According to an aspect of the invention, injectable polymeric particles are provided that contain a copolymer that contains a hydroxy-acid-based repeat unit selected from a mono(hydroxy acid) unit and a poly(hydroxy acid) unit, an alkyl-ether-based repeat unit selected from a mono(alkyl ether) unit and a poly(alkyl ether) unit, and an acid-based repeat unit selected from a unit comprising multiple carboxylic acid groups and a derivative thereof. Other aspects of the invention pertain to methods of making such particles. Still other aspects of the invention pertain to injectable compositions that comprise such particles and to methods of treatment that employ such injectable compositions.