A diffusion model of swelling of structurally labile polymeric membranes

The swelling of cryptoheterogeneous structurally labile polyvinyltrimethyls ilane membranes in isopropanol was studied experimentally and theoretically . The fraction of air inclusions in homogeneous membranes and the time to s aturation with unbound isopropanol of macroporous supports of asymmetric me mbranes were estimated. It was shown that, even though the membrane volume remains virtually constant, the swelling process cannot be described within the framework of the diffusion model with a constant diffusion coefficient . The inverse problem of identification of a parameter [the diffusion coeff icient D(t)] of the nonautonomous system from the value of the concentratio n of the diffusing species in the solid phase (the swelling value) was solv ed. In this case, the time dependence of the diffusion coefficient was trea ted as the concentration dependence D(C(t)), which was constructed and inte rpreted in terms of the mechanism of mass transfer of low-molecular-weight surfactants trough mechanically stressed cryptoheterogeneous materials.