Hydrophobic epoxy resins modified by comb-shaped fluorinated reactive modifier

The chemical structure of the comb-shaped fluorinated reactive modifier (CFRM) was characterised by GPC, FTIR and ¹HNMR. In addition, a random fluorinated reactive modifier (RFRM) which possessed the same chemical composition but random structure was developed as a contrast modifier. Thorough performances of the modified thermosets modified with these two modifiers were investigated. Surface energy, surface composition and surface morphology were investigated by means of contact angle test, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM).

Rougher surface with CRFM

Compared with RFRM, epoxy thermosets modified with CFRM performed lower surface energy, higher fluorine atomic concentration at the surface and rougher surface morphology. The thermosets modified with CFRM possessed even lower surface energy (18.32 mN/m) than polytetrafluoroethylene (18.50 mN/m) with just adding 0.05 wt% fluorine component (DFHMA structural unit), indicating its high efficiency and effectivess in improvement of surface hydrophobicity. Tensile strength tests and glass transition determined by dynamic mechanical thermal analysis (DMTA) showed that both tensile strength and Tg decreased slightly by incorporation of the two reactive modifier since the sofer segments were incorporated. And thermosets modified with CFRM performed slightly lower Tg than that of RFRM.

Promising application in antifouling coating

The influence of the reactive modifier on Shore D hardness and thermal stabilities was not significant due to the low concentrations. The incorporation of the CFRM was more advantageous to lowering water absorption while the optical transmittance deteriorated. The hydrophobic epoxy resins modified with CRFM might have the potential application in antifouling coatings and other occasions requiring low surface energy.

The study is published in: Progress in Organic Coatings, Volume 105, April 2017, Pages 353–361