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A supramolecular approach to photoresponsive thermo/solvoplastic block copolymer elastomers

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Details

Original languageEnglish
Pages (from-to)7099-7108
Number of pages10
JournalMacromolecules
Volume47
Issue number20
DOIs
Publication statusPublished - 28 Oct 2014
Publication typeA1 Journal article-refereed

Abstract

With the aim of preparing supramolecular photoresponsive block copolymer elastomers, a series of ABA triblock copolymers with a poly(n-butyl acrylate) (PnBA) middle block and poly(dimethylaminoethyl methacrylate) (PDMAEMA or PDM) outer blocks were synthesized by atom transfer radical polymerization (ATRP), followed by PDM quaternization (giving PDMQ-PnBA-PDMQ) and then by ionic complexation with methyl orange (MO), an azo-containing and sulfonate-functionalized commercially available compound (giving PDMQ/MO-PnBA-PDMQ/MO). The PnBA block, which has a subambient glass transition, and the quaternized and complexed blocks, which have high glass transitions, form phase-separated soft and hard blocks, respectively. Simple elasticity tests of solvent-cast films show that the PDMQ/MO-PnBA-PDMQ/MO with hard block content between 18 and 29 wt % (as well as PDMQ-PnBA-PDMQ with 18 wt % hard block content) have significant elastomeric character. AFM and TEM (atomic force and transmission electron microscopies) of spin-coated films show a correlation between the elastomeric character and morphologies where the hard block forms a dispersed minority phase (spherical and/or short cylindrical domains). A continuous hard phase is observed for a hard block content of around 37 wt %; these materials show no significant elasticity. Reversible photoisomerization, with relatively high cis isomer content in the photostationary state, was also demonstrated.