Surface dynamics during latex film formation

Surface dynamics during latex film formation has been investigated theoreti cally and experimentally by atomic force microscopy. The peak-to-valley dis tance, y(t), of the latex particles in the surface plane of the latex film decayed exponentially with time during film formation. A theoretical relati onship between y(t) and time, t, is given by y(t) = y(0) exp[-t/tau], where y(0) is the value of y(t) when t is zero. tau is a characteristic constant related to the nature of polymer, the particle radius, the surface diffusi on coefficient and the temperature. The relationship between the surface di ffusion coefficient, D-s, y(0), the radius of the latex particles, R, tempe rature, T, and t is given approximately by D-s = 1.2 x 10(-20)y(0)(2)[2R - y(0)]T-2/tau (cm(2)/s), where the units are manometers for y(0) and R, kelv in for temperature, and seconds for tau. By measuring the decay of y(t) wit h time, the surface diffusion coefficient can be obtained. The surface diff usion coefficient for a poly(methyl methacrylate-co-butylacrylate) (50:50) copolymer latex film was found to be A x 10(-13) cm(2)/s, A is temperature- dependent. (C) 2000 Elsevier Science S.A. All rights reserved.