Polymethylene-b-Polystyrene Diblock Copolymer: Synthesis, Property, and Application

The design and synthesis of well-defined polymethylene-b-polystyrene (PM-b-PS, M-n = 1.3 x 10(4)-3.0 x 10(4) g/mol; M-w/M-n (GPC) = 1.08-1.18) diblock copolymers by the combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) was successfully achieved. The H-1 NMR spectrum and GPC traces of PM-b-PS indicated the successful extension of PS segment on the PM macroinitiator. The micellization behavior of such diblock copolymers in tetrahydrofuran were characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM) techniques. The average aggregate sizes of PM-b-PS diblock copolymers with the same length of PM segment in tetrahydrofuran solution (1.0 mg mL(-1)) increases from 104.2 nm to 167.7 nm when the molecular weight of PS segment increases. The spherical precipitated aggregates of PM-b-PS diblock copolymers with an average diameter of 600 nm were observed by AFM. Honeycomb porous films with the average diameter of 3.0 mu m and 6.0 mu m, respectively, were successfully fabricated using the solution of PM-b-PS diblock copolymers in carbon disulfide via the breath-figure (BF) method under a static humid condition. The cross-sections of low density polyethylene (LDPE)/polystyrene (PS)/PM-b-PS and LDPE/polycarbonate (PC)/PM-b-PS blends were observed by scanning electron microscope and reveal that the PM-b-PS diblock copolymers are effective compatilizers for LDPE/PS and LDPE/PC blends. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1894-1900, 2010