UC Berkeley

(Graph Presented). The controlled RAFT polymerization of a library of pH- and CO2-responsive methacryloyl sulfonamides (MSAs) that possess pKa values in the biologically relevant regime (pH = 4.5-7.4) is reported. Initial polymerizations were conducted at 70°C in DMF with 4-cyano-4-(ethylsulfanylthiocarbonylsulfanyl)pentanoic acid (CEP) or 4-cyanopentanoic acid dithiobenzoate (CTP), resulting in polymers of broad molecular weight distributions (Mw/Mn > 1.20). As well, chain extension of a poly(methacryloyl sulfacetamide) (pSAC) macro-CTA at 70°C was unsuccessful, indicating a loss of "living" chain ends during polymerization. However, by conducting the RAFT polymerization of MSAs at 30°C with 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), polymers with narrow molecular weight distributions (Mw/Mn < 1.15) and improved chain end retention were obtained. Homopolymers of each MSA derivative were synthesized, and the influence of the sulfonamide R group on monomer pKa and pH-dependent polymer solubility was determined during these studies. The facility by which these controlled poly(MSAs) can be prepared via low-temperature RAFT without the need for functional group protection and the resulting pKa-dependent pH- and CO2-responsive properties point to significant potential in areas including drug and gene delivery and environmental remediation.