Semi-interpenetrating polymer networks of methyl cellulose and polyacrylamide prepared by frontal polymerization

In this work, the feasibility of frontal polymerization (FP) as an alternative and convenient technique for the preparation of semi-interpenetrating polymer networks made of methyl cellulose (MC) and crosslinked polyacrylamide (PAAm) is demonstrated. FP was performed in water and glycerol, as largely available, non-toxic solvents. Although FP occurred in both media, differences were found by comparing the samples made in the two solvents. In particular, those prepared in water are characterized by larger inhomogeneity and less reproducibility, thus accounting for the boiling effects that influence propagating polymerization fronts when water was used. The effects of the ratio among MC and PAAm, the amount of crosslinker and solvent medium were studied in terms of: influence on temperature and velocity of FP fronts, glass transition temperature (dried samples), swelling behavior, dynamic-mechanical properties (gels swollen in both water or glycerol) and tensile behavior.