High‐molecular‐weight polyisobutylenes (PIBs) and PIB networks from liquid PIBs by thiol‐ene clicking

Abstract

We report the synthesis of high-molecular-weight linear polyisobutylenes (PIBs) and PIB networks from low-molecularweight PIB by thiol-ene click chemistry. Thus, liquid allyl-telechelic PIB was reacted with small di-and tri-thiols, and the thiolated intermediates chain-extended by UV-or thermally induced free radical initiation to linear and crosslinked products. PIB networks were also prepared by crosslinking SH-telechelic PIB with a small triallyl compound. Linear products were characterized by 1 H NMR spectroscopy and GPC, and networks by FTIR spectroscopy, extractables, swelling, and permanent set. The effect of reaction conditions (nature of thiol chain extender, concentration of photo-and thermal initiators, UV radiation time, and reagent concentrations) on chain extension and crosslinking was investigated. Under well-defined conditions high-molecular-weight PIBs and tight PIB networks were prepared. Thiol-ene click chemistry provides novel thiolated PIB derivatives and is a useful strategy for the convenient preparation of high-molecular-weight rubbery PIBs and tight PIB networks from low-molecular-weight PIB precursors.

Radical–radical coupling effects in the direct-growth grafting-through synthesis of bottlebrush polymers using RAFT and ROMP

“…The deconvolution of peaks in the SEC traces was carried out by adapting a published procedure using Multiple Peak Fit in OriginPro 2018. 53 In brief, overlapping peaks were deconvoluted by assuming a Gaussian distribution, yielding the relative areas of high- and low-molar mass peaks. The percentage of coupled bottlebrush product was calculated using the following equation:where P coupling is the weight percentage of coupled bottlebrush polymer products.…”