Dynamic light-scattering study of self-assembly of diblock copolymers in supercritical carbon dioxide

A high-pressure dynamic light-scattering (DLS) technique has been utilized to study the behavior in solution of poly(1, 1–dihydroperfluorooctylacrylate) and poly(vinyl acetate) (PFOA–b–PVAC) in supercritical carbon dioxide. The hydrodynamic–radius distribution for each species, such as unimers, micelles, and large aggregates, were determined under both isobaric and isothermal conditions over a pressure range of 9–55.2 MPa, and a temperature range of 25–75°C, respectively. The DLS results clearly showed both pressure–induced and temperature-induced dissolution and association behavior for the copolymer in supercritical carbon dioxide. Also presented are some preliminary experimental results for the micellar self–assembly of a fluorinated block copolymer, poly(2–tetrahydropyranyl methacrylate)–bpoly (1H, 1H–perfluorooctyl methacrylate) (THPMA-b-F7MA), in supercritical carbon dioxide by use of a new high–pressure cell that allows us to conduct simultaneous small–angle x–ray scattering and DLS measurements.