Study on Polyacrylates and Fluoropolymer and Perfluoroalkylacrylate Modified Polyacrylates
Due to the high electro-negative properties of fluorine atom (4.0), the short atom radius (0.132nm), the short C-F bond and the high bond energy, the fluorinated polymers are distinguished particularly by their high thermal, chemical and weather resistance, unique electrical properties, excellent surface properties (especially oil and water repellency) and optical properties, the results of many applications in such as building industries (paintings and coatings), and treatment of textile.
In this paper, the interaction between polyvinylidene fluoride(PVDF) and atatic-poly methyl methacrylate(at-PMMA), the reactivity ratios and Q, e values of perfluoroalkyl methacrylate(Zonyl?TM), methyl methacrylate(MMA) and butyl acrylate(BA), and the core-shell emulsion polymerization of Zonyl TM/MMA/BA have been studied and the results were shown as below:
In chapter two, the interaction between PVDF and at-PMMA has been confirmed although such kind of force is weak. With the increment of PVDF weight fraction, the blends exhibit more heterogeneous properties and the films thus made appear to be more opaque. The difference spectra after subtraction of PVDF and PMMA showed that the interaction between carbonyl groups of PMMA and the hydrogen atoms of PVDF as the shift of u c=0 band to a lower frequency with higher PVDF content. The contact angle measurement demonstrated that the hydrophobicity against water increased with PVDF contents and that contact angles against water are larger than 90 when PVDF contents exceed 30% indicating good water repellency. The contact angles against n-hexane, however, cannot be measured because of the complete wetting of the film by n-hexane.
In chapter three, the solution polymerization was adopted to determine the reactivity ratios and Q, e values of Zonyl TM, MMA and BA. From the results one can see that the reactivity ratio of Zonyl?TM(0.88) is not that larger than that of MMA(0.10)and the e value of Zonyl TM(0.76) is only little higher than those of MMA(0.40) and BA(-0.165), which mean that although the electronegativity of perfluoroalkyl side chain exerts a great influence on the monomer reactivity, the blocking of the OCH2CH2 group dramatically reduced such kind of effect.
Therefore, it was assumed that in the solution polymerization MMA and Zonyl TM are good for copolymerization with copolymer composition almost the same as monomer feed which allows us to control the composition of copolymer by adjusting the monomer feed. However, in the emulsion polymerization of these two kinds of monomer the condition may not be as ideal as predicted because the high hydrophobicity of perfluoroalkyl group would probably induce the self-polymerization of Zonyl TM thus leading to coagulation.
In chapter four, core-shell latex with polyacrylate rich in core and fluoropolymer rich in shell was synthesized by semicontinuous emulsion polymerization with SDS/DNS-86 served as surfactants(3~4wt%) and KPS as an initiator. The polymerization temperature was about 80癈 and the solids content of latex was about 20 wt%. The stability of the final latex particles was very good but the core-shell structure of latex particles can not be clearly seen. FTIR spectra of the latex clearly show the copolymerization of Zonyl TM with MMA and BA. DSC thermograms indicate that the core and the shell have different Tg s without sharp peaks representing the extinction of transition between the core and the shell phase. The contact angles against water and cetane were all above 90 and about 50 respectively when Zonyl TM was copolymerized into latex. The results demonstrated that the core-shell latex film could only be wetted by water and cetane with difficulty when only small amount of the fluoromonomer was used (2-6wt% Zon
yl TM). By preparing core-shell latex with fluoropolymer rich in the shell phase, we can efficiently modify the surface property of the film by using only small amounts of fluorinated monomers.
At present, in the foreign countries, perfluoalkyl acrylates polymers have been successfully applied i