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{"title":"Synthesis of Well-Defined Pyrrolidone-Based Homopolymersnand Stimulus-Responsive Diblock Copolymers via RAFT Aqueous SolutionnPolymerization of 2‑(<i>N</i>‑Acryloyloxy)ethylpyrrolidone","authors":"O. J. Deane (5785649), J. R. Lovett (2609164), O. M. Musa (5785652), A. Fernyhough (5785655), S. P. Armes (1370142)","doi":"10.1021/acs.macromol.8b01627.s001","DOIUrl":"https://doi.org/10.1021/acs.macromol.8b01627.s001","url":null,"abstract":"Poly­(<i>N</i>-vinylpyrrolidone) (PNVP) is a well-known,nhighly polar, nonionic water-soluble polymer. However, <i>N</i>-vinylpyrrolidone (NVP) usually exhibits strongly non-ideal behaviornwhen copolymerized with methacrylic or styrenic monomers. Moreover,nNVP is not particularly well-controlled under living radical polymerizationnconditions. For these reasons, alternative pyrrolidone-based monomersnhave been investigated. For example, the reversible addition–fragmentationnchain transfer (RAFT) polymerization of 2-(<i>N</i>-methacryloyl­oxy)­ethylpyrrolidonen(NMEP) has been recently investigated using various polymerizationnformulations. However, PNMEP homopolymers are significantly less hydrophilicnthan PNVP and exhibit inverse temperature solubility in aqueous solution.nIn the present work, we studied the RAFT aqueous solution polymerizationnof 2-(<i>N</i>-acryloyl­oxy)­ethylpyrrolidone (NAEP)nusing either AIBN at 70 °C or a low-temperature redox initiatornat 30 °C. PNAEP homopolymers are obtained in high yield (>99%)nwith good control (<i>M</i><sub>w</sub>/<i>M</i><sub>n</sub> < 1.20) for target degrees of polymerization (DP)nof up to 400 using the latter initiator, which produced relativelynfast rates of polymerization. However, targeting DPs above 400 lednto lower NAEP conversions and broader molecular weight distributions.n2-Hydroxyethyl acrylate (HEA) and oligo­(ethylene glycol) methyl ethernacrylate (OEGA) were chain-extended using a PNAEP<sub><i>x</i></sub> macro-CTA via RAFT aqueous solution polymerization, yieldingndouble-hydrophilic acrylic diblock copolymers with high conversionsn(>99%) and good control (<i>M</i><sub>w</sub>/<i>M</i><sub>n</sub> < 1.31). In addition, a PNAEP<sub>95</sub> macro-CTAnwas chain-extended via RAFT aqueous solution polymerization of <i>N</i>-isopropyl­acrylamide (NIPAM) at 22 °C. Dynamicnlight scattering (DLS) analysis indicated that heating above the lowerncritical solution temperature of PNIPAM led to so-called “anomalousnmicellization” at 35 °C and the formation of near-monodispersenspherical micelles at 40 °C. Finally, 2-(diethyl­amino)­ethylnmethacrylate (DEA) was polymerized using an <i>N</i>-morpholine-functionalizedntrithiocarbonate-based RAFT chain transfer agent and subsequentlynchain-extended using NAEP to form a novel pH-responsive diblock copolymer.nAbove the p<i>K</i><sub>a</sub> of PDEA (∼7.3), DLSnand <sup>1</sup>H NMR studies indicated the formation of well-definednPDEA-core spherical micelles.","PeriodicalId":522704,"journal":{"name":"Figshare","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147902037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}