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5481 KiB

Open AccessArticle

Light and Temperature as Dual Stimuli Lead to Self-Assembly of Hyperbranched Azobenzene-Terminated Poly(N-isopropylacrylamide)

by Wenyan Huang, Jing Yang, Yunqing Xia, Xuezi Wang, Xiaoqiang Xue, Hongjun Yang, Guifang Wang, Bibiao Jiang, Fang Li and Sridhar Komarneni

Polymers 2016, 8(5), 183; https://doi.org/10.3390/polym8050183 - 7 May 2016

Cited by 12 | Viewed by 6608

Abstract

Hyperbranched poly(N-isopropylacrylamide)s (HBPNIPAMs) end-capped with different azobenzene chromophores (HBPNIPAM-Azo-OC₃H₇, HBPNIPAM-Azo-OCH₃, HBPNIPAM-Azo, and HBPNIPAM-Azo-COOH) were successfully synthesized by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using different azobenzene-functional initiators. All HBPNIPAMs showed a similar highly [...] Read more.

Hyperbranched poly(N-isopropylacrylamide)s (HBPNIPAMs) end-capped with different azobenzene chromophores (HBPNIPAM-Azo-OC₃H₇, HBPNIPAM-Azo-OCH₃, HBPNIPAM-Azo, and HBPNIPAM-Azo-COOH) were successfully synthesized by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using different azobenzene-functional initiators. All HBPNIPAMs showed a similar highly branched structure, similar content of azobenzene chromophores, and similar absolute weight/average molecular weight. The different azobenzene structures at the end of the HBPNIPAMs exhibited reversible trans-cis-trans isomerization behavior under alternating UV and Vis irradiation, which lowered the critical solution temperature (LCST) due to different self-assembling behaviors. The spherical aggregates of HBPNIPAM-Azo-OC₃H₇ and HBPNIPAM-Azo-OCH₃ containing hydrophobic para substituents either changed to bigger nanorods or increased in number, leading to a change in LCST of −2.0 and −1.0 °C, respectively, after UV irradiation. However, the unimolecular aggregates of HBPNIPAM-Azo were unchanged, while the unstable multimolecular particles of HBPNIPAM-Azo-COOH end-capped with strongly polar carboxyl groups partly dissociated to form a greater number of unimolecular aggregates and led to an LCST increase of 1.0 °C. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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3238 KiB

Open AccessArticle

Surface Property Modification of Silver Nanoparticles with Dopamine-Functionalized Poly(pentafluorostyrene) via RAFT Polymerization

by Ka Wai Fan and Anthony Michael Granville

Polymers 2016, 8(3), 81; https://doi.org/10.3390/polym8030081 - 14 Mar 2016

Cited by 15 | Viewed by 8652

Abstract

This research aims to synthesize a dopamine-functionalized macromolecular anchor to perform surface modification on the target nanostructures. A molecular anchor, 3,4-dichloro-1-[2-(3,4-dihydroxyphenyl)ethyl]-1H-pyrrole-2,5-dione, was successfully synthesized from dopamine and 2,3-dichloromaleic anhydride. The anchor acted as a linkage to couple the chains of poly(pentafluorostyrene) [...] Read more.

This research aims to synthesize a dopamine-functionalized macromolecular anchor to perform surface modification on the target nanostructures. A molecular anchor, 3,4-dichloro-1-[2-(3,4-dihydroxyphenyl)ethyl]-1H-pyrrole-2,5-dione, was successfully synthesized from dopamine and 2,3-dichloromaleic anhydride. The anchor acted as a linkage to couple the chains of poly(pentafluorostyrene) (PPFS) which were synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Modification was successfully performed to silver nanoparticles (AgNPs) by deposition of the dopamine-functionalized coupled PPFS onto the surface of the particles. The modified AgNPs had demonstrated improved dispersibility in organic solvent due to the hydrophobic nature of PPFS. To modify the surface chemistry of the nanoparticles further, thioglucose was grafted onto the structure of the coupled PPFS via thiol-fluoro nucleophilic substitution at the para-position of the pentafluorophenyl groups on the monomer units. The presence of sugar moieties on the coupled PPFS increased its hydrophilicity, which allowed the modified AgNPs to be readily dispersed in aqueous solvent. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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759 KiB

Open AccessArticle

ICAR ATRP of Acrylonitrile under Ambient and High Pressure

by Zhicheng Huang, Jing Chen, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymers 2016, 8(3), 59; https://doi.org/10.3390/polym8030059 - 2 Mar 2016

Cited by 23 | Viewed by 7796

Abstract

It is well known that well-defined polyacrylonitrile (PAN) with high molecular weight (M_w > 106 g·mol⁻¹) is an excellent precursor for high performance carbon fiber. In this work, a strategy for initiators for a continuous activator regeneration atom transfer [...] Read more.

It is well known that well-defined polyacrylonitrile (PAN) with high molecular weight (M_w > 106 g·mol⁻¹) is an excellent precursor for high performance carbon fiber. In this work, a strategy for initiators for a continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) system for acrylonitrile (AN) was firstly established by using CuCl₂·2H₂O as the catalyst and 2,2′-azobis(2-methylpropionitrile) (AIBN) as the thermal initiator in the presence of ppm level catalyst under ambient and high pressure (5 kbar). The effect of catalyst concentration and polymerization temperature on the polymerization behaviors was investigated. It is important that PAN with ultrahigh viscosity and average molecular weight (M_η = 1,034,500 g·mol⁻¹) could be synthesized within 2 h under high pressure. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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2441 KiB

Open AccessArticle

Comb-Type Grafted Hydrogels of PNIPAM and PDMAEMA with Reversed Network-Graft Architectures from Controlled Radical Polymerizations

by Sheng-Qi Chen, Jia-Min Li, Ting-Ting Pan, Peng-Yun Li and Wei-Dong He

Polymers 2016, 8(2), 38; https://doi.org/10.3390/polym8020038 - 1 Feb 2016

Cited by 13 | Viewed by 11801

Abstract

Dual thermo- and pH-responsive comb-type grafted hydrogels of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) and poly(N-isopropylacrylamide) (PNIPAM) with reversed network-graft architectures were synthesized by the combination of atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. Two [...] Read more.

Dual thermo- and pH-responsive comb-type grafted hydrogels of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) and poly(N-isopropylacrylamide) (PNIPAM) with reversed network-graft architectures were synthesized by the combination of atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. Two kinds of macro-cross-linkers with two azido groups at one chain-end and different chain length [PNIPAM–(N₃)₂ and PDMAEMA–(N₃)₂] were prepared with N,N-di(β-azidoethyl) 2-halocarboxylamide as the ATRP initiator. Through RAFT copolymerization of DMAEMA or NIPAM with propargyl acrylate (ProA) using dibenzyltrithiocarbonate as a chain transfer agent, two network precursors with different content of alkynyl side-groups [P(DMAEMA-co-ProA) and P(NIPAM-co-ProA)] were obtained. The subsequent azido-alkynyl click reaction of macro-cross-linkers and network precursors led to the formation of the network-graft hydrogels. These dual stimulus-sensitive hydrogels exhibited rapid response, high swelling ratio and reproducible swelling/de-swelling cycles under different temperatures and pH values. The influences of cross-linkage density and network-graft architecture on the properties of the hydrogels were investigated. The release of ceftriaxone sodium from these hydrogels showed both thermal- and pH-dependence, suggesting the feasibility of these hydrogels as thermo- and pH-dependent drug release devices. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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878 KiB

Open AccessArticle

Iron-Mediated Homogeneous ICAR ATRP of Methyl Methacrylate under ppm Level Organometallic Catalyst Iron(III) Acetylacetonate

by Jian Wu, Xiaowu Jiang, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymers 2016, 8(2), 29; https://doi.org/10.3390/polym8020029 - 26 Jan 2016

Cited by 24 | Viewed by 8704

Abstract

Atom Transfer Radical Polymerization (ATRP) is an important polymerization process in polymer synthesis. However, a typical ATRP system has some drawbacks. For example, it needs a large amount of transition metal catalyst, and it is difficult or expensive to remove the metal catalyst [...] Read more.

Atom Transfer Radical Polymerization (ATRP) is an important polymerization process in polymer synthesis. However, a typical ATRP system has some drawbacks. For example, it needs a large amount of transition metal catalyst, and it is difficult or expensive to remove the metal catalyst residue in products. In order to reduce the amount of catalyst and considering good biocompatibility and low toxicity of the iron catalyst, in this work, we developed a homogeneous polymerization system of initiators for continuous activator regeneration ATRP (ICAR ATRP) with just a ppm level of iron catalyst. Herein, we used oil-soluble iron (III) acetylacetonate (Fe(acac)₃) as the organometallic catalyst, 1,1′-azobis (cyclohexanecarbonitrile) (ACHN) with longer half-life period as the thermal initiator, ethyl 2-bromophenylacetate (EBPA) as the initiator, triphenylphosphine (PPh₃) as the ligand, toluene as the solvent and methyl methacrylate (MMA) as the model monomer. The factors related with the polymerization system, such as concentration of Fe(acac)₃ and ACHN and polymerization kinetics, were investigated in detail at 90 °C. It was found that a polymer with an acceptable molecular weight distribution (M_w/M_n = 1.43 at 45.9% of monomer conversion) could be obtained even with 1 ppm of Fe(acac)₃, making it needless to remove the residual metal in the resultant polymers, which makes such an ICAR ATRP process much more industrially attractive. The “living” features of this polymerization system were further confirmed by chain-extension experiment. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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3008 KiB

Open AccessFeature PaperArticle

Coordination Chemistry inside Polymeric Nanoreactors: Metal Migration and Cross-Exchange in Amphiphilic Core-Shell Polymer Latexes

by Si Chen, Eric Manoury, Florence Gayet and Rinaldo Poli

Polymers 2016, 8(2), 26; https://doi.org/10.3390/polym8020026 - 22 Jan 2016

Cited by 9 | Viewed by 9148

Abstract

A well-defined amphiphilic core-shell polymer functionalized with bis(p-methoxy-phenylphosphino)phenylphosphine (BMOPPP) in the nanogel (NG) core has been obtained by a convergent RAFT polymerization in emulsion. This BMOPPP@NG and the previously-reported TPP@NG (TPP = triphenylphosphine) and core cross-linked micelles (L@CCM; L = TPP, [...] Read more.

A well-defined amphiphilic core-shell polymer functionalized with bis(p-methoxy-phenylphosphino)phenylphosphine (BMOPPP) in the nanogel (NG) core has been obtained by a convergent RAFT polymerization in emulsion. This BMOPPP@NG and the previously-reported TPP@NG (TPP = triphenylphosphine) and core cross-linked micelles (L@CCM; L = TPP, BMOPPP) having a slightly different architecture were loaded with [Rh(acac)(CO)₂] or [RhCl(COD)]₂ to yield [Rh(acac)(CO)(L@Pol)] or [RhCl(COD)(L@Pol)] (Pol = CCM, NG). The interparticle metal migration from [Rh(acac)(CO)(TPP@NG)] to TPP@NG is fast at natural pH and much slower at high pH, the rate not depending significantly on the polymer architecture (CCM vs. NG). The cross-exchange using [Rh(acac)(CO)(BMOPPP@Pol)] and [RhCl(COD)(TPP@Pol)] (Pol = CCM or NG) as reagents at natural pH is also rapid (ca. 1 h), although slower than the equivalent homogeneous reaction on the molecular species (<5 min). On the other hand, the subsequent rearrangement of [Rh(acac)(CO)(TPP@Pol)] and [RhCl(COD)(TPP@Pol)] within the TPP@Pol core and of [Rh(acac)(CO)(BMOPPP@Pol)] and [RhCl(COD)(BMOPPP@Pol)] within the BMOPPP@Pol core, leading respectively to [RhCl(CO)(TPP@Pol)₂] and [RhCl(CO)(BMOPPP@Pol)₂], is much more rapid (<30 min) than on the corresponding homogeneous process with the molecular species (>24 h). Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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4446 KiB

Open AccessArticle

PEGylated Fluorescent Nanoparticles from One-Pot Atom Transfer Radical Polymerization and “Click Chemistry”

by Li Qun Xu, Ning Ning Li, Bin Zhang, Jiu Cun Chen and En-Tang Kang

Polymers 2015, 7(10), 2119-2130; https://doi.org/10.3390/polym7101504 - 23 Oct 2015

Cited by 7 | Viewed by 8391

Abstract

The preparation of PEGylated fluorescent nanoparticles (NPs) based on atom transfer radical polymerization (ATRP) and “click chemistry” in one-pot synthesis is presented. First, poly(p-chloromethyl styrene-alt-N-propargylmaleimide) (P(CMS-alt-NPM)) copolymer was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. Subsequently, the azido-containing fluorene-based polymer, poly[(9,9-dihexylfluorene)-alt-(9,9-bis-(6-azidohexyl)fluorene)] (PFC6N3), [...] Read more.

The preparation of PEGylated fluorescent nanoparticles (NPs) based on atom transfer radical polymerization (ATRP) and “click chemistry” in one-pot synthesis is presented. First, poly(p-chloromethyl styrene-alt-N-propargylmaleimide) (P(CMS-alt-NPM)) copolymer was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. Subsequently, the azido-containing fluorene-based polymer, poly[(9,9-dihexylfluorene)-alt-(9,9-bis-(6-azidohexyl)fluorene)] (PFC6N3), was synthesized via Suzuki coupling polymerization, followed by azidation. Finally, the PEGylated fluorescent NPs were prepared via simultaneous intermolecular “click” cross-linking between P(CMS-alt-NPM) and PFC6N3 and the ATRP of poly(ethylene glycol) methyl ether methacrylate (PEGMMA) using P(CMS-alt-NPM) as the macroinitiator. The low cytotoxicity of the PEGylated fluorescent NPs was revealed by incubation with KB cells, a cell line derived from carcinoma of the nasopharynx, in an in vitro experiment. The biocompatible PEGylated fluorescent NPs were further used as a labeling agent for KB cells. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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787 KiB

Open AccessArticle

Reversible-Deactivation Radical Polymerization of Methyl Methacrylate Induced by Photochemical Reduction of Various Copper Catalysts

by Jaroslav Mosnáček, Anna Kundys and Anita Andicsová

Polymers 2014, 6(11), 2862-2874; https://doi.org/10.3390/polym6112862 - 14 Nov 2014

Cited by 24 | Viewed by 8660

Abstract

Photochemically mediated reversible-deactivation radical polymerization of methyl methacrylate was successfully performed using 50–400 ppm of various copper compounds such as CuSO₄·5H₂O, copper acetate, copper triflate and copper acetylacetonate as catalysts. The copper catalysts were reduced in situ by irradiation [...] Read more.

Photochemically mediated reversible-deactivation radical polymerization of methyl methacrylate was successfully performed using 50–400 ppm of various copper compounds such as CuSO₄·5H₂O, copper acetate, copper triflate and copper acetylacetonate as catalysts. The copper catalysts were reduced in situ by irradiation at wavelengths of 366–546 nm, without using any additional reducing agent. Bromopropionitrile was used as an initiator. The effects of various solvents and the concentration and structure of ligands were investigated. Well-defined polymers were obtained when at least 100 or 200 ppm of any catalyst complexed with excess tris(2-pyridylmethyl)amine as a ligand was used in dimethyl sulfoxide as a solvent. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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1436 KiB

Open AccessArticle

Effect of Trapping Agent and Polystyrene Chain End Functionality on Radical Trap-Assisted Atom Transfer Radical Coupling

by Elizabeth M. Carnicom, Jessica A. Abruzzese, Yacouba Sidibe, Kenneth D. Myers and Eric S. Tillman

Polymers 2014, 6(11), 2737-2751; https://doi.org/10.3390/polym6112737 - 24 Oct 2014

Cited by 7 | Viewed by 8383

Abstract

Coupling reactions were performed to gauge the effect of the inclusion of a radical trap on the success of coupling reactions of monohalogenated polystyrene (PSX) chains in atom transfer radical coupling (ATRC) type reactions. The effect of both the specific radical trap chosen [...] Read more.

Coupling reactions were performed to gauge the effect of the inclusion of a radical trap on the success of coupling reactions of monohalogenated polystyrene (PSX) chains in atom transfer radical coupling (ATRC) type reactions. The effect of both the specific radical trap chosen and the structure of the polymer chain end were evaluated by the extent of dimerization observed in a series of analogous coupling reactions. The commonly used radical trap 2-methyl-2-nitrosopropane (MNP) showed the highest amounts of dimerization for PSX (X = Br, Cl) compared to coupling reactions performed in its absence or with a different radical trap. A dinitroxide coupling agent was also studied with the extent of coupling nearly matching the effectiveness of MNP in RTA (Radical trap-assisted)-ATRC reactions, while N-nitroso and electron rich nitroso coupling agents were the least effective. (2,2,6,6-Tetramethyl-piperin-l-yl)oxyl-capped PS (PS-TEMPO), prepared by NMP, was subjected to a coupling sequence conceptually similar to RTA-ATRC, but dimerization was not observed regardless of the choice of radical trap. Kinetic experiments were performed to observe rate changes on the coupling reaction of PSBr as a result of the inclusion of MNP, with substantial rate enhancements found in the RTA-ATRC coupling sequence compared to traditional ATRC. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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973 KiB

Open AccessArticle

Fed-Batch Control and Visualization of Monomer Sequences of Individual ICAR ATRP Gradient Copolymer Chains

by Dagmar R. D'hooge, Paul H. M. Van Steenberge, Marie-Françoise Reyniers and Guy B. Marin

Polymers 2014, 6(4), 1074-1095; https://doi.org/10.3390/polym6041074 - 10 Apr 2014

Cited by 61 | Viewed by 7644

Abstract

Based on kinetic Monte Carlo simulations of the monomer sequences of a representative number of copolymer chains (≈ 150,000), optimal synthesis procedures for linear gradient copolymers are proposed, using bulk Initiators for Continuous Activator Regeneration Atom Transfer Radical Polymerization (ICAR ATRP). Methyl methacrylate [...] Read more.

Based on kinetic Monte Carlo simulations of the monomer sequences of a representative number of copolymer chains (≈ 150,000), optimal synthesis procedures for linear gradient copolymers are proposed, using bulk Initiators for Continuous Activator Regeneration Atom Transfer Radical Polymerization (ICAR ATRP). Methyl methacrylate and n-butyl acrylate are considered as comonomers with CuBr₂/PMDETA (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine) as deactivator at 80 °C. The linear gradient quality is determined in silico using the recently introduced gradient deviation (<GD>) polymer property. Careful selection or fed-batch addition of the conventional radical initiator I₂allows a reduction of the polymerization time with ca. a factor 2 compared to the corresponding batch case, while preserving control over polymer properties (<GD> ≈ 0.30; dispersity ≈ 1.1). Fed-batch addition of not only I₂, but also comonomer and deactivator (50 ppm) under starved conditions yields a <GD> below 0.25 and, hence, an excellent linear gradient quality for the dormant polymer molecules, albeit at the expense of an increase of the overall polymerization time. The excellent control is confirmed by the visualization of the monomer sequences of ca. 1000 copolymer chains. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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820 KiB

Open AccessArticle

New Guanidine-Pyridine Copper Complexes and Their Application in ATRP

by Alexander Hoffmann, Olga Bienemann, Ines Dos Santos Vieira and Sonja Herres-Pawlis

Polymers 2014, 6(4), 995-1007; https://doi.org/10.3390/polym6040995 - 1 Apr 2014

Cited by 31 | Viewed by 10276

Abstract

The guanidine hybrid ligands, (tetramethylguanidine)methylenepyridine (TMGpy) and (dimethylethyleneguanidine)methylenepyridine (DMEGpy), were proven to be able to stabilize copper complexes active in the solvent-free polymerization of styrene at 110 °C using 1-phenylethylbromide as the initiator. The polymerization proceeded after first-order kinetics, and polystyrenes with polydispersities [...] Read more.

The guanidine hybrid ligands, (tetramethylguanidine)methylenepyridine (TMGpy) and (dimethylethyleneguanidine)methylenepyridine (DMEGpy), were proven to be able to stabilize copper complexes active in the solvent-free polymerization of styrene at 110 °C using 1-phenylethylbromide as the initiator. The polymerization proceeded after first-order kinetics, and polystyrenes with polydispersities around 1.2 could be obtained. Using the ligand, DMEGpy, three new copper guanidine-pyridine complexes could be synthesized and structurally characterized. Their structural characteristics are discussed. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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879 KiB

Open AccessArticle

Living Radical Polymerization via Organic Superbase Catalysis

by Lin Lei, Miho Tanishima, Atsushi Goto and Hironori Kaji

Polymers 2014, 6(3), 860-872; https://doi.org/10.3390/polym6030860 - 17 Mar 2014

Cited by 35 | Viewed by 9093

Abstract

Organic superbases reacted with alkyl iodides (R–I) to reversibly generate the corresponding alkyl radicals (R^•). Via this reaction, organic superbases were utilized as new and highly efficient organic catalysts in living radical polymerization. The superbase catalysts included guanidines, aminophosphines [...] Read more.

Organic superbases reacted with alkyl iodides (R–I) to reversibly generate the corresponding alkyl radicals (R^•). Via this reaction, organic superbases were utilized as new and highly efficient organic catalysts in living radical polymerization. The superbase catalysts included guanidines, aminophosphines and phosphazenes. Low-polydispersity polymers (M_w/M_n = 1.1–1.4) were obtained up to high conversions (e.g., 80%) in reasonably short times (3–12 h) at mild temperatures (60–80 °C) for methyl methacrylate, styrene and several functional methacrylates. The high polymerization rate and good monomer versatility are attractive features of these superbase catalysts. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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976 KiB

Open AccessArticle

Thermo-Responsive and Biocompatible Diblock Copolymers Prepared via Reversible Addition-Fragmentation Chain Transfer (RAFT) Radical Polymerization

by Kenichi Fukuda, Ryusuke Enomoto, Kazuhiko Ishihara, Yotaro Morishima and Shin-ichi Yusa

Polymers 2014, 6(3), 846-859; https://doi.org/10.3390/polym6030846 - 17 Mar 2014

Cited by 12 | Viewed by 7354

Abstract

Poly(2-(methacryloyloxy)ethyl phosphorylcholine)-b-poly(N,N-diethyl acrylamide) (PMPC_m-PDEA_n) was synthesized via reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization. Below, the critical aggregation temperature (CAT) the diblock copolymer dissolved in water as a unimer with a hydrodynamic [...] Read more.

Poly(2-(methacryloyloxy)ethyl phosphorylcholine)-b-poly(N,N-diethyl acrylamide) (PMPC_m-PDEA_n) was synthesized via reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization. Below, the critical aggregation temperature (CAT) the diblock copolymer dissolved in water as a unimer with a hydrodynamic radius (R_h) of ca. 5 nm. Above the CAT the diblock copolymers formed polymer micelles composed of a PDEA core and biocompatible PMPC shells, due to hydrophobic self-aggregation of the thermo-responsive PDEA block. A fluorescence probe study showed that small hydrophobic small guest molecules could be incorporated into the core of the polymer micelle above the CAT. The incorporated guest molecules were released from the core into the bulk aqueous phase when the temperature decreased to values below the CAT because of micelle dissociation. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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587 KiB

Open AccessArticle

Synthesis of Narrow Molecular Weight Distribution Norbornene-Lactone Functionalized Polymers by Nitroxide-Mediated Polymerization: Candidates for 193-nm Photoresist Materials

by Zi Jun Wang and Milan Maric

Polymers 2014, 6(2), 565-582; https://doi.org/10.3390/polym6020565 - 21 Feb 2014

Cited by 18 | Viewed by 9802

Abstract

One hundred ninety three-nanometer candidate photoresist materials were synthesized by nitroxide-mediated polymerization (NMP). Statistical copolymerizations of 5-methacryloyloxy-2,6-norboranecarbolactone (NLAM) with 5–10 mol% of controlling co-monomers (which are necessary for controlled polymerizations of methacrylates by NMP with the initiator used) in the feed, such as [...] Read more.

One hundred ninety three-nanometer candidate photoresist materials were synthesized by nitroxide-mediated polymerization (NMP). Statistical copolymerizations of 5-methacryloyloxy-2,6-norboranecarbolactone (NLAM) with 5–10 mol% of controlling co-monomers (which are necessary for controlled polymerizations of methacrylates by NMP with the initiator used) in the feed, such as styrene (ST), p-acetoxystyrene (AcOST), 2-vinyl naphthalene (VN) and pentafluorostyrene (PFS), using the unimolecular BlocBuilder^® initiator in 35 wt% dioxane solution at 90 °C were performed. As little as 5 mol% controlling comonomer in the feed was demonstrated to be sufficient to lead to linear evolution of number average molecular weight with respect to conversion up to 50%, and the resulting copolymers had dispersities of ~1.3 in most cases, an attractive feature for reducing line width roughness (LWR) in photoresists. The copolymers generally showed relatively low absorbance at 193 nm, comparable to other 193-nm candidate photoresists reported previously, despite the inclusion of a small amount of the styrenic co-monomers in the copolymer. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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RAFT Polymerization of Vinyl Esters: Synthesis and Applications

by Simon Harrisson, Xuan Liu, Jean-Noël Ollagnier, Olivier Coutelier, Jean-Daniel Marty and Mathias Destarac

Polymers 2014, 6(5), 1437-1488; https://doi.org/10.3390/polym6051437 - 20 May 2014

Cited by 106 | Viewed by 26505

Abstract

This article is the first comprehensive review on the study and use of vinyl ester monomers in reversible addition fragmentation chain transfer (RAFT) polymerization. It covers all the synthetic aspects associated with the definition of precision polymers comprising poly(vinyl ester) building blocks, such [...] Read more.

This article is the first comprehensive review on the study and use of vinyl ester monomers in reversible addition fragmentation chain transfer (RAFT) polymerization. It covers all the synthetic aspects associated with the definition of precision polymers comprising poly(vinyl ester) building blocks, such as the choice of RAFT agent and reaction conditions in order to progress from simple to complex macromolecular architectures. Although vinyl acetate was by far the most studied monomer of the range, many vinyl esters have been considered in order to tune various polymer properties, in particular, solubility in supercritical carbon dioxide (scCO₂). A special emphasis is given to novel poly(vinyl alkylate)s with enhanced solubilities in scCO₂, with applications as reactive stabilizers for dispersion polymerization and macromolecular surfactants for CO₂ media. Other miscellaneous uses of poly(vinyl ester)s synthesized by RAFT, for instance as a means to produce poly(vinyl alcohol) with controlled characteristics for use in the biomedical area, are also covered. Full article

(This article belongs to the Special Issue Controlled/Living Radical Polymerization)

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