Sequence-regulated vinyl copolymers with acid and base monomer units via atom transfer radical addition and alternating radical copolymerization

Abstract

Main- and side-chain sequence-regulated vinyl copolymers with acid and base monomer units were prepared using atom transfer radical addition (ATRA) and alternating radical copolymerization. A series of maleimide-ended sequence-regulated “oligomonomers” were prepared by ATRA of t-butyl acrylate (tBA: A_p) (i.e., a protected acrylic acid (A)) or an amine-functionalized acrylate, (2-(dimethylamino)ethyl acrylate (DMAEA: B)), and styrene (S) followed by an S_N2 reaction of furan-protected maleimide (M) anion and its deprotection. The obtained maleimide-ended oligomonomers (M–A_pS, M–SA_p, M–BS, M–SB) were copolymerized with S in alternating reversible addition–fragmentation chain transfer (RAFT) copolymerizations, resulting in main- and side-chain sequence-regulated copolymers with controlled molecular weights. After deprotection of the t-butyl group, the acid and base interactions between the copolymers were evaluated by dynamic light scattering (DLS) of the polymer solutions. All the mixtures resulted in submicron particles, and the size depended on the sequence of acid monomers in the side chains. The effects of the functionalized monomer sequences on the thermal properties were also examined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).