Post-polymerization Reactions Research Articles

Modifications of Hydroxyl-Functionalized HEA/HEMA and Their Polymers in the Synthesis of Functional and Graft Copolymers

Background: Functional groups have played a fundamental role in synthesis of polymers due to they decide about polymerization methods, and influence on their topologies, properties and applications. The functional polymers are used as a high-performance materials with well-adjusted properties by modification of functionalities that can be addressed selectively to a variety of applications, usually in biomedical field. Objective: In this minireview article hydroxy-functionalized polymers, mostly based on 2-hydroxyethyl methacrylate (HEMA) or 2-hydroxyethyl acrylate (HEA), are discussed as products of the controlled polymerizations and as substrates in the functionalization reactions. Conclusion: The hydroxyl group gives opportunity for prepolymerization reactions, including protection group and macromonomer preparation. Multifunctional (co)polymers of HEMA/HEA contain reactive hydroxyl groups, which are directly accessible or caring suitable protective groups that can be removed or/and modified by post-polymerization reactions. The variation of approaches let to obtain functional polymers with linear, star-shape and graft topologies as the well-defined structures for the advanced functional materials, including smart polymeric devices.

Synthesis and Ozone Degradation of Alternating Copolymers ofN‐Substituted Maleimides with Diene Monomers

Radical copolymerization ofN‐substituted maleimides (RMIs) and maleic anhydride (MAn) in combination with 2,4‐dimethyl‐1,3‐pentadiene (DMPD) and 1,3‐pentadiene (PD) provides alternating copolymers with excellent thermal stability. Onset temperatures of decomposition are 280–331 and 336–371 °C for the copolymers with DMPD and PD, respectively. Glass transition temperatures of RMI copolymers are in a wide range of 54–138 °C depending on the bulkiness ofN‐substituents. MAn copolymers are transformed to the corresponding RMI copolymers by postpolymerization reactions, which consist of quantitative addition of an alkylamine to an anhydride moiety of MAn copolymers and the subsequent heating. The copolymers synthesized in this study include ozone‐degradable carbon‐to‐carbon double bonds in their main chain. Molecular weight of the copolymers rapidly decreases by ozone degradation. Surface modification of casted polymer films is also performed by exposure to ozone‐containing air.

Rigid-to-Flexible Conformational Transformation: An Efficient Route to Ring-Opening of a Tröger's Base-Containing Ladder Polymer.

The synthesis of ladder polymers is still a big challenge in polymer chemistry, and in particular, there are few examples of conformationally flexible well-defined ladder polymers. Here we report an efficient and convenient route to conformationally flexible ladder polymers, which is based on a postpolymerization reaction of a rigid ladder polymer containing Tröger's base in its main chain. The postpolymerization reaction involves sequential N-methylation and hydrolysis for the Tröger's base unit, resulting in a diazacyclooctane skeleton that can exhibit a ring-flipping motion. Molecular dynamics simulations predicted that this motion provides conformational flexibility with the resultant ladder polymer, which was demonstrated by 1H NMR spectroscopy in solution. The presence of the diazacyclooctane units in the flexible ladder polymer allowed further functionalization through reactions involving its secondary amine moiety. The present synthetic method may lead to the development of a new class of ladder polymers that exhibit both conformational and design flexibility.

Formation of Tough Films by Evaporation of Water from Dispersions of Elastomer Microspheres Crosslinked with Rotaxane Supramolecules.

Compared to rigid microspheres that consist, for example, of polystyrene or silica, soft and deformable elastomer microspheres can be used to generate colorless transparent films upon evaporating the solvent from microsphere-containing dispersions. To obtain tough films, a post-polymerization reaction to crosslink the microspheres is usually necessary, which requires extra additives during the drying process. This restriction renders this film-formation technology complex and rather unsuitable for applications in which impurities are undesirable. In the present study, it is demonstrated that tough elastomer microspheres that are crosslinked with rotaxanes can form tough bulk films upon evaporation of water from microsphere dispersions, so that post-polymerization reactions are not required. The results of this study should thus lead to new applications including coatings for biomaterials that need complete removal of all impurities from the materials prior to use.

Microspheres of polyurethanes functionalized with push-pull type azo chromophores and their photoinduced deformation behavior

A series of azo polyurethanes bearing push-pull type azo chromophores was synthesized by post-polymerization azo-coupling reactions between a polyurethane precursor and diazonium salts of different aniline derivatives, respectively. Colloidal spheres with narrow size distributions were obtained by aggregation of these azo polyurethanes in DMF-H2O mixed solvents, which were induced by slowly increasing the water content. The self-assembling processes and formed structures were investigated by laser light scattering and transmission electron microscopy. When irradiated with linearly polarized light from Ar+ laser (488 nm) and diode solid state laser (532 nm), the azo polyurethane microspheres showed significant deformations elongated in the light polarization direction. The electron-withdrawing groups on the azo chromophores show a significant effect on the photoinduced deformation degree. These microspheres composed of the azo polyurethanes bearing carboxylic acid and trifluoromethyl groups as the electron-withdrawing substituents shows the largest deformation degrees when irradiated with 488 and 532 nm light, respectively.

Post-polymerization modification reactions of poly(glycidyl methacrylate)s

Single and multiple post-polymerization modifications of poly(glycidyl methacrylate) scaffold through the nucleophilic ring-opening reactions of the pendent epoxide groups are described.

A facile synthetic strategy to polysiloxanes containing sulfonyl side groups with high dielectric permittivity

Novel polysiloxanes containing sulfonyl side groups with high dielectric permittivity by thiol–ene post-polymerization reactions are presented.

Clickable Poly(ionic liquids): A Materials Platform for Transfection.

The potential applications of cationic poly(ionic liquids) range from medicine to energy storage, and the development of efficient synthetic strategies to target innovative cationic building blocks is an important goal. A post-polymerization click reaction is reported that provides facile access to trisaminocyclopropenium (TAC) ion-functionalized macromolecules of various architectures, which are the first class of polyelectrolytes that bear a formal charge on carbon. Quantitative conversions of polymers comprising pendant or main-chain secondary amines were observed for an array of TAC derivatives in three hours using near equimolar quantities of cyclopropenium chlorides. The resulting TAC polymers are biocompatible and efficient transfection agents. This robust, efficient, and orthogonal click reaction of an ionic liquid, which we term ClickabIL, allows straightforward screening of polymeric TAC derivatives. This platform provides a modular route to synthesize and study various properties of novel TAC-based polymers.

Modular Fabrication of Polymer Brush Coated Magnetic Nanoparticles: Engineering the Interface for Targeted Cellular Imaging.

Development of efficient and rapid protocols for diversification of functional magnetic nanoparticles (MNPs) would enable identification of promising candidates using high-throughput protocols for applications such as diagnostics and cure through early detection and localized delivery. Polymer brush coated magnetic nanoparticles find use in many such applications. A protocol that allows modular diversification of a pool of parent polymer coated nanoparticles will lead to a library of functional materials with improved uniformity. In the present study, polymer brush coated parent magnetic nanoparticles obtained using reversible addition-fragmentation chain transfer (RAFT) polymerization are modified to obtain nanoparticles with different "clickable" groups. In this design, trithiocarbonate group terminated polymer brushes are "grafted from" MNPs using a catechol group bearing initiator. A postpolymerization radical exchange reaction allows installation of "clickable" functional groups like azides and maleimides on the chain ends of the polymers. Thus, modified MNPs can be functionalized using alkyne-containing and thiol-containing moieties like peptides and dyes using the alkyne-azide cycloaddition and the thiol-ene conjugation, respectively. Using the approach outlined here, a cell surface receptor targeting cyclic peptide and a fluorescent dye are attached onto nanoparticle surface. This multifunctional construct allows selective recognition of cancer cells that overexpress integrin receptors. Furthermore, the approach outlined here is not limited to the installation of azide and maleimide functional groups but can be expanded to a variety of "clickable" groups to allow nanoparticle modification using a broad range of chemical conjugations.

Post-polymerization functionalization of epoxide-containing copolymers in trifluoroethanol for synthesis of polymer-drug conjugates

Abstract Post-polymerization functionalization is a critical tool in preparing functional materials. The critical aspects of post-polymerization reactions are high yields, short reaction times, simple purification, near stoichiometric amounts of reactants, and facile reaction conditions. Polymeric epoxides (i.e. poly(glycidyl methacrylate)) represent an underutilized class of functionalized polymers due to long reaction times, high temperatures, and large excess of reactants to drive the reaction to high conversion in a reasonable time frame. In this manuscript we describe the use of a novel solvent trifluoroethanol (TFE) for the ring opening of amines with poly(glycidyl methacrylate). We demonstrate that TFE gives faster reaction times and higher yields than traditional solvents used for the ring opening reaction. We utilized TFE to prepare dual functionalized polymers that could be “clicked” using strain promoted azide alkyne cycloaddition and an amine-bearing drug ring opening of the polymeric backbone.

INSIGHTS INTO THE PREPARATION OF VINYL POLYBUTADIENE VIA COBALT-BASED CATALYST: TUNING ITS PROPERTIES BY THIOL-ENE MODIFICATION OF VINYL GROUP

ABSTRACTElastomers with pendant alkenyl functionality can be easily modified using different types of postpolymerization reactions that lead to improved properties. This investigation reports the preparation of polybutadiene (PB) with control vinyl content by Co-based catalyst followed by modification of vinyl functionality via thiol-ene reaction. In this case, the polymerization of butadiene was carried out in cyclohexane using cobalt octanoate (Co[oct]2) in combination with diethylaluminium chloride (DEAC) and triethylaluminium (TEAL) as cocatalysts. The effects of different parameters, such as the concentration of catalyst and cocatalyst, monomer concentration, and reaction temperature on polymerization of butadiene (BD), were evaluated and optimized to obtain the desired vinyl content in the polymer. The microstructures in PB were investigated by 1H nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy analyses. Molecular weights and dispersity (Ð) of the polymers were determined by gel permeation chromatography analysis. The viscosity average molecular weight was calculated from the intrinsic viscosity [η] using the Mark-Houwink equation. Synthesized vinyl-PB was modified by the thiol-ene reaction using benzyl mercaptan as thiolating agent and 2,2′-azobis(isobutyronitrile) as an initiator. Thiol-ene modification was confirmed by 1H NMR analysis. Surface characteristics of thiol-modified PB were characterized by goniometer. Thiol-ene–modified PB showed greatly improved adhesive strength in metal–rubber bonding, as determined by lap shear test.

Reversible Complexation of Iminophenylboronates with Mono- and Dihydroxy Methacrylate Monomers and Their Polymerization at Low Temperature by Photoinduced ATRP in One Pot

The unique ability of boronic acids to form reversible covalent linkages to 1,2- and 1,3-diols creating boronate ester rings and the pH-sensitiveness of their dissociation have stimulated the development of boron-containing polymers having phenylboronate moieties intended to be detached by competitive binding of sugars. Typically, they are synthesized by postpolymerization reactions on hydroxy-functional polymers, which cannot guarantee a quantitative functionalization, or from monomers containing the phenylboronate moiety synthesized through multiple reaction/separation/purification steps. A handy strategy for the synthesis of monomers containing an iminophenylboronate (IPB) side-chain moiety derived from glycerol monomethacrylate (GMA) or 2-hydroxyethyl methacrylate (HEMA) and their polymerization in one pot is presented, which solves these issues and is flexible enough to be extended to a variety of hydroxy-functional monomers. First, a family of IPB methacrylates was synthesized through complexation o...

Anionic flow polymerizations toward functional polyphosphoesters in microreactors: Polymerization and UV-modification

The polymerization of cyclic phosphates to poly(phosphoester)s, PPEs, is optimized for chip-based microreactors under continuous flow conditions. The anionic ring-opening polymerization of 2-isobutyoxy-2-oxo-1,3,2-dioxaphospholane (iBP) via the use of two organocatalytic systems allowed to polymerize to nearly quantitative monomer conversion within 10 or 3min, respectively at a reaction temperature of 40°C. Further, the optimized polymerization protocol was applied to 2-butenoxy-2-oxo-1,3,2-dioxaphospholane (BP) which yields a polymer that carries an alkene functionality per monomer repeating unit. This material can be postmodified in an UV-induced radical thiol–ene reaction, which was also shown to proceed with very high efficiency under UV-flow conditions. Eventually, both reactions were coupled in a two-stage reactor setup, showing that the thermally-activated polymerization can be coupled with high efficiency to the UV-activated post-polymerization modification reaction. The introduced reactor setup can in the future be used to produce and screen a broad variety of functional PPE materials with various functionalities and physical properties.

Improving the comprehensive performances of phosphonic acid functionalized poly(ether sulfone) by compositing with 1H-1,2,3-triazol-4-yl functionalized poly(ether sulfone)

The comprehensive performances of phosphonic acid functionalized poly(ether sulfone) (PES-PA) are improved by compositing with 1H-1,2,3-triazol-4-yl functionalized poly(ether sulfone) (PES-Tri). The PES-PA and PES-Tri are synthesized via the nucleophilic aromatic substitution (SNAR) polycondensation, respectively, of diethyl 2,5-dihydroxyphenylphosphonate and 4,4′-difuorodiphenylsulfone and of bisphenol A and 3,3′-diethynyl-4,4′-difluorodiphenylsulfone, and followed by hydrolysis or post-polymerization click reaction and deprotection reaction. In addition, two functionalized monomers, diethyl 2,5-dihydroxyphenylphosphonate and 3,3′-diethynyl-4,4′-difluorodiphenylsulfone are synthesized. Best comprehensive performances are achieved in the composite membrane consisting of 80% PES-PA and 20% PES-Tri by molar ratio of the functional structure units. At 100 °C and 90% RH (relative humidity), the proton conductivity of the composite membrane is 12.8 mS cm−1, about 1.8 times improvement compared with pristine PES-PA. In addition, the hydrophilicity and methanol permeability are alleviated, the water uptake is reduced from 31.3% to 16.1% at 100 °C and 90% RH and methanol permeability is reduced from 19.0 × 10−8 cm2 s−1 to 0.79 × 10−8 cm2 s−1 at 30 °C.

Encapsulation of a hydrophobic drug in polyphosphate-based nanocarriers

Event Abstract Back to Event Encapsulation of a hydrophobic drug in polyphosphate-based nanocarriers Stéphanie Vanslambrouck1, Benoît Clément1, Raphaël Riva1, Bernard Ucakar2, Véronique Préat2, Mick Gagliardi3, Daniel G. Molin3, Guy Broze1, Leo H. Koole4, Philippe Lecomte1 and Christine Jérôme1 1 University of Liege, Center for Education and Research on Macromolecules, Belgium 2 Université catholique de Louvain, Louvain Drug Research Institute, Pharmaceutics and Drug Delivery, Belgium 3 Maastricht University, Faculty of Health, Medicine and Life Science, Department of Physiology, Netherlands 4 Maastricht University, Faculty of Health, Medicine and Life Science, Department of Biomedical Engineering/Biomaterials Sci., Netherlands Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications, especially for drug delivery systems. In contrast to aliphatic polyesters, such as poly(ε-caprolactone) and poly(lactide), the pentavalency of phosphorus atom allows the easy modification of the polyphosphate properties by simply adjusting the nature, the length and the functionality of the polyphosphate pendant groups. Poly(ethylene glycol) (PEG)-b-polyphosphate block copolymers made of hydrophilic PEG and hydrophobic polyphosphates are amphiphilic copolymers prone to self-assemble in aqueous medium into micelles. In order to enhance the encapsulation of hydrophobic drugs, a series of amphiphilic PEG-b-polyphosphate copolymers were synthesized by organocatalyzed ring-opening polymerization of cyclic phosphates and, in some case, followed by thiol-ene click post-polymerization reactions between the pendant vinyl group of a preformed polyphosphate block and some thiols (i.e. dodecyl thiol and tocopherol thiol). Our work aims at changing the nature of the pendant groups of the polyphosphate block to investigate the influence of this structural modification (i) on the size of the micelles, (ii) on the critical aggregation concentration (CAC), (iii) on the loading of an hydrophobic model drug (i.e. ketoconazole) and, finally, (iv) on the release of this drug. As biomedical applications are foreseen, the cytotoxicity of these PEG-b-polyphosphate copolymers were also evaluated by live/dead cell viability assays. BioMIMedics, Interreg EMR IV-A Consortium Keywords: Drug delivery, polymer, Biodegradable material Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Self-assembling micellar systems Citation: Vanslambrouck S, Clément B, Riva R, Ucakar B, Préat V, Gagliardi M, Molin DG, Broze G, Koole LH, Lecomte P and Jérôme C (2016). Encapsulation of a hydrophobic drug in polyphosphate-based nanocarriers. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.00879 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Stéphanie Vanslambrouck Benoît Clément Raphaël Riva Bernard Ucakar Véronique Préat Mick Gagliardi Daniel G Molin Guy Broze Leo H Koole Philippe Lecomte Christine Jérôme Google Stéphanie Vanslambrouck Benoît Clément Raphaël Riva Bernard Ucakar Véronique Préat Mick Gagliardi Daniel G Molin Guy Broze Leo H Koole Philippe Lecomte Christine Jérôme Google Scholar Stéphanie Vanslambrouck Benoît Clément Raphaël Riva Bernard Ucakar Véronique Préat Mick Gagliardi Daniel G Molin Guy Broze Leo H Koole Philippe Lecomte Christine Jérôme PubMed Stéphanie Vanslambrouck Benoît Clément Raphaël Riva Bernard Ucakar Véronique Préat Mick Gagliardi Daniel G Molin Guy Broze Leo H Koole Philippe Lecomte Christine Jérôme Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Influence of the Grafting Density on the Self-Assembly in Poly(phenyleneethynylene)-g-poly(3-hexylthiophene) Graft Copolymers

Conjugated graft copolymers consisting of a chiral poly(phenyleneethynylene) (PPE) backbone and poly(3-hexylthiophene) side chains (P3HT) with different grafting degrees were synthesized. While PPE was prepared by classical Sonogashira couplings, the end-functionalized P3HT was prepared by a controlled Kumada catalyst transfer polycondensation (KCTP) allowing the installation of an acetylene end group. After some postpolymerization reactions on the PPE to introduce azide groups, the P3HT was clicked to the PPE through the CuAAC coupling reaction. Subsequently, the (chiral) self-assembly of these materials was studied by means of UV–vis and CD spectroscopy, AFM, and DSC. Finally, fluorescence spectroscopy is used to study the quenching of the PPE fluorescence by P3HT.

Polyethylene-Based Block Copolymers for Anion Exchange Membranes

Block copolymer membranes with a semicrystalline polyethylene component were prepared by anionic polymerization and postpolymerization functionalization reactions. Polybutadiene-b-poly(4-methylstyrene) (PB-b-P4MS) precursors with four different block compositions and 92–95% 1,4-content in the polybutadiene block were produced by living anionic polymerization in a nonpolar solvent. The polybutadiene block was subsequently hydrogenated to prepare a polyethylene block, and the hydrogenated block copolymers were then brominated at the arylmethyl group of the P4MS block. Subsequent quaternization reaction with trimethylamine led to the anion exchange membranes. The degree of crystallinity in the polyethylene block was determined by differential scanning calorimetry to be approximately 24–27%. The postpolymerization modification reactions were examined by 1H NMR and IR spectroscopy. The amount of quaternary ammonium groups was quantified by ion exchange capacity (IEC) measurements. Membranes with IEC’s ranging ...

Biocompatible chiral monolithic stationary phase synthesized via atom transfer radical polymerization for high performance liquid chromatographic analysis

Novel biocompatible chiral monolithic stationary phase was prepared by reverse and direct atom transfer radical polymerization (ATRP) methods. By taking advantages of the controlled/living property of ATRP method, the chiral monolith was prepared by reverse ATRP (RATRP) firstly. An attractive feature of RATRP is the prepared polymer containing a terminal radically transferable atom that can initiate another post-polymerization reaction by direct ATRP. Then, the biocompatible poly(hydroxyethyl methacrylate) (PHEMA) was grafted on the surface of the chiral monolith by direct ATRP as a diffusion barrier for proteins. This biocompatible chiral monolith was successfully used as restricted access stationary phase for determination of enantiomers in biological samples with direct injection by high-performance liquid chromatography (HPLC).

Biocompatible Glycopolymer Nanocapsules via Inverse Miniemulsion Periphery RAFT Polymerization for the Delivery of Gemcitabine.

Encapsulation of hydrophilic cancer drugs in polymeric nanocapsules was achieved in a one-pot process via the inverse miniemulsion periphery RAFT polymerization (IMEPP) approach. The chosen guest molecule was gemcitabine hydrochloride, which is used as the first-line treatment of pancreatic cancer. The resulting nanocapsules were confirmed to be ∼200 nm, with excellent encapsulation (∼96%) and loading (∼12%) efficiency. Postpolymerization reaction was successfully conducted to create glyocopolymer nanocapsules without any impact on the loads as well as the nanocapsules size or morphology. The loaded nanocapsules were specifically designed to be responsive in a reductive environment. This was confirmed by the successful disintegration of the nanocapsules in the presence of glutathione. The gemcitabine-loaded nanocapsules were tested in vitro against pancreatic cancer cells (AsPC-1), with the results showing an enhancement in the cytotoxicity by two fold due to selective accumulation and release of the nanocapsules within the cells. The results demonstrated the versatility of IMEPP as a tool to synthesize functionalized, loaded-polymeric nanocapsules suitable for drug-delivery application.

Facile method towards functionalization of partially fluorinated polyarylethers via sequential post-polymerization modification

A novel partially fluorinated arylene vinylene ether (FAVE) polymer containing ester groups was synthesized, which was used to prepare three reactive FAVE polymers containing carboxylic acid groups, alcohol groups, and acid chloride groups, respectively. Post-polymerization modifications of the FAVE polymer's carboxylic acid groups (via a DCC coupling procedure with the desired alcohol), alcohol groups (via DCC coupling or an acid chloride esterification procedure with the desired carboxylic acid or acid chloride), and acid chloride groups (via an optimized nucleophilic substitution reaction with the desired alcohol or amine) were successfully performed. Several examples have been successfully prepared to demonstrate the versatility of these developed modification methods. FAVE polymers have been prepared with NHS active ester groups, Disperse Red 1 chromophores, benzyl bromide groups, aryl trifluorovinyl ether groups, ATRP initiator groups, vinyl groups, propargyl groups, Disperse Orange 3 chromophores, and benzaldehyde groups. In most cases, analytical data are consistent with a quantitative conversion of the reactive or functional groups. It is demonstrated that no degradation of the FAVE polymer matrix occurs after multistep post-polymerization modification reactions.