Synthesis and characterization of hydrophobically-modified poly(ethylene terephthalate)

Hydrophobically-modified copolyester(MPET) was synthesized from bis(2-hydroxyethyl) terephthalate(BHET) by polycondensation using hydroxy-fluorosilicone polymer(FGX) as the modifier.Through the measurement of contact angle,the relationship between surface properties of the modified copolymer and synthesis route,viscosity and quantity of modifier was investigated.Fourier transform infrared spectroscopy,nuclear magnetic resonance spectroscopy and thermal analysis were used to examine the structure of MPET.FT-IR and 1H-NMR analysis showed that MPET with chemical bond was formed by FGX and BHET copolymerization.By adding 12% of the FGX viscosity 2 Pa.s under low vacuum,the water contact angle of the modified polyester(MPET-12) can be up to 97.2°,and the surface energy of the modified polyester is 23.4 mJ/m2,which is close to that of FGX(20 mJ/m2).Due to the small quantities of modifier,the thermal property of MPET has little change when compared with poly(ethylene terephthalate)(PET).