Correlation between crystallization behavior of fluorinated acrylate copolymers and the surface wetting property of their films
作者：Chen Huiqin,Zhou Gengbing,Cai Zhiqi,Pi Pihui,Wen Xiufang,Zheng Dafeng,Cheng Jiang,Yang Zhuoru
關(guān)鍵字：Fluorinated acrylate copolymers, Crystallization,Surface wetting properties, Hydrophobicity and oleophobicity
論文來(lái)源：期刊
具體來(lái)源：ACTA POLYMERICA SINICA期: 12 頁(yè): 1454-1460
發(fā)表時(shí)間：2011年
A series of fluorinated acrylate copolymers were synthesized via free radical copolymerization by using monomers of 2-(perflurooctyl) ethyl methacrylate (FOEMA) and n-alkyl acrylates (RAs) (n = 4, 8, 12, 16, 18) with various lengths of side chains. The crystalline behavior of the copolymers was characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It is found that the crystallization of acrylate copolymers is in close connection with the side-chain length of acrylates. The copolymers crystallized at room temperature when the side-chain length number n was 16 or 18, however, no crystallization was observed for the copolymers with n less than 16 under the same condition. The crystallization enthalpy changes of RA-co-FOEMA copolymers were determined from the DSC thermograms. The copolymer with n = 16 has the minimum entropy change at constant pressure compared with other three crystallized copolymers through thermodynamic calculation, which indicated this copolymer was the most ordered one. The F/C atomic ratios and composition of functional groups on the surfaces of RA/FOEMA copolymer films were determined by multifunctional photoelectron spectroscopy (XPS), and the static contact angles of n-hexadecane and water on films were measured. The F/C ratios increased from 0. 39 to 0. 71 with increase in the side-chain length of RA/FOEMA copolymers. When n was 16 or 18, the copolymers demonstrated much more composition of non-polar groups (-CF, and -CF(2)) and fewer polar groups (-C=O and -C-O-C=O) on the film surfaces, leading to the rapid increase in the n-hexadecane static contact angles on the films of copolymers. It may suggest that crystallization of hydrocarbon side-chain of copolymers can promote fluorinated component to migrate to the polymer-air interface during the process of film forming and hence improve the hydrophobicity and oleophobicity of the films.