Thermoresponsive property of well-defined poly(N-methyl-N-n-propylacrylamide) and its copolymer architectures prepared by hydrosilylation-promoted group transfer polymerization

Abstract N-methyl-N-n-propylacrylamide (MnPAm) was polymerized using a versatile organocatalytic group transfer polymerization (GTP) system to afford the well-defined poly(N-methyl-N-n-propylacrylamide) (PMnPAm), in which a silyl ketene aminal was in-situ formed as the initiator by the B(C6F5)3-catalyzed 1,4-hydrosilylation of MnPAm and the stable hydrosilane of Me2EtSiH. After confirming the controlled/living feature for the hydrosilylation-promoted GTP system by the chain extension experiment, a series of copolymer architectures composed of the PMnPAm segment (A) as the thermoresponsive moiety and the poly(N,N-dimethylacrylamide) (PDMAm) segment (B) as the water-soluble one were synthesized using the sequential monomer addition method, i.e., AB-statistical copolymer, AB-diblock copolymer, and ABA- and BAB-triblock copolymers. The successful synthesis of PMnPAm provided careful insights into the thermoresponsive property with the cloud point temperature (Tc) around or below room temperature (29.3–14.5 °C) depending on the molecular weights. The thermoresponsive property for all of the prepared copolymer architectures of the AB-statistical copolymer, AB-diblock copolymer, and ABA- and BAB-triblock copolymers was described along with their aggregation behavior above the Tc for the thermoresponsive PMnPAm segment.