| Fluorinated polyether polyols (FPO), which is an important raw material forpreparing fluorinated polyurethane (FPU)，was prepared by tetrahydrofuran andfluorinated epoxy compound (FO) which was synthesized by2,2,3,3-tetrafluoro-1-propanol and epichlorohydrin through Cationic polymerization.In order to reflect the difference of surface properties and heat resistance betweenFPU and ordinary polyurethane (PU), the epoxy compound (HO) and polyetherpolyols (HPO) were also prepared.FPU was obtained using FPO and4,4’-diphenyl methane diisocyanate (MDI). Atifrst, the reaction extent of the isocyanate in different reaction times and the optimumreaction time were measured by FT-IR, and the result shows that the optimumreaction time is90min at80°C. And then, reaction kinetics of FPU was studied byrotational rheometer. By measuring the gel time of FPO/MDI system at differentreaction temperature and according to the Flory theory, the activation energy is4.59kJ/mol. Meanwhile, PO/MDI system which are similar to FPO/MDI systemalso was investigated by using the same method, which we got the gel time and theactivation energy of PU. The results show that under the same reaction temperature,the gel time of FPU is shorter than PU, and the activation energy of FPU is0.52kJ/mol lower than PU.Futrhermore, in order to establish the relationship between surface structure andsurface properties, FPU of changing the synthesis conditions (curing temperature andthe type of catalyst) and proportion and structure of raw materials (hard segmentcontent and sequence structure of (FPO) was studied, such as the surface lfuoridecontent, enrichment and distribution uniformity by X-ray photoelectron spectroscopy(XPS) measurements, the relationship between surface fluoride content and surfacemicro phase separation by atomic force microscopy (AFM), hydrophobicity of surfaceby contact angle meter (CA). The results show that surface fluorine element isenriched and evenly distributed. The more surface fluorine content, the morehydrophobicity of surface. Since the introduction of a hydrophilic sotf segment containing fluorine element, hydrophobicity of FPU increases and the degree ofmicro-phase separation reduces. Accelerating the curing reaction rate have an effecton the migration of the fluorinated side chain to the surface，such as raising the curingtemperature or adding catalyst lead the surface fluorine content and thehydrophobicity of surface also to reduce. That adjusting the ratio of FPO and MDIand FPO sequence structure, which is lower density of fluorinated side chains andincrease the motion space of fluorinated side chains，which increas the surfacefluorine content and affected the surface properties of FPU. The contact angle of FPUis larger than that of PU, and with the increase of storage time, the contact angle ofFPU increases in the beginning and then remained stable, while the contact angle ofPU has been no significant changing.Finally, we evaluated the thermal stability of the FPU and PU. The study showsthat The lower curing temperature, the higher the efficiency of the catalyst, the morethe content of the hard segment, the higher the density of a fluorine side chain of thesotf segment, the better the thermal stability of the FPU. In addition, the thermalstability of FPU is significantly higher than PU. |
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