Core-shell latexes composed of at least two different kinds of (co)polymer particles may exhibit peculiar physical and chemical properties. Fabrication of well defined core-shell nanoparticles fluorinated in the shell combined with appropriate blending of particles with different size (asymmetric blend) is a strategy to obtain required surface and bulk properties for super-hydrophobic coating applications as well as to reduce the amount of fluorochemicals for cost and environmental reasons. In this work, latexes with different particle size and core-shell structure using a BA/MMA-based copolymer for the core (BA=butyl acrylate, MMA=methyl methacrylate), and TFEMA (2,2,2-trifluoroethyl methacrylate), FNEMA (2-[(perfluorononenyl)oxyl] ethyl methacrylate) or FMA (1H,1H,2H,2Hheptadecafluorodecyl methacrylate) for the shell, as well as TSPMA (3-trimethoxysilylpropyl methacrylate) as a crosslinker and compatibility enhancer, were synthesized by seeded semi-continuous starved-feed procedure. Binary blends of these small and large fluorinated nanoparticles with different size ratios were prepared to form stable low free energy surfaces. The latter are influenced by the geometric feature of particles and crosslinking from TSPMA components. Role of particle size, composition and structure on film morphologies and surface properties were studied by using light scattering, DSC, TEM and contact angle goniometry. In order to improve the transport/diffusion of highly fluorinated comonomers in the water phase and the stablity of the final colloidal particles, several strategies were pursued such as using cationic fluorinated surfactants,1 more amphiphilic F-comonomers (surfmers, or reactive surfactants), and using a cyclodextrin2 as a carrier (phase transfer agent). Well defined core-shell fluorine-containing reactive nanoparticles, latex blends with bimodal particle size distribution and the resulting latex films were designed and prepared using TFEMA as fluorocomonomer. Improved hydropobicity is obtained on the surfaces of films without significant change of bulk properties. More highly fluorinated comonomers and non-migrating or fluorinated surfactants are needed, however, to fabricate super-hydrophobic film surfaces. Unfortunately, it is very difficult to obtain stable latex system from highly fluorinated acrylate comonomers with long perfluoroalkyl side chain such as FNEMA and FMA due to their extremely low solubility in water. Some coaglulation were generally observed upon polymerization with the procedure mentioned above.
Hydrophobic Film Surfaces from Self-Organizing Asymmetric Blends of Water-Borne Nanostructured Fluorinated Polymer Particles
CASTELVETRO, VALTER;BIANCHI, SABRINA
2009-01-01
Abstract
Core-shell latexes composed of at least two different kinds of (co)polymer particles may exhibit peculiar physical and chemical properties. Fabrication of well defined core-shell nanoparticles fluorinated in the shell combined with appropriate blending of particles with different size (asymmetric blend) is a strategy to obtain required surface and bulk properties for super-hydrophobic coating applications as well as to reduce the amount of fluorochemicals for cost and environmental reasons. In this work, latexes with different particle size and core-shell structure using a BA/MMA-based copolymer for the core (BA=butyl acrylate, MMA=methyl methacrylate), and TFEMA (2,2,2-trifluoroethyl methacrylate), FNEMA (2-[(perfluorononenyl)oxyl] ethyl methacrylate) or FMA (1H,1H,2H,2Hheptadecafluorodecyl methacrylate) for the shell, as well as TSPMA (3-trimethoxysilylpropyl methacrylate) as a crosslinker and compatibility enhancer, were synthesized by seeded semi-continuous starved-feed procedure. Binary blends of these small and large fluorinated nanoparticles with different size ratios were prepared to form stable low free energy surfaces. The latter are influenced by the geometric feature of particles and crosslinking from TSPMA components. Role of particle size, composition and structure on film morphologies and surface properties were studied by using light scattering, DSC, TEM and contact angle goniometry. In order to improve the transport/diffusion of highly fluorinated comonomers in the water phase and the stablity of the final colloidal particles, several strategies were pursued such as using cationic fluorinated surfactants,1 more amphiphilic F-comonomers (surfmers, or reactive surfactants), and using a cyclodextrin2 as a carrier (phase transfer agent). Well defined core-shell fluorine-containing reactive nanoparticles, latex blends with bimodal particle size distribution and the resulting latex films were designed and prepared using TFEMA as fluorocomonomer. Improved hydropobicity is obtained on the surfaces of films without significant change of bulk properties. More highly fluorinated comonomers and non-migrating or fluorinated surfactants are needed, however, to fabricate super-hydrophobic film surfaces. Unfortunately, it is very difficult to obtain stable latex system from highly fluorinated acrylate comonomers with long perfluoroalkyl side chain such as FNEMA and FMA due to their extremely low solubility in water. Some coaglulation were generally observed upon polymerization with the procedure mentioned above.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
