Poly[glycidyl oligo(oxyethylene)carbamate]s (PGn-EOmR′ and R-PGn-EOmR′): controlled synthesis and effects of molecular parameters (n and m), side groups (R′), and end-groups (R) on thermoresponsive properties

Abstract

The controlled syntheses of glycerol-based polymers, involving poly(glycidol) (PG)-backbones and thermoresponsive oligo(oxyethylene)-side chains, are described. The organocatalytic ring-opening polymerizations of benzyl glycidyl ether (BnGE) were performed to produce poly(benzyl glycidyl ether)s (PBnGE_ns) in which the degree of polymerization (n) was predetermined, followed by the removal of the inherent protection groups. For these polymerization/deprotection stages, the synthesis of two major types of polymers is emphasized, in which one is “pristine” PG without any specific end-groups (PG_n) and the other is the α-end functionalized PG with hydrophobic aliphatic and aromatic groups (R-PG_n). The post-modification reactions based on the addition reactions of isocyanate derivatives to the hydroxyl side groups were adopted for PG_n and R-PG_n, thus producing poly[glycidyl oligo(oxyethylene)carbamate]s with diverse structures. The structures can generally be expressed as PG_n-EO_mR′ and R-PG_n-EO_mR′, where (i) the degree of polymerization (n), (ii) the alkyl group at the periphery of the side groups (R′), (iii) the number of oxyethylene chains (m), and (iv) the α-end group (R) can be independently controlled and/or selected. The effects of the parameters/structures (i)–(iv) on the thermoresponsive properties and the supporting data for the phase transitions in aqueous media are described in detail.