POSS基杂化含氟丙烯酸酯共聚物涂膜的表面相分离与疏水性研究王鹏金云皮丕辉文秀芳徐守萍程江

Surface Microphase Separation and Hydrophobicity of POSS Based Fluorinated Acrylate Copolymer

采用自由基溶液聚合法成功合成了多面体低聚倍半硅氧烷（POSS）基杂化含氟丙烯酸酯共聚物,并采用核磁共振仪（NMR）和凝胶渗透色谱仪（GPC）表征了共聚物,其中POSS和含氟单体分步加入到反应中.首先将共聚物溶解到三氟三氯乙烷（F113）和乙酸乙酯的混合溶剂中配制成溶液,然后通过直接在玻璃片上滴落共聚物溶液制备了共聚物涂膜.采用扫描电子显微镜（SEM）、X-射线光电子能谱（XPS）、原子力显微镜（AFM）和接触角测量仪考察了F113和乙酸乙酯的配比对共聚物涂膜表面形貌、表面元素组成、表面粗糙度以及表面疏水性的影响.实验数据表明POSS在表面能够聚集成纳米颗粒并能极大增强涂膜表面粗糙度和疏水性.共聚物表面同时存在POSS聚集与有机相微相分离两类相分离行为,并形成了复合粗糙结构.虽然POSS和含氟段竞争迁移到表面,但是随着混合溶剂中F113的增多,涂膜表面含氟量越来越多,同时POSS在表面的聚集体越来越少,表面平均粗糙度越来越小,最终涂膜的疏水性越来越强,这说明F113有助于提升氟的趋表迁移能力,使涂膜表面含氟链段占据较多的表面空间,从而抑制了POSS在表面聚集分布.当使用纯F113作为溶剂时,共聚物涂膜的表面氟含量为45.25%,平均粗糙度为93.4 nm,此时静态水接触角最大为135.0？,表现出优异的疏水性.

The polyhedral oligomeric silsesquioxane （POSS） based fluorinated acrylate copolymer was successfully synthesized via free radical solution polymerization, which was confirmed by nuclear magnetic resonance （NMR） and gel permeation chromatography （GPC）. POSS and fluorinated monomers were separately introduced into the reaction. The copolymer solution was firstly prepared by dissolving the copolymer in a solvent mixture of 1,1,2-trichlorotrifluoroethane （F 113） and ethyl acetate （EA）. The copolymer film was then fabricated by simply drop-casting one layer of the solution on glass substrate. The influence of the volume ratio of EA to Fl13 on the microstructure morphology, element component, roughness and hydrophobicity of the film surface were investigated by scanning electron microscope （SEM）, X-ray photoelectron spectroscopy （XPS）, atomic force microscope （AFM） and contact angle instrument. The experimental results revealed that POSS aggregated on the top of the film and formed nanoscale particles, which led to rough film surface withgreat hydrophobicity. The complex and rough structure was simply fabricated due to the effect of both POSS aggregation and organic microphase separation between the fluorinated and non-fluorinated segments. Although fluorinated segments and POSS were competed to migrate onto the film surface, the content of POSS aggregation on the surface would decrease alone with the increase of Fl13 in the solvent mixture, while fluorine content was contrary to that. Consequently, both the surface roughness and surface energy decreased. The phenomenon suggested that Fl13 was helpful for fluorinated segments to migrate onto the film surface, which ensured much more room for fluorinated parts on the surface and reasonably restrained the capability of POSS aggregation on the surface. The hydrophobicity of the film increased with the content of F 113. With pure F 113 as the solvent, the contact angle of the film formed increased to the maximum of 135.0°, demonstrating well-performed hydrophobicity. At the same time, the fluorine content and average roughness of the film surface were 45.25% and 93.4 nm, respectively.