International. A new comb-shaped fluorinated methacrylate copolymer has been synthesized and used as a reactive modifier for epoxy resins.
The chemical structure of the comb-shaped fluorinated reactive modifier (CFRM) was characterized by GPC, FTIR and 1HNMR. In addition, a random fluorinated reactive modifier (RFRM) that possessed the same chemical composition but a random structure was developed as a contrast modifier. Surface energy, surface composition and surface morphology were investigated using contact angle testing, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy.
Compared to RFRM, CFRM-modified epoxy thermosettings showed lower surface energy, higher atomic concentration of fluorine on the surface, and rougher surface morphology. CFRM-modified thermosettings possessed an even lower surface energy (18.32 mN/m) than polytetrafluoroethylene (18.50 mN/m) by only adding 0.05% by weight of fluorine component (DFHMA structural unit), indicating their high efficiency and effectiveness in improving surface hydrophobicity.
Tensile strength and glass transition tests determined by dynamic mechanical thermal analysis (DMTA) showed that both tensile strength and Tg decreased slightly by incorporating the two reactive modifiers, since the sofer segments were incorporated. And the cfRM-modified thermosettings showed a slightly lower Tg than the RFRM.
The influence of the reactive modifier on Shore D hardness as well as thermal stabilities were not significant due to low concentrations. The incorporation of CFRM was more advantageous in decreasing water absorption, while optical transmittance deteriorated. Hydrophobic epoxy resins modified with CRFM may have potential application in antifouling coatings and other occasions requiring low surface energy.
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