. <ol><li> Preparare la soluzione 1 mM di 11-thioacetyl-undecano acid-propargyl ammide 14 in etanolo (SAM-soluzione). Miscelare con bagno a ultrasuoni fino a soluzione è limpida. Proteggere la bottiglia dalla luce utilizzando un foglio di alluminio. </li><li> Ottenere l&#39;oro rivestite mica wafer sotto argon. Dopo il ritiro dal contenitore immergere il wafer mica direttamente alla SAM-soluzione per 18 ore. </li><li> Prendere il preparato Au-mica cialda fuori dalla SAM-soluzione, risciacquare con etanolo e secco sotto corrente di azoto. Successivamente memorizzare il substrato al riparo dalla luce e sotto gas inerte. </li></ol></li><li> Soluzioni Precursore. <ol><li> Pesare 18.64 mg di Cu-catalizzatore (Tetrakis (acetonitrile) rame (I) esafluoro-fosfato), 20,83 mg tetrafenilmetano (TPM) -alkyne e 24.22 mg TPM-azide e riempire ogni componente in un pallone Schlenk separata.Vedere la Figura 1 per TPM-alchino e TPM-azide, la sintesi è descritto in riferimento 15. Evacuare e riempire con gas inerte (N 2 o argon) 3 volte. </li><li> Aggiungere 25 ml di tetraidrofurano privo di acqua (THF) ad ogni pallone Schlenk. Proteggere i palloni con TPM-azide e TPM-alkyne dalla luce con un foglio di alluminio. </li></ol></li><li> Preparare apparecchi per la fabbricazione CMP. Nota: L&#39;apparato di sintesi è illustrato nella figura 2. <ol><li> Utilizzare un pallone a fondo tondo da 250 ml un collo. Compilare 130 ml THF. Mettere il substrato preparata rivestito con alkyne terminato SAM nel vano campione. Utilizzare un portacampioni, in modo che il substrato è in piedi. </li><li> Collegare l&#39;apparecchiatura alla linea schlenk tramite giunzione sopra il refrigerante a ricadere. </li><li> Evacuare e ventilare con gas inerte per 3 volte. </li></ol></li><li> Inoltre sequenziale in condizioni inerti. <ol><li> Impostare il riscaldamento a 90 ° C e aspettare che il THF è reflussaggio. </li><li> Lasciare fuori THF dal vano del campione sopra la presa sul fondo del vano campione. Chiudere la presa. </li><li> Dare 1 ml della soluzione TPM-azide preparati e 0,5 ml della soluzione di Cu (I) catalizzatore per il compartimento del campione attraverso il tappo a vite con setto. Utilizzare una siringa con un ago cavo per trasferire la soluzione in sequenza dal pallone Schlenk all&#39;apparecchio reazione. Nota: La sequenza non ha alcuna influenza alla reazione. </li><li> Attendere circa 30 minuti. </li><li> Lasciare la soluzione di reazione sopra la presa sul fondo del vano campione. Chiudere l&#39;uscita e raccogliere il THF condensata per il risciacquo del campione. Attendere circa 30 minuti. </li><li> Lasciare la soluzione di risciacquo sopra la presa sul fondo del vano campione. Chiudere la presa. </li><li> Dare 1 ml della soluzione TPM-alchino preparati e 0,5 ml della soluzione di Cu (I) catalizzatore per il compartimento del campione attraverso il tappo a vite con setto. Utilizzare una siringa con una cavitàago per trasferire la soluzione in sequenza dal pallone Schlenk all&#39;apparecchio reazione. Nota: La sequenza non ha alcuna influenza alla reazione. </li><li> Attendere circa 30 minuti. </li><li> Lasciare la soluzione di reazione sopra la presa sul fondo del vano campione. Chiudere l&#39;uscita e raccogliere il THF condensata per il risciacquo del campione. Attendere circa 30 minuti. </li><li> Ripetere i passaggi da 1.4.3 a 1.4.9 fino al raggiungimento della quantità desiderata di strati. Nota: Un uno spessore di circa 1 nm. </li><li> Estrarre il substrato di mica rivestite CMP, sciacquarlo con THF, etanolo e asciugare in corrente di azoto. </li></ol></li></ol> 2. Trasferimento di CMP nanomembrane <ol><li> Soluzione di poli (metilmetacrilato) (PMMA). <ol><li> Preparare una soluzione di 4% (in peso) PMMA (M 996 kDa) in acetato di etile. Sciogliere il PMMA utilizza bagno a ultrasuoni fino alla soluzione è limpida. </li></ol></li><li> Spin coating di soluzione PMMA. <ol><li> Impostare il dispositivo a induzione di rotazione a Ratempo mp 10 secondi da 0 a 4.000 giri, tempo di mantenimento 40 sec e il tempo di rampa 10 secondi da 4.000 a 0 rpm. </li><li> Posizionare il CMP substrato di mica rivestito sulla coater rotazione e mettere la soluzione PMMA sul wafer finchè è completamente coperto. Avviare il dispositivo a induzione di rotazione. </li><li> Dopo spin coating è completato, mettere il campione per 5 minuti su una piastra riscaldante a 90 ° C. </li><li> Tagliare 1 mm da ogni bordo del substrato mica rivestita. Utilizzare una forbice per tagliare i bordi. </li></ol></li><li> Trasferimento di PMMA rivestito CMP nanomembrana. <ol><li> Preparare la soluzione di I 2 / KI / H 2 O (1: 4: 40 m / m / m) e KI / H 2 O (1:10 m / m). </li><li> Riempire la soluzione che ho 2 / KI H 2 O in 150 ml cristallizzazione piatto e riempire la soluzione KI / H 2 O in 100 ml di cristallizzazione piatto. Mettere l&#39;oro CMP PMMA rivestiti su substrato di mica, mica in contatto soluzione, in cima alla I 2 / KI / H 2 O soluzione. Fate attenzione che non affonda.Attendere almeno 5 minuti. </li><li> Mettere il CMP oro substrato di mica rivestite PMMA dalla I 2 / KI / H 2 O soluzione sopra della soluzione KI / H 2 O, con mica in contatto soluzione. Fate attenzione che non affonda. Attendere almeno 5 minuti. </li><li> Riempire acqua distillata in 250 ml cristallizzazione piatto. Togliere il / pellicola / oro CMP PMMA dal mica. A tale scopo, leggermente immergendo il substrato, a partire da un bordo, in acqua distillata. Tenere il substrato in modo che la mica punta all&#39;acqua. Nota: La procedura è illustrata nella figura 3. </li><li> Dip-coat PMMA / CMP / oro sul wafer di silicio. A tale scopo, si avvicina il PMMA / CMP / oro lentamente con la cialda fino a toccare bordo della piscina PMMA / membrana / oro CMP. Estrarre il wafer di silicio lentamente, una volta che il Si-wafer è in contatto con il / CMP membrana PMMA / oro. </li><li> Striscia la / CMP pellicola PMMA / oro fuori dal wafer di silicio. A tale scopo, un po &#39;immergendo il substrato, a cominciare da una cura dige, in I 2 / KI / H 2 O soluzione. Aspettare 15 minuti. </li><li> Dopo l&#39;oro è completamente inciso, trasferire la membrana PMMA / CMP di acqua attraverso il wafer di silicio. Aspettare 15 minuti. </li><li> Ripetere il punto 2.3.7 tre volte per lavare la membrana con acqua. </li><li> Trasferire la membrana PMMA / CMP lavato al substrato desiderato, ad esempio, un vetrino o un oro rivestite wafer di silicio, tramite il metodo indicato nel passaggio 2.3.5. Lasciate che il PMMA / CMP supporto asciutto in aria per almeno 2 ore. </li></ol></li><li> Scioglimento del PMMA. <ol><li> Mettere il substrato PMMA / CMP in acetone. Attendere 30 min. Estrarre il substrato e risciacquare con acetone. </li><li> Ripetere il punto 2.4.1 tre volte. </li><li> Lasciate che il CMP supporto asciutto per almeno 2 ore. </li></ol></li></ol>

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The authors have nothing to disclose.

Per la sintesi del CMP film la soluzione del catalizzatore deve essere fresco. Un catalizzatore rotto (cioè, ossidato) è indicato da una colorazione blu della soluzione. La soluzione fresca è incolore. Un punto cruciale è per tagliare i bordi del substrato di mica dopo spin coating PMMA. Anche difetti del substrato deve essere tagliato, cioè, ogni punto fosse il PMMA può venire in contatto con il substrato di mica, a causa di uno strato di oro mancante. Altrimenti lo strato di oro non può essere tolto dal substrato di mica facilmente. Anche per quanto riguarda il distacco dello strato di oro dal substrato di mica, dopo il distacco iniziato su un bordo o angolo, si dovrebbe continuare su questo bordo fino alla strato di oro è completamente staccato. Durante il trasferimento delle membrane PMMA / CMP con un wafer di silicio, ad esempio, dal bagno di acqua alla soluzione di iodio o dalla soluzione di iodio all&#39;acqua, è importante chela membrana non asciuga. Una volta che la membrana si asciuga sul Si-wafer, è quasi impossibile staccherà nuovamente. Dopo aver dissolto il PMMA, ogni fase di risciacquo deve essere eseguita con cautela; un bordo sovrapposto dalla membrana può portare ad una rimozione della membrana dal substrato. Al momento la dimensione dei campioni è limitata dalla dimensione del vano campione. Lo spessore dei film CMP fabbricati è limitata dal tempo di reazione, perché ogni ciclo ha bisogno di circa 2 ore. Per una sintesi meno laborioso dell&#39;apparato reazione potrebbe essere modificato aggiungendo un sifone; di conseguenza il compartimento campione sarà svuotato automaticamente, paragonabile ad un estrattore Soxhlet. La nostra tecnica combina trattamento dei coniugati film polimerici microporosi ultrasottili e l&#39;uso di un substrato sacrificale per ottenere nanomembrane CMP. La sintesi di nanomembrane CMP ancora non è stato possibile a causa delbassa lavorabilità di polvere CMP. In confronto ad altre tecniche, per esempio la produzione di SURMOFs 7, abbiamo ottenuto una riduzione della quantità di solvente utilizzato. Soprattutto la fase di risciacquo in caso di produzione SURMOF ha un elevato consumo di solvente, in questo caso, a causa dell&#39;uso di riflusso THF, si potrebbe diminuire il consumo di THF drasticamente. Ci aspettiamo che il metodo presentato troverà applicazione in gas e separazione di fase liquido a causa della possibilità di ottimizzare la selettività e permeance dal controllo sulla dimensione dei pori e affinità chimica. Inoltre, la sintesi modulare di materiali CMP da blocchi funzionali adatti per altre applicazioni, quali la catalisi, rilevamento, o elettronica organica, potrebbe beneficiare del metodo di lavorazione descritto.

The preparation of ultra-thin polymer membranes is of high interest for applications in gas separation and nanofiltration. Challenges in the synthesis are represented by (a) the control of the membrane thickness and the homogeneity and (b) transfer of such fragile membranes. To overcome challenge (a), molecular layer-by-layer synthesis1 has shown great promise in controlling the thickness and homogeneity of thin films grown at the solid-liquid interface.2,3 Controlling the number of layers linearly controls the film thickness. The l-b-l method has been successfully used to fabricate surface mounted metal organic frameworks (SURMOFs),4-7 also the synthesis of thin polymer films via l-b-l reaction of polymer chains was demonstrated.8 The challenge (b) concerns the handling of these ultra-thin membranes. To avoid rupture or wrinkling of the nanomembranes sacrificial supports of coatings have shown great promise. 9
Here we will present a detailed protocol for synthesis of conjugated microporous polymer (CMP)10-13 thin films through sequential addition of the molecular building blocks, with desired thickness and composition. The preparation of free-standing CMP nanomembranes is achieved by using a sacrificial support. To handle and transfer the CMP nanomembranes to other supports we will describe a simple protocol to protect the membranes with sacrificial coatings and their upfloating to the liquid air interface and subsequent transfer using dip-coating.

<table><tbody><tr><td>Acetone</td><td>VWR BDH Prolabo</td><td>20066.330</td><td>AnalR NORMAPUR</td></tr><tr><td>Potassium iodide</td><td>VWR BDH Prolabo</td><td>26846.292</td><td>AnalR NORMAPUR</td></tr><tr><td>Ethyl acetate</td><td>VWR BDH Prolabo</td><td>23882.321</td><td>AnalR NORMAPUR</td></tr><tr><td>Tetrahydrofuran (THF)</td><td>VWR BDH Prolabo</td><td>28559.320</td><td>HiPerSolv CHROMANORM</td></tr><tr><td>THF waterfree</td><td>Merck Millipore</td><td>1.08107.1001</td><td>SeccoSolv</td></tr><tr><td>Iodine</td><td>Sigma-Aldrich</td><td>20,777-2</td><td></td></tr><tr><td>Tetrakis(acetonitrile) copper(I) hexafluoro-phosphate</td><td>Sigma-Aldrich</td><td>346276-5G</td><td></td></tr><tr><td>Poly(methyl methacrylate) 996 kDa (PMMA)</td><td>Sigma-Aldrich</td><td>182265-25G</td><td></td></tr><tr><td>1.1.1.1 Methanetetrayltetrakis(4-azidobenzene) (TPM-azide)</td><td></td><td></td><td>Provided by AK Prof. Br&amp;auml;se. Institute of organic chemistry, Karlsruhe Institute of Technology. Synthesized according to &lt;sup&gt;9&lt;/sup&gt;.</td></tr><tr><td>1.1.1.1 Methanetetrayltetrakis(4-ethinylenebenzene) (TPM-alkyne)</td><td></td><td></td><td>Provided by AK Prof. Br&amp;auml;se. Institute of organic chemistry, Karlsruhe Institute of Technology. Synthesized according to &lt;sup&gt;9&lt;/sup&gt;.</td></tr><tr><td>11-thioacetyl-undecaneacid propargylamide</td><td></td><td></td><td>Provided by AK Prof. Br&amp;auml;se. Institute of organic chemistry, Karlsruhe Institute of Technology. Synthesized according to &lt;sup&gt;8&lt;/sup&gt;.</td></tr><tr><td>gold/titan coated silicium-wafer</td><td>Georg Albert PVD, 76857 Silz, Germany</td><td></td><td></td></tr><tr><td>gold coated mica</td><td>Georg Albert PVD, 76857 Silz, Germany</td><td></td><td></td></tr></tbody></table>

layer-by-layer synthesis and transfer of freestanding conjugated microporous polymer nanomembranes

CMP come grandi materiali Superficie hanno suscitato crescente interesse recente, a causa della loro elevata variabilità nella incorporazione di gruppi funzionali in combinazione con loro eccezionale stabilità termica e chimica e basse densità. Tuttavia, la loro natura insolubile causa problemi nella loro lavorazione poiché le tecniche normalmente applicate come rivestimento a rotazione non sono disponibili. Specialmente per le applicazioni di membrana, in cui il trattamento di CMP come film sottili è desiderabile, i problemi di elaborazione hanno ostacolato la loro applicazione commerciale. Qui si descrive la sintesi interfacciale di film sottili su substrati funzionalizzati CMP tramite layer-by-layer (LBL) sintesi molecolare. Questo processo consente di ottenere film con spessore desiderato e composizione e gradienti di composizione persino desiderati. L&#39;uso di supporti sacrificali permette la preparazione di membrane autoportanti mediante dissoluzione del supporto dopola sintesi. Per gestire tali membrane autoportanti ultrasottili di protezione con rivestimenti sacrificali ha mostrato grande promessa, per evitare la rottura delle nanomembrane. Per trasferire i nanomembrane al substrato desiderato, le membrane sono rivestite upfloated all&#39;interfaccia aria-liquido e quindi trasferiti tramite dip coating.

Le membrane sono caratterizzati mediante spettroscopia di assorbimento infrarosso riflessione (IRRAS). 16 Figura 4 mostra IRRA-spettri da un CMP-membrana trasferito ad un wafer oro. Bande tipiche vibrazioni della dorsale aromatico sono a 1,605 cm -1, 1.515 cm -1 e 1.412 cm -1. Reagiti gruppi alchini e azide può essere osservato da bande caratteristici a 2.125 cm -1 e 1.227 cm -1. La Figura 5 mostra una immagine al microscopio elettronico a scansione (SEM). La membrana autoportante è chiaramente visibile. <img alt="Figura 1" src="/files/ftp_upload/53324/53324fig1highres.jpg" width="550" /> Figura 1. mattoni molecolari. Strutture molecolari di (A) TPM-alkyne e (B) TPM-azide. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53324/53324fig1large.jpg" target="_blank">Pl</a>facilità clicca qui per vedere una versione più grande di questa figura. <img alt="Figura 2" src="/files/ftp_upload/53324/53324fig2highres.jpg" width="700" /> Figura 2. apparato di reazione. Impostare per la sintesi layer-by-layer dei CMP film sottili. L&#39;apparecchiatura consiste in un pallone a fondo tondo collo come un serbatoio per l&#39;THF, il tubo vapore per portare il vapore THF al refrigerante a ricadere. I condensati THF sono raccolti nel compartimento campione. I prodotti chimici possono essere inseriti sul tappo a vite con un setto. Il vano campione viene svuotato attraverso l&#39;uscita in basso. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53324/53324fig2large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 3" src="/files/ftp_upload/53324/53324fig3highres.jpg" width="500" /> Figura 3. Rimozione mica. </strong&gt; La membrana PMMA / CMP sta cominciando a staccarsi dal bordo del substrato di mica. Metà del PMMA / CMP galleggia sopra l&#39;acqua, l&#39;altra metà è ancora attaccato al substrato di mica. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53324/53324fig3large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 4" src="/files/ftp_upload/53324/53324fig4highres.jpg" width="700" /> Figura 4. IRRA-spettri. IRRA-spettri da un CMP-membrana trasferito ad un oro-wafer. Le bande dalle vibrazioni della spina dorsale aromatico a 1.605, 1.515 e 1.412 cm -1 sono caratteristici per il CMP-membrana. La vibrazione del CD è dovuto alla sfondo utilizzato. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53324/53324fig4large.jpg" target="_blank">Cliccate qui per vedere una versione più grande di questa figura.</a> Figura 5. SEM-immagine. SEM-Immagine della CMP-membrana. La membrana freestanding è ben indicata. (Ristampato con il permesso di Lindemann, P et al Chem Mater 26, 7189 -.... 7193. Copyright 2014 American Chemical Society.) <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53324/53324fig5large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a>

Watch this Scientific Journal Video about Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes at JoVE.com

Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes

In this paper we describe the interfacial synthesis of conjugated microporous polymers (CMP) on sacrificial substrates, and the dissolution of the substrate for the preparation of freestanding CMP nanomembranes. In addition, we will describe how the fragile nanomembranes can be transferred to other substrates.

Sintesi layer-by-layer e di trasferimento delle Freestanding coniugati microporosi Polymer nanomembrane

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in ...

layer-layer-synthesis-transfer-freestanding-conjugated-microporous

Nanyang Technological University

Research

JoVE Journal

Chemistry

9.3K Views.  Karlsruhe Institute of Technology. In this paper we describe the interfacial synthesis of conjugated microporous polymers (CMP) on sacrificial substrates, and the dissolution of the substrate for the preparation of freestanding CMP nanomembranes. In addition, we will describe how the fragile nanomembranes can be transferred to other substrates.

Video: Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes

Fabrication of Large-area Free-standing Ultrathin Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.

We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.

Fabbricazione di ampia superficie Free-standing ultrasottili film polimerici

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films.  Typically, ultrathin films are prepared ...

Ricerca

Chimica

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

Preparazione di altamente poroso Coordinamento rivestimenti polimerici su macroporosi Polymer Monoliti di avanzata Arricchimento fosfopeptidi

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Fabrication of the Thermoplastic Microfluidic Channels

In our lab, we have successfully isolated nucleic acids directly from microliter and submicroliter volumes of human blood, urine and stool using polymer/nanoparticle composite microscale lysis and solid phase extraction columns. The recovered samples are concentrated, small volume samples that are PCRable, without any additional cleanup. Here, we demonstrate how to fabricate thermoplastic microfluidic chips using hot embossing and heat sealing. Then, we demonstrate how to use in situ light directed surface grafting and polymerization through the sealed chip to form the composite solid phase columns. We demonstrate grafting and polymerization of a carbon nanotube/polymer composite column for bacterial cell lysis. We then show the lysis process followed by solid phase extraction of nucleic acids from the sample on chip using a silica/polymer composite column. The attached protocols contain detailed instructions on how to make both lysis and solid phase extraction columns.

Here we demonstrate how to fabricate thermoplastic microfluidic chips using hot embossing and heat sealing. Then we demonstrate how to use in situ light directed surface grafting and polymerization through the sealed chip to form the composite solid phase columns.

Fabbricazione dei canali termoplastico Microfluidic

In our lab, we have successfully isolated nucleic acids directly from microliter and submicroliter volumes of human blood, urine and stool using ...

Biologia

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.

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.

Sintesi facile di micelle vermiforme dalla luce visibile mediata polimerizzazione in dispersione Utilizzando Photoredox Catalyst

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

Creating Sub-50 Nm Nanofluidic Junctions in PDMS Microfluidic Chip via Self-Assembly Process of Colloidal Particles

Polydimethylsiloxane (PDMS) is the prevailing building material to make microfluidic devices due to its ease of molding and bonding as well as its transparency. Due to the softness of the PDMS material, however, it is challenging to use PDMS for building nanochannels. The channels tend to collapse easily during plasma bonding. In this paper, we present an evaporation-driven self-assembly method of silica colloidal nanoparticles to create nanofluidic junctions with sub-50 nm pores between two microchannels. The pore size as well as the surface charge of the nanofluidic junction is tunable simply by changing the colloidal silica bead size and surface functionalization outside of the assembled microfluidic device in a vial before the self-assembly process. Using the self-assembly of nanoparticles with a bead size of 300 nm, 500 nm, and 900 nm, it was possible to fabricate a porous membrane with a pore size of ~45 nm, ~75 nm and ~135 nm, respectively. Under electrical potential, this nanoporous membrane initiated ion concentration polarization (ICP) acting as a cation-selective membrane to concentrate DNA by ~1,700 times within 15 min. This non-lithographic nanofabrication process opens up a new opportunity to build a tunable nanofluidic junction for the study of nanoscale transport processes of ions and molecules inside a PDMS microfluidic chip.

We propose a simple self-assembly technique of silica colloidal nanoparticles to create a nanofluidic junction between two microchannels in polydimethylsiloxane (PDMS). Using this technique, a nanoporous bead membrane with a pore size down to ~45 nm was built inside a microchannel and applied to electrokinetic preconcentration of DNA samples.

Creazione di Sub-50 Nm nanofluidic giunzioni in PDMS Microfluidic Chip tramite processo di auto-assemblaggio di particelle colloidale

Polydimethylsiloxane (PDMS) is the prevailing building material to make microfluidic devices due to its ease of molding and bonding as well as its ...

Ingegneria

Preparation of Light-responsive Membranes by a Combined Surface Grafting and Postmodification Process

In order to modify the surface tension of commercial available track-edged polymer membranes, a procedure of surface-initiated polymerization is presented. The polymerization from the membrane surface is induced by plasma treatment of the membrane, followed by reacting the membrane surface with a methanolic solution of 2-hydroxyethyl methacrylate (HEMA). Special attention is given to the process parameters for the plasma treatment prior to the polymerization on the surface. For example, the influence of the plasma-treatment on different types of membranes (e.g.&#160;polyester, polycarbonate, polyvinylidene fluoride) is studied. Furthermore, the time-dependent stability of the surface-grafted membranes is shown by contact angle measurements. When grafting poly(2-hydroxyethyl methacrylate) (PHEMA) in this way, the surface can be further modified by esterification of the alcohol moiety of the polymer with a carboxylic acid function of the desired substance. These reactions can therefore be used for the functionalization of the membrane surface. For example, the surface tension of the membrane can be changed or a desired functionality as the presented light-responsiveness can be inserted. This is demonstrated by reacting PHEMA with a carboxylic acid functionalized spirobenzopyran unit which leads to a light-responsive membrane. The choice of solvent plays a major role in the postmodification step and is discussed in more detail in this paper. The permeability measurements of such functionalized membranes are performed using a Franz cell with an external light source. By changing the wavelength of the light from the visible to the UV-range, a change of permeability of aqueous caffeine solutions is observed.

A plasma-induced polymerization procedure is described for the surface-initiated polymerization on polymer membranes. Further postmodification of the grafted polymer with photochromic substances is presented with a protocol of conducting permeability measurements of light-responsive membranes.

Preparazione di membrane Light-responsive da un innesto superficie combinata e Postmodifica processo

In order to modify the surface tension of commercial available track-edged polymer membranes, a procedure of surface-initiated polymerization is ...

Bioingegneria

Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and non-porous supports (polymer, ceramic, metal, carbon, and graphene). We developed a novel crystallization technique, which is termed the ENACT approach: the electrophoretic nuclei assembly for the crystallization of highly intergrown thin films (ENACT). This approach allows for a high density of heterogeneous nucleation of MOFs on a chosen substrate via the electrophoretic deposition (EPD) directly from the precursor sol. The growth of well-packed MOF nuclei leads to a highly intergrown polycrystalline MOF film. We show that this simple approach can be used for the synthesis of thin, intergrown zeolite imidazole framework (ZIF)-7 and ZIF-8 films. The resulting 500 nm-thick ZIF-8 membranes show a considerably high H2 permeance (8.3 x 10-6 mol m-2 s-1 Pa-1) and ideal gas selectivities (7.3 for H2/CO2, 15.5 for H2/N2, 16.2 for H2/CH4, and 2655 for H2/C3H8). An attractive performance for C3H6/C3H8 separation is also achieved (a C3H6 permeance of 9.9 x 10-8 mol m-2 s-1 Pa-1 and a C3H6/C3H8 ideal selectivity of 31.6 at 25 &#176;C). Overall, the ENACT process, owing to its simplicity, can be extended to synthesize intergrown thin films of a wide range of nanoporous crystalline materials.

A simple, reproducible, and versatile approach for the synthesis of intergrown, polycrystalline metal-organic framework membranes on a wide range of unmodified porous and non-porous supports is presented.

Elettroforetica cristallizzazione delle membrane ultrasottile ad alte prestazioni Metal-organic frameworks

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and ...

Procedure for the Transfer of Polymer Films Onto Porous Substrates with Minimized Defects

The fabrication of devices containing thin film composite membranes necessitates the transfer of these films onto the surfaces of arbitrary support substrates. Accomplishing this transfer in a highly controlled, mechanized, and reproducible manner can eliminate the creation of macroscale defect structures (e.g., tears, cracks, and wrinkles) within the thin film that compromise device performance and the usable area per sample. Here, we describe a general protocol for the highly controlled and mechanized transfer of a polymeric thin film onto an arbitrary porous support substrate for eventual use as a water filtration membrane device. Specifically, we fabricate a block copolymer (BCP) thin film on top of a sacrificial, water-soluble poly(acrylic acid) (PAA) layer and silicon wafer substrate. We then utilize a custom-designed, 3D-printed transfer tool and drain chamber system to deposit, lift-off, and transfer the BCP thin film onto the center of a porous anodized aluminum oxide (AAO) support disc. The transferred BCP thin film is shown to be consistently placed onto the center of the support surface due to the guidance of the meniscus formed between the water and the 3D-printed plastic drain chamber. We also compare our mechanized transfer-processed thin films to those that have been transferred by hand with the use of tweezers. Optical inspection and image analysis of the transferred thin films from the mechanized process confirm that little-to-no macroscale inhomogeneities or plastic deformations are produced, as compared to the multitude of tears and wrinkles produced from manual transfer by hand. Our results suggest that the proposed strategy for thin film transfer can reduce defects when compared to other methods across many systems and applications.

We present a procedure for highly controlled and wrinkle-free transfer of block copolymer thin films onto porous support substrates using a 3D-printed drain chamber. The drain chamber design is of general relevance to all procedures involving transfer of macromolecular films onto porous substrates, which is normally done by hand in an irreproducible fashion.

Procedura per il trasferimento di pellicole polimeriche su substrati porous con difetti ridotti al minimo

The fabrication of devices containing thin film composite membranes necessitates the transfer of these films onto the surfaces of arbitrary support ...

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and thus achieving stable water permeability through membranes over time. Here, we report a facile method to prepare hydrogels based on zwitterions for membrane applications. Freestanding films can be prepared from sulfobetaine methacrylate (SBMA) with a crosslinker of poly(ethylene glycol) diacrylate (PEGDA) via photopolymerization. The hydrogels can also be prepared by impregnation into hydrophobic porous supports to enhance the mechanical strength. These films can be characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine the degree of conversion of the (meth)acrylate groups, using goniometers for hydrophilicity and differential scanning calorimetry (DSC) for polymer chain dynamics. We also report protocols to determine the water permeability in dead-end filtration systems and the effect of foulants (bovine serum albumin, BSA) on membrane performance.

This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.

Sintesi di idrogel con proprietà antivegetative come membrane per la purificazione dell&#39;acqua

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and ...

Autoassemblaggio di monostrati di struttura organica metallica innestata con polimero

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.

Autore in primo piano: Esplorazione dei compositi MOF-polimero autoassemblati

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.

Sintesi e caratterizzazione di monostrati di strutture metallo-organiche autoassemblate utilizzando particelle rivestite di polimero

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