Functional polymer particles via thiol–ene and thiol–yne suspension “click” polymerization

Abstract

Water-borne thiol–ene and thiol–yne polymer particles were synthesized using several alkene, alkyne, and thiol monomers in suspension thiol–ene and thiol–yne “click” polymerizations. In particular, we show that thiol–yne suspension polymerizations are possible, and that thermal initiation provides similar results as previously reported photoinitiation of thiol–ene monomers. The particles were analyzed in terms of particle size, glass transition temperature (T_g), and ability to undergo chemical functionalization. Composition and crosslink density clearly impacted the glass transition temperatures, with higher crosslink densities leading to higher T_g values. Polymer particles with excess alkene/alkyne or thiol functionality were also synthesized to examine the influence of monomer stoichiometry on particle size and thermal properties of each system. Functionalization of thiol–ene polymer particles was demonstrated using either the inclusion of an ene-functionalized chromophore during the polymerization, or post-polymerization functionalization using thiol–isocyanate chemistry.