Hydrogen-bonding-directed layer-by-layer polymer films: Substrate effect on the microporous morphology variation

The layer-by-layer (LbL) films composed of poly(4-vinylpyridine) and poly(acrylic acid) were assembled on four kinds of different substrates and their morphology variation in basic solution was comparatively studied. It was discovered that the morphology variation of the films on hydroxyl-tailored substrates was much faster than on amino-tailored substrates. Similarly, the films on carboxyl-tailored substrates could more easily yield microporous morphology than on amino-tailored substrates. The experiment results indicated that substrates played a critical role in the formation and variation process of the microporous morphology. The attractive interaction between substrates and PVP influenced the reconformation/aggregation of poly(4-vinylpyridine) chains, which led to gradually variational microporous morphology. The stronger attraction between substrates and PVP would result in slower microporous morphology variation. The investigation results in this article not only have provided some helpful experience for controlling microporous films but also have deepened the understanding of the formation mechanism of microporous morphology.