Hybrid acrylic-polyimide latexes from miniemulsion polymerisation

摘要

A rigid polyimide (PI) was dissolved in acrylic monomers (methyl methacrylate, n-butyl acrylate) as a hydrophobe to form miniemulsions stabilized by a mixture of sodium dodecyl sulfate and Triton, with droplets size in the range 100-300 nm, and PI concentration up to about 30% by weight, which corresponds to its limit of solubility. Upon polymerization initiated with ammonium persulfate, the particle size tends to decrease to the range 80-250 nm. From these hybrid latexes, clear yellowish films were obtained with two glass transitions: one close to that of polybutylacrylate (T_g = -50 ℃) and the second between 15 and 40 ℃, depending on PI concentration. PI causes a reinforcement of the mechanical properties at room temperature. This reinforcement is enhanced through an appropriate thermal treatment.