两亲性三嵌段PDMAEMA/PMMA聚合物共混改性PVDF膜的制备与性能表征

Preparation and characterization of amphiphilic triblock PDMAEMA/PMMA blend modified PVDF membrane

为了制备pH刺激响应型智能膜,并为膜改性提供结构可控的两亲性聚合物共混改性剂,以聚甲基丙烯酸二甲氨基乙酯(PDMAEMA)为亲水链段、聚甲基丙烯酸甲酯(PMMA)为疏水链段,通过RAFT聚合合成两亲性三嵌段聚合物PDMAEMA-b-PMMA-b-PDMAEMA(PDMD),采用1H-NMR对其化学结构进行了表征.以PDMD作为改性剂,通过NIPS法制备PVDF改性膜,采用ATR-FTIR、XPS、SEM和接触角测定仪对PDMD/PVDF改性膜的表面化学结构、微观形貌和亲水性进行了表征.结果表明:随着聚合物改性剂的增加,PDMD/PVDF改性膜表面PDMAEMA含量增加,改性PVDF膜的初始接触角由纯膜的108.9°降低至92.4°,纯水(pH 5.2)通量由纯膜的15.0 L/(m2·h)增大至250.0 L/(m2·h);并且改性膜随着纯水pH值的逐渐减小,膜通量减小,纯水pH值从11降到3时,通量从225.6 L/(m2·h)降至91.2 L/(m2·h).因此PDMD的加入改善了PVDF膜亲水性,可为pH刺激响应型智能膜的构建提供新材料.

In order to prepare a kind of pH stimulus-responsive smart membrane, the amphiphilic block copolymers PDMAEMA-b-PMMA-b-PDMAEMA（PDMD） based on hydrophilic poly（N,N-dimethylamino-2-ethyl methacrylate）（PDMAEMA） and hydrophobic poly（methylmethacrylate）（PMMA） were prepared by RAFT polymerization. The chemical structure of the polymer PDMD was characterized by1 H-NMR. PVDF modified membrane were prepared by NIPS method using PDMD as modifier agent. The surface chemical structure, rnicro morphology and hydrophilicity of PDMD/PVDF modified membrane were characterized by ATR-FTIR, XPS,SEM and contact angle measurement. The results showed that the content of PDMAEMA on the surface of PDMD/PVDF blending membrane increased with the increase of polymer modifier agent. The initial contact angle of modified PVDF membrane decreased from 108.9° to 92.4°, and the flux of pure water（pH 5.2） increased from15.0 L/（m2·h） to 250.0 L/（m2·h）. The membrane flux decreased with the decrease of pH of pure water. When the pH of pure water drops from 11 to 3, the flux decreased from 225.6 L/（m2·h） to 91.2 L/（m2·h）. Therefore,the addition of PDMD improved the hydrophilicity of PVDF membrane, which could provide new materials for the construction of pH stimulus-responsive smart membrane.