Synthetic polymers represent a modifiable class of materials that can serve as adjuvants to address challenges in numerous biomedical and medicinal chemistry applications including the delivery of siRNA. Polymer-based therapeutics offer unique challenges in both synthesis and characterization as compared to small molecule therapeutics. The ability to control the structure of the polymer is critical in creating a therapeutic. Reported herein, are batch and flow polymerization processes to produce amphiphilic terpolymers through a Lewis acid BF3OEt2-catalyzed polymerization. These processes focus on controlling reaction variables, which affect polymer structure in this rapid, exothermic, nonliving cationic polymerization. In addition to analytical characterization of the polymers, the in vivo activity of the polymer-siRNA conjugates is also highlighteddemonstrating that the method of synthesis does affect the in vivo activity of the resulting polymer conjugate. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1119-1129