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 (CF3 and CF2) and fewer polar groups (C=O and COC=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.