Spontaneous, Phase-Separation Induced Surface Roughness: A New Method to Design Parahydrophobic Polymer Coatings with Rose Petal-like Morphology

摘要

While the development of polymer coatings with controlled surface topography is a growing research topic, a fabrication method that does not rely on lengthy processing times, bulk solvent solution; or secondary functionalization has yet to be identified. This study presents a facile, rapid, in situ method to develop parahydrophobic coatings based on phase separation during photopolymerization. A coinonomer resin of ethylene glycol diacrylate (EGDA) and 1H,1H,2H,2H-perfluotodecyl acrylate (PFDA) is modified with a thermoplastic additive (PVDF) to induce phase separation during polymerization. If applied to a glass substrate and photopolymerized, the EGDA/PFDA copolymer forms a homogeneous network with a single glass transition temperature (T-g) and slight hydrophobicity (theta(w) similar to 114 degrees). When the resin is modified with PVDF, phase separation occurs during photopolymerization producing a heterogeneous network with two T-g values.,The phase separation causes differences in composition and. cross-link density within the network, which leads to local variations in polymerization shrinkage across the nonconstrained material interface. Domains with higher cross-link densities shrink and contract toward the bulk material more dramatically, permitting, the formation of rough surfaces with submicron sized spheres enriched hi PVDF dispersed in a continuous matrix of EGDA/PFDA copolymer. Both the surface roughness and hydrophobic,components in the resin render these surfaces parahydrophobic with theta(w) similar to 150 degrees, high water adhesion; and a similar morphology to rose petals observed in nature.