The invention provides polymer particles that are obtainable by a method selected from emulsion methods, diffusion methods and evaporation methods carried out in the presence of surface-engineering surfactant which is one or more polymer that displays a lower critical solution temperature, in aqueous media, that is between 10 to 90° C., this polymer being the polymerization product of one or more monomer selected from polymerisable alkyleneglycol acrylate monomers and polymerisable alkyleneglycol methacrylate monomers. The polymer particles can be used in controlled release applications, such as flavour release applications, fragrance release applications and biomedical applications. The invention also provides a cell support matrix comprising the polymer particles.