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Our group recently developed a family of side-chain amino acid functionalized poly(S-alkyl-L-homocysteines), Xaa-CH (Xaa = generic amino acid), which possess the ability to form environmentally responsive coacervates in water. In effort to further study how molecular structure affects polypeptide coacervate formation, we prepared side-chain amino acid functionalized poly(S-alkyl-rac-cysteines), Xaa-rac-C, via post-polymerization modification of poly(dehydroalanine), ADH. The use of the ADH platform allowed straightforward synthesis of a diverse range of side-chain amino acid functionalized polypeptides via direct reaction of unprotected L-amino acid 2-mercaptoethylamides with ADH. Despite their differences in main-chain structure, we found that Xaa-rac-C can form coacervates with properties similar to those seen with Xaa-CH. These results suggest that incorporation of side-chain amino acids onto polypeptides may be a way to generally favor coacervation. The incorporation of L-methionine in Met-rac-C allowed preparation of coacervates with improved stability against high ionic strength media. Further, the presence of additional thioether groups in Met-rac-C resulted in an increased solubility change upon oxidation allowing facile reversible redox switching of coacervate formation in aqueous media.