Synthesis of amphiphilic block copolymers based on poly(dimethylsiloxane) via fragmentation chain transfer (RAFT) polymerization

Self Cite

100

Summary: The ambient temperature (20 °C) reversible addition fragmentation chain transfer (RAFT) polymerization of N‐isopropylacrylamide (NIPAAm) and acrylic acid (AA) conducted directly in aqueous media under γ‐initiation (at dose rates of 30 Gy · h−1) proceeds in a controlled fashion (typically, $\overline M _{\rm w} /\overline M _{\rm n}$ < 1.2) to near quantitative conversions and up to number‐average molecular weights of 2.5 × 105 g · mol−1 for PNIPAAm and 1.1 × 105 g · mol−1 for PAA via two water‐soluble trithiocarbonate chain transfer agents, i.e., S,S‐bis(α,α′‐dimethyl‐α″‐acetic acid)trithiocarbonate (TRITT) and 3‐benzylsulfanylthiocarbonylsulfanyl propionic acid (BPATT). The generated polymers are successfully chain extended, which suggests that the RAFT agents are stable throughout the polymerization process so that complex and well‐defined architectures can be obtained.An increase of the monomer/CTA ratio leads to an increase of the molecular weight for the RAFT polymerization of NIPAAm under γ‐radiation in water using TRITT at ambient temperature.imageAn increase of the monomer/CTA ratio leads to an increase of the molecular weight for the RAFT polymerization of NIPAAm under γ‐radiation in water using TRITT at ambient temperature.

Section: Resultsmentioning

confidence: 99%

RAFT Polymerization of N‐Isopropylacrylamide and Acrylic Acid under γ‐Irradiation in Aqueous Media

Millard

Barner

Stenzel

et al. 2006

Self Cite

100

“…HEMA a) [348] Sty [67,82,337,[349][350][351][352] a) [348] c) [300] MA [337] c) [300] BA [345,350,352,353] AEPC [353] BFA a) [354] DMAm [354] NIPAm [355] …”

Section: Tbuo-mentioning

confidence: 99%

“…d) Z substituent able to undergo fragmentation (leading to Z ¼ S-polymer). e) R 0 can be either H, alkyl, a-D-glucose, [351] hydroxypropyl cellulose, [351] b-cyclodextrin, [349,351] a branched polyester, [350] a dendrimer, [352] poly(dimethylsiloxane), [354] poly(DL-lactide), [355] or a Merrifield resin. [300] [374] StyOCOMe [240] Et 2 NSty [9,67,69,374] MA [192,375] VAc [67,376] EA [376] VAGlu [331] Sty [376] EA [376] VAc [376] StyOCOMe [240] EA [376] VAc [67] EA [376] Ph 2 N-EA [376] VAc [376] StyOCOMe [240] EA [376] Sty [9,69] AA [76] VDO [76] MA [67] NIPAm [377] DAAm [76] EA [376] [376] MMA [376] Sty [376] EA [376] VAc [376] Sty [376] Sty …”

Section: Tbuo-mentioning

confidence: 99%

Experimental Requirements for an Efficient Control of Free‐Radical Polymerizations via the Reversible Addition‐Fragmentation Chain Transfer (RAFT) Process

Favier

Charreyre

2006

435

347

Summary: Reversible addition‐fragmentation chain transfer (RAFT) polymerization is a recent and very versatile controlled radical polymerization technique that has enabled the synthesis of a wide range of macromolecules with well‐defined structures, compositions, and functionalities. The RAFT process is based on a reversible addition‐fragmentation reaction mediated by thiocarbonylthio compounds used as chain transfer agents (CTAs). A great variety of CTAs have been designed and synthesized so far with different kinds of substituents. In this review, all of the CTAs encountered in the literature from 1998 to date are reported and classified according to several criteria : i) the structure of their substituents, ii) the various monomers that they have been polymerized with, and iii) the type of polymerization that has been performed (solution, dispersed media, surface initiated, and copolymerization). Moreover, the influence of various parameters is discussed, especially the CTA structure relative to the monomer and the experimental conditions (temperature, pressure, initiation, CTA/initiator ratio, concentration), in order to optimise the kinetics and the efficiency of the molecular‐weight‐distribution control.

“…A preparative pathway to combine two different types of polymers has been introduced by covalently attaching a RAFT agent to an end-functionalized polymer. The described approaches were applied to several polymers including hydroxy-terminated poly(ethylene glycol) (PEG), [69] poly (dimethylsiloxane) [70] and poly(ethylene-co-butylene) (Kraton). [71] At CAMD, we developed a versatile approach for the synthesis of polylactide-based macroRAFT agents.…”

Section: Macromolecular Construction By Raft Agents Covalently Attachmentioning

confidence: 99%

Complex Macromolecular Architectures by Reversible Addition Fragmentation Chain Transfer Chemistry: Theory and Practice

Barner

Davis

Stenzel

et al. 2007

Self Cite

338

274

Reversible addition–fragmentation chain transfer (RAFT) chemistry can be effectively employed to construct macromolecular architectures of varying topologies. The present article explores the principle design routes to star, block, and comb polymers in the context of theoretical design criteria for the so‐called Z‐ and R‐group approaches. The specific advantages and disadvantages of each approach are underpinned by selected examples generated in the CAMD laboratories. In particular, we demonstrate how the modeling of full molecular weight distributions can be employed to guide the synthetic effort. We further explore the theory and practice of generating amphiphilic block copolymer structures and their self‐assembly. In addition, the article foreshadows how modern synthetic techniques that combine RAFT chemistry with highly orthogonal click chemistry can be employed as a powerful tool that furthers the enhancement of macromolecular design possibilities to generate block (star) copolymers of monomers with extremely disparate reactivities. Finally, the ability of RAFT chemistry to modify the surface of well‐defined nano‐ and microspheres as devices in biomedical application is detailed.magnified image