Rapid Approach to Biobased Telechelics through Two One-Pot Thiol−Ene Click Reactions

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Abstract
The application of environmentally friendly thiol−ene chemistry to the preparation of biobased telechelics is presented in this work. This methodology is based on two one-pot photoinitiated thiol−ene click processes: step-growth polymerization using a 3,6-dioxa-1,8-octanedithiol and end-group postpolymerization modification with three functional thiols: 2-mercaptoethanol, 3-mercaptopropionic acid, and 3-mercaptopropyltrimethoxysilane. We applied this approach to a potentially 100% biomass-derived monomer, allyl ester of 10-undecenoic acid (UDA). To show the generality and scope of this methodology, a series of well-defined telechelics with molecular weight ranging from 1000−3000 g/mol and hydroxyl, carboxyl, or trimethoxysilyl groups at the polymer terminus were prepared. An exhaustive 1H NMR and MALDI-TOF MS analyses demonstrates the highly end-group fidelity of this methodology being an interesting procedure for the accelerated preparation of telechelics derived from divinyl monomers. UDA-based thelechelic diol prepared using this methodology was reacted with 4,4′-methylenebis(phenylisocyanate) and 1,4-butanediol as the chain extender to obtain multiblock poly(ester urethane).