Self-diffusion in solutions of carboxylated acrylic polymers as studied by Pulsed Field Gradient NMR. 2. Diffusion of macromolecules

摘要

The diffusion constants of carboxylated acrylic copolymers in isopropanol (IPA) have been investigated using the PFG NMR technique. A range of compositions of butyl methacrylate and methacrylic acid random copolymers (BMA-MAA 100/0 through to 60/40 in 10 mol% steps) have been studied. The polymer diffusivity is two orders of magnitude slower than that for the solvent. A maximum value of G(max)=10 T/m for the gradient pulse was used to suppress solvent signal and to measure the low value of the self-diffusion coefficient for the polymers. Polymer diffusion studies at different diffusion times showed that the diffusion constant decreased with increasing diffusion time. The influence of the concentration on the polymer aggregation in solution and the influence of the BMA/MAA molar ratio on the diffusion constants of the polymer have been studied. The diffusion constant for the polymer at long diffusion times increased with mol% BMA which is similar to the short diffusion time studies. The data obtained have been discussed using published results and models for "anomalous diffusion" of macromolecules in polymer solutions.