聚偏氟乙烯（Polyvinylidene fluoride, PVDF）具有化学稳定性好、抗氧化性强、机械强度高和耐热耐辐射等特点，是一种重要的微孔膜材料。热致相分离（Thermally induced phase separation, TIPS）法是一种制备微孔膜的新技术，制备出的微孔膜具有强度高、孔径分布窄且孔隙率高等优点。本课题组在2006年成功发现唯一一个能与PVDF发生液-液相分离的稀释剂－二苯甲酮（DPK）。然而该体系的液－液相分离区较窄，在工程通常采用的30 wt%的聚合物浓度条件下体系发生的是固-液相分离。本文在DPK的基础上，从分子结构出发，探讨与DPK有类似的对称苯环结构的稀释剂的极性以及它们与PVDF的相互作用强弱，筛选出碳酸二苯酯（DPC）这一新型稀释剂。TIPS相图显示液-液相分离区有了较大的拓宽（0～56 wt%），实现了在30 wt%聚合物浓度下获得双连续膜孔结构。加入非溶剂1,2-丙二醇（PG）与DPK组成混合稀释剂，可降低体系的相容性，扩大体系的液-液相分离区，随混合稀释剂中PG与DPK的质量比从1/9逐渐增加至2/3时，偏晶点从30 wt%移至约70 wt%，当聚合物浓度为30 wt%且PG与DPK的质量比为3/7时，可获得双连续结构。根据TIPS的特点以及制膜体系的特性，自行开发了PVDF中空纤维膜的纺丝装置，实现了TIPS法PVDF中空纤维膜的连续可控制备。同时还开发了集萃取和精馏于一体的稀释剂萃取和回收装置，实现了稀释剂和萃取剂酒精的循环再利用。通过对PVDF中空纤维膜制备配方和工艺的研究，发现稀释剂配比α、聚合物浓度β、空气间隙lgd和水浴温度twb是影响PVDF中空纤维膜微观结构与性能的主要因素，也是纺丝过程的控制变量。通过共混亲水性聚合物对PVDF中空纤维膜进行亲水化改性，考察了3种亲水性聚合物A、B和C与PVDF的相容性以及它们对PVDF中空纤维膜亲水性的影响。DSC、热台显微镜和SEM照片表明，只有亲水性聚合物C与PVDF具有较好的相容性。进一步优化条件，确定以DPC为稀释剂，且通过共混亲水性聚合物C进行亲水化改性，可制备出了综合性能优异的PVDF中空纤维膜，纯水通量和拉伸强度分别可达356.62 L/m2•h(-0.02 MPa)和3.22 MPa。

Polyvinylidene fluoride (PVDF) is widely used to prepare microprous membrane due to its good mechanical strength and high chemical resistance to strong acid, alkali, oxidant, heat and radiation. Thermally induced phase separation (TIPS) method is a new technology to prepare microporous membranes. The membranes prepared via TIPS method have several advantages, such as good mechanical strength, narrow pore size distribution and high porosity. The key point of the preparation of PVDF membranes via TIPS method is the selection of suitable diluent. PVDF/diluent system is expected to undergo liquid-liquid (L-L) phase separation during the TIPS process, which can bring about the formation of bicontinuous structure. L-L phase separation phenomenon was first found in PVDF/diphenyl ketone (DPK) system in 2006. However, the L-L phase separation region was too narrow and only solid-liquid (S-L) phase separation occurred when polymer concentration reached or exceeded 30 wt%. In the dissertation here, a new solvent of diphenyl carbonate (DPC) was used to prepare PVDF membranes via TIPS method, which has a homologous symmetrical diphenyl structure with DPK. The phase diagram showed that the monotectic point was successfully extended to higher polymer concentration of about 56 wt%. Polymer concentration and quenching temperature had remarkably effect on the morphology and tensile strength of the resulting membranes. As the increase of the polymer concentration, the cross-section morphology changed from the bicontinuous structure to cellular structure, till to compact spherulitic structure. Moreover, the pore size and porosity decrease, however, the tensile strength increased. When the polymer concentration was less than the monotectic point, the pore size increased with the increase of the quenching temperature. When the polymer concentration was more than the monotectic point, smaller and more uniform spherulitic particles were found in the cross-section of PVDF membrane quenched at lower temperature. The addition of PG non-solvent could lower the compatibility of system and then extend the L-L phase separation region to higher polymer concentration. As the PG/DPK mass ratio increased from 1/9 to 2/3, the monotectic point shifted from 30 wt% to 70 wt%. And a bicontinuous structure could be obtained when polymer concentration was 30 wt% and PG/DPK mass ratio was 3/7. Based on the characteristic of TIPS method and the casting solution, a spinning plant of PVDF hollow fiber membrane was designed by ourselves, which made the production process of PVDF hollow fiber membranes continuously controllable. Meanwhile, a plant having two functions of extraction and rectification was also designed to recycle the diluent and the ethanol extractor. DPK mass fraction in cosolvent (α), polymer concentration (β), air gap (lgd) and water bath temperature (twb) were designed as the variables in the spinning process. By increasing α, the membrane cross-sectional morphology changed from cellular structure to compact spherulitic structure, and the porosity also decreased. As the increase of β, the membrane cross-sectional morphology also changed from the cellular structure to compact structure, and the pore sizes at the inner and outer surface decreased and the porosity also decreased. As the increase of lgd, the membrane cross-sectional structure became denser, even to form skin layer, however, the inner surface structure changed little. As the increase of twb, the membrane cross-sectional morphology changed little, however, the spherulite and the spherulitic gap increased slightly. With decrease of α, β and lgd and the increase of twb, the pure water flux of the PVDF hollow fiber membranes increased. And with the decrease of α and twb and the increase of βand lgd, the tensile strength of the PVDF hollow fiber membranes increased. Three kinds of hydrophilic polymers (A, B and C) were used to improve the hydrophilicity of PVDF hollow fiber membranes by blending. The influence on miscibility and hydrophilicity of PVDF blending these three kinds of hydrophilic polymers were studied. DSC, opitical microscope and SEM results showed that only the hydrophilic polymer C displayed good miscibility with PVDF. With the increase of the content of the hydrophilic polymer C, the contact angle of the PVDF hollow fiber membrane decreased, which resulted in the increase of the pure water flux, however, the tensile strength decreased. In conclusion, the PVDF hollow fiber membranes were prepared via TIPS method by using the PVDF/C blend as the membrane material and DPC as the diluent. The resulting PVDF hollow fiber membranes showed outstanding integrative properties, such as high pure water flux of 356.62 L/m2•h(-0.02 MPa) and good tensile strength of 3.22 MPa.