Jong-Wook Ha

Surface properties of core-shell particles containing perfluoroalkyl acrylate in shell

The preparation and surface properties of core-shell latex particles containing fluorinated shell were considered in this study. The core-shell particles were prepared by a two-stage emulsion polymerization under kinetically controlled conditions. Alkyl methacrylate monomers having different side chain length were used as a comonomer to form the shell with perfluoroalkyl acrylate. The surface properties of the latex films produced from the core-shell particles were investigated by sliding angle measurement as well as contact angle method. Although the latex films produced from the core-shell particles exhibited similar surface free energy of 10 mN/m, there existed significant difference in the sliding angles of water and oil droplets depending on the side chain length of alkyl methacrylate comonomers.

Enhanced biocompatibility in poly(3-hexylthiophene)-based organic thin-film transistors upon blending with poly(2-(2-acetoxyacetyl)ethyl methacrylate)

Polymer blends with both biocompatibility and organic thin film transistor (OTFT) characteristics are developed by mixing a biocompatible polymer, poly(2-(2-acetoxyacetyl)ethyl methacrylate) (PHEMAAA) and a conducting polymer, poly(3-hexyl thiophene) (P3HT) at different weight ratios (i.e. P3HT/PHEMAAA = 75/25, 50/50, 25/75). Their OTFT performances were maintained at a similar level to those of pristine P3HT in spite of adding an insulator in the form of PHEMAAA. On the other hand, the biocompatibility of the P3HT/PHEMAAA blend films was found to be as good as that of PHEMAAA, indicating the successful contribution of the biocompatible polymer. In particular, these combined properties were optimized at a 25/75 weight ratio as described above. These results could be correlated with surface properties such as molecular orientation, morphology, and composition that change upon blending. Such P3HT/PHEMAAA blends are promising materials for applications in biomedical fields where materials come into contact with the human body.

Tuning Surface Properties of Poly(methyl methacrylate) Film Using Poly(perfluoromethyl methacrylate)s with Short Perfluorinated Side Chains.

To control the surface properties of a commonly used polymer, poly(methyl methacrylate) (PMMA), poly(perfluoromethyl methacrylate)s (PFMMAs) with short perfluorinated side groups (i.e., -CF3, -CF2CF3, -(CF3)2, -CF2CF2CF3) were used as blend components because of their good solubility in organic solvents, low surface energies, and high optical transmittance. The surface energies of the blend films of PFMMA with the -CF3 group and PMMA increased continuously with increasing PMMA contents from 17.6 to 26.0 mN/m, whereas those of the other polymer blend films remained at very low levels (10.2-12.6 mN/m), similar to those of pure PFMMAs, even when the blends contained 90 wt %PMMA. Surface morphology and composition measurements revealed that this result originated from the different blend structures, such as lateral and vertical phase separations. We expect that these PFMMAs will be useful in widening the applicable window of PMMA.