MOLECULAR ASPECTS OF LATEX FILM FORMATION - AN ENERGY-TRANSFER STUDY

Poly(butyl methacrylate) (PBMA) latex labeled with either phenanthrene or anthracene derivatives in low concentrations (1 or 2 mol %) was prepared by semicontinuous emulsion polymerization. The latex film formation process was studied by analysis of the nonradiative energy transfer from phenanthrene (donor) to anthracene (acceptor). Initially, when the latex film dries, there is little energy transfer, indicating that the particles conserve their individual identity. With increasing time at temperatures above the glass transition temperature of PBMA, the extent of energy transfer increases. This is a clear indication that interdiffusion of polymer chains across particle boundaries occurs. The diffusion coefficient D of the polymer was evaluated by using models based upon Fick’s second law. In each sample, the magnitude of D decreases with time. Initial D values increase with increasing temperature, taking values between 1 × 10−14 to 1 × 10−18 cm2/s, yielding an apparent activation energy of 38 kcal/mol. The diffusion data also fit well to the Williams-Landel-Ferry equation. The results demonstrate the great potential of fluorescence techniques in the study of polymer diffusion processes during latex film formation. © 1990, American Chemical Society. All rights reserved.