Effect Of T_g And (?)_η On Self-organization Gradient Film-formation Of Fluorinated Polyacrylates Latex Blends

Gradient polymer materials through self-organization have attracted increasing attention of many investigators recently. In molten blend system and solution blend system, the main effects on self-organizing to gradient film structure are interfacial tension, selective penetration into substrates, and so on. For emulsion system, because of the presence of emulsifier and water, the mechanism of self-organizing to formation the gradient film structure is more complex. The T_g of polymer, the time and temperature of heat treatment, the concentration and viscosity of blend phase, the interfacial tension and surface free energy of polymer, the substrate of film are all the factors of self-organizing to formation the gradient film structure. The effect of T_g and molecular weight on self-organization gradient film-formation of fluorinated polyacrylates latex blends have been studied in this paper.Two fluorinated polyacrylates latex blends (sample 1, sample 2) were prepared by blending PMMA-co-BA with two fluoroacrylate homopolymers of approximative surface free energy but different T_g, respectively. The two components of sample 2(PF₆BA/PMMA-co-BA) can film at room temperature and there is only one component of sample 1(PF₆MBA/PMMA-co-BA) can film at room temperature because of PF6MBA's high T_g (53℃). The proportion of mixture of the two samples was the same. The surface free energy of sample 1 and sample 2 which filmed at 20℃or 65℃and anneal at 105℃for different time were measured by the sessile drop method; the change of content of component were measured by ATR-FTIR and XPS; the morphology of the film surface were measured by AFM. The results showed that the gradient concentration of PF₆MBA existed in the structure of the film of sample 1 which annealed 3h at 105℃from the film-air interface to the film-glass interface. But for sample 2, the components of fluorine of two interfaces were close. Compared with that of sample 2, the two components of sample 1 were easier to self-organize on the different surface of the film during anneal process because of their different T_g. The three kinds of PF₆MBA with different molecular weight mixed with the same acrylate copolymer (PMMA-co-BA), and the three blend latexes filmed at 17℃and 25℃and annealed at 100℃andl80℃for some time. The effect of molecular weight and heat treatment on self-organization of gradient structure of the three latex blends has been detailedly studied. The results showed that, compared with the higher molecular weight fluorinated homopolymer, the lower molecular weight fluorinated homopolymer were easier to migration and self-organize to the surface of the latex blends film during film-formation and anneal process.Four kinds of copolymer were prepared with different proportion of PF3MA and BA(4/1,3/1,2/1,1.5/1). And the copolymer emulsions were mixed with different PMMA-co-BA latex. The effect of polymerization condition on polymerization and surface property of the copolymer and latex blends films were studied. It found that when the ratio of CO436 to COPS-1 was 3 to 2, the conversion ratio reached a high level and the coagulate ratio was the lowest, and there were fluorine rich in the film-air surface of the four copolymer latex membrane. Three PMMA-co-BA were prepared with different proportion(1/1.5,1/1,1/2) of monomer. The four fluorinated copolymer were mixed with PMMA-co-BA(1/2), we found the surface free energy of four blend latex films were close. PF3MA-co-BA(4/1) were mixed with different PMMA-co-BA(1/1.5,1/1,1/2), we found the ratio of MMA/BA of PMMA-co-BA could not effect the surface free energy of the latex blend membrane. PF₃MA-co-BA(4/1) were mixed with PMMA-co-BA(1/2) with different proportion, and with the content of fluorinated copolymer in latex blend membrane increased, the suface free erengy of the film decreased; and the ratio of MMA/BA of PMMA-co-BA could not affect the surface free energy of the latex blend membrane.