Structure and Performance of PVDF Porous Membrane Prepared by Surface Spraying DMAc/H2O-Immersion Precipitation Phase Inversion Method
-
摘要: 在刮制的聚偏氟乙烯（PVDF）铸膜液上喷雾N，N-二甲基乙酰胺/水（DMAc/H2O）混合溶液进行表面凝胶，随后将表面凝胶的液膜浸入凝固浴中进行沉淀相转变成PVDF多孔膜。考察了喷雾中DMAc的体积分数（φ（DMAc））对平板PVDF多孔膜结构和性能的影响。结果显示，随着φ（DMAc）增加，膜上表面的β晶含量逐渐减少，α晶含量逐渐增多，但是膜总体的结晶度逐渐增加，孔隙率和平均孔径先增加后减小。通过扫描电镜观察，喷雾了DMAc/H2O混合溶液的PVDF膜上表面为多孔皮层，且随着φ（DMAc）的增加，上表面球形晶粒在逐渐增加，断面由指状大孔结构转变为海绵状孔结构。当喷雾中φ（DMAc）为30%时，膜的水通量和牛血清白蛋白（BSA）截留率达到最大。
-
关键词:
- PVDF多孔膜 /
- 表面凝胶-浸没沉淀法 /
- 相转变 /
- 结晶
Abstract: Polyvinylidene fluoride (PVDF) porous membrane was prepared by a two-step method of surface gel-immersion precipitation phase inversion. First, N,N-dimethyl diamide/ H2O (DMAc/H2O) mixed solutions with different volume ratios were sprayed on the PVDF solution, leading to surface gelation of the solution films. Then, the solution films with the surface gel were immersed into the deionized water of the coagulation bath to form the porous membranes by the precipitation phase inversion. The influences of spraying different DMAC volume fractions in DMAc/H2O mixed solutions（φ（DMAc））on the structures and performances of PVDF porous membranes were investigated. Results showed that as φ（DMAc） increasing, the β crystal content on the upper surface of the membranes gradually decreased, and the α crystal content gradually increased, but the overall crystallinity of the membranes gradually increased. PVDF membranes average pore size and porosity increased firstly and then reduced with φ（DMAc） increasing, and the membrane porosity greatly affect the water flux of the membrane. It was observed by scanning electron microscope (SEM) that the upper surface of the PVDF membranes sprayed with the DMAc/H2O mixed solution became a porous skin layer, and with an increment in the DMAc ratio, the spherical crystal grains on the upper surface gradually increased, and the cross sections of the membranes changed from a finger-like macroporous structure to a sponge-like pore structure. When φ（DMAc） was 0.3 , the water flux and bovine serum albumin (BSA) rejection rate of the membrane reached the maximum. -
图 2 PVDF膜的（a）WAXD谱图和（b）DSC谱图
Figure 2. (a) WAXD spectra and (b) DSC curves of PVDF membranes
图 4 （a）PVDF膜的水通量随时间的变化；（b）PVDF膜的孔隙率、膜厚与水通量的关系
Figure 4. (a) Water flux of PVDF membrane changes with time; (b) Relationship between porosity, film thickness and water flux of PVDF membrane
表 1 PVDF膜的孔隙率和平均孔径
Table 1. Porosity and average pore size of PVDF membrane
Sample Porosity /% Average pore size/nm PM0 90 650 PM2 91 808 PM3 89 915 PM4 84 762 
下载: 导出CSV
表 2 PVDF膜的熔点、热焓和结晶度
Table 2. Melting point, enthalpy and crystallinity of PVDF membrane
Sample Tm /°C ΔH/(J·g−1) Crystallinity/% DSC WAXD PM0 162.9 34.83 33.3 39.3 PM2 162.7 35.52 33.9 39.5 PM3 162.6 35.65 34.1 41.7 PM4 162.5 36.73 35.1 46.1
下载: 导出CSV
-
[1] KAMRAN V, AMIR H, SAEDA H S, SAEED B. Preparation of modified membrane of polyvinylidene fluoride (PVDF) and evaluation of anti-fouling features and high capability in water/oil emulsion separation [J]. Journal of the Taiwan Institute of Chemical Engineers,2021,126:36-49. doi: 10.1016/j.jtice.2021.07.018 [2] 辜其隆, 陈建, 龚勇, 甘超伟, 代祖洋, 刘莎. 热处理工艺对静电纺丝制备PVDF/PMMA复合膜的力学性能的影响 [J]. 功能高分子学报,2019,32(2):225-232.GU Q L, CHEN J, GONG Y, GAN C W, DAI Z Y, LIU S. Effect of heat treatment process on the mechanical properties of PVDF/PMMA composite films prepared by electrospinning [J]. Journal of Functional Polymers,2019,32(2):225-232. [3] SAYED S M, AMIR H T. Effect of casting solution on morphology and performance of PVDF microfiltration membranes [J]. Chem Eng & Technol,2011,34(8):1328-1334. [4] ZHANG H, LU X L, LIU Z Y, MA Z, WU S, LI Z D , KONG X, LIU J J, WU C R. The unidirectional regulatory role of coagulation bath temperature on cross-section radius of the PVDF hollow-fiber membrane [J]. J Membr Sci,2018,550:9-17. [5] MA W Z, CAO Y Y, GONG F H, LIU C L, TAO G L, WANG X L. Poly(vinylidene fluoride) membranes prepared via nonsolvent induced phase separation combined with the gelation [J]. Colloids Surf A:Physicochemical and Engineering Aspects,2015,479:25-34. doi: 10.1016/j.colsurfa.2015.04.004 [6] MA B M, YANG J, SUN Q S. Influence of cellulose/[Bmim]Cl solution on the properties of fabricated NIPS PVDF membranes [J]. Journal of Materials Science,2017,52(16):9946-9957. doi: 10.1007/s10853-017-1150-2 [7] JUN T J, WANG H H, JEONG F K, LEE J, KIM J S, DRIOLI E, LEE Y M. Tailoring nonsolvent-thermally induced phase separation (N-TIPS) effect using triple spinneret to fabricate high performance PVDF hollow fiber membranes [J]. J Membr Sci,2018,559:117-126. doi: 10.1016/j.memsci.2018.04.054 [8] WEI D Y, ZHOU S Y, LI M S,XUE A, ZHANG Y, ZHAO Y, ZHONG J, YANG D. PVDF/palygorskite composite ultrafiltration membranes: Effects of nano-clay particles on membrane structure and properties [J]. Appl Clay Sci,2019,181:137-145. [9] TAO M M, LIU F, MA B R, XUE L X. Effect of solvent power on PVDF membrane polymorphism during phase inversion [J]. Desalination,2013,316:137-145. doi: 10.1016/j.desal.2013.02.005 [10] BENZ M, EULER W B, GREGORY O J. The role of solution phase water on the deposition of thin films of poly(vinylidene fluoride) [J], Macromolecules, 2002, 35: 2682-2688. [11] MA W Z, ZHANG J, WANG X L. Formation of poly(vinylidene fluoride) crystalline phases from tetrahydrofuran/N, N-dimethylformamide mixed solvent [J]. J Mater Sci,2007,43:398-401. doi: 10.1007/s11003-007-0045-9 [12] RINALDO G J. Determination of the α, β and γ crystalline phases of poly(vinylidene fluoride) films prepared at different conditions [J]. J Appl Polym Sci,2006,100:3272-3279. doi: 10.1002/app.23137 [13] ZHANG M, ZHANG A Q, ZHU B K, DU C H , XU Y Y. Polymorphism in porous poly(vinylidene fluoride) membranes formed via immersion precipitation process [J]. J Membr Sci,2008,319(1):169-175. [14] TAO M M, LIU F, XUE L X. Poly(vinylidene fluoride) membranes by an ultrasound assisted phase inversion method [J]. Ultrason Sonochem,2013,20(1):232-238. doi: 10.1016/j.ultsonch.2012.08.013 [15] SONG R, XIA G M, XHAG X Q, HE L H, ZHAO Q L, MA Z. Modification of polymorphisms in polyvinylidene fluoride thin films via water and hydrated salt [J]. J Colloid Interface Sci,2013,401:50-57. doi: 10.1016/j.jcis.2013.03.021 [16] LIN D J, CHANG C L, HUANG F M. Effect of salt additive on the formation of microporous poly(vinylidene fluoride) membranes by phase inversion from LiClO4/Water/DMF/PVDF system [J]. Polymer,2003,44(2):413-422. doi: 10.1016/S0032-3861(02)00731-0 [17] QIAN L, ZHEN L X, LI Y Y. Effects of mixed solvents and PVDF types on performances of PVDF microporous membranes [J]. Journal of Applied Polymer Science,2010,115(4):2277-2287. doi: 10.1002/app.31324 [18] KUNDU M, COSTS C M, DIAS J, ALBERTO M, JOSÉ L V, SENENTXU L M. On the relevance of the polar β-phase of poly(vinylidenefluoride) for high performance lithium-ion battery separators [J]. The Journal of Physical Chemistry C,2017,121:26216-26225. [19] ZHAO X Z, LIU C K. Efficient preparation of a novel PVDF antifouling membrane based on the solvent-responsive cleaning properties [J]. Sep Purif Technol,2019,210:100-106. doi: 10.1016/j.seppur.2018.07.088 [20] KANG G D, CAO Y M. Application and modification of poly(vinylidene fluoride) (PVDF) membranes – A review [J]. J Membr Sci,2014,463:145-165. doi: 10.1016/j.memsci.2014.03.055 [21] PEZESHK N, RANA D, NARBAITZ R M, Matsuura T. Novel modified PVDF ultrafiltration flat-sheet membranes [J]. J Membr Sci,2011,389:280-286. [22] 盖军, 冯阳阳, 柴鹏, 颜录科, 陈涛. PVDF/TiO2电纺纤维膜在光降解和油水分离方面的应用[J]. 功能高分子学报, 2021, 34(5): 483-489.GAI J, FENG Y Y, CHAI P, YAN L K, CHEN T. Application of PVDF/TiO2 electrospun fiber membrane in photodegradation and oil-water separation[J]. Journal of Functional Polymers, 2021, 34(5): 483-489. [23] XIAO T H, WANG P, YANG X, CAI X H, LU J. Fabrication and characterization of novel asymmetric polyvinylidene fluoride (PVDF) membranes by the nonsolvent thermally induced phase separation (NTIPS) method for membrane distillation applications [J]. J Membr Sci,2015,489:160-174. doi: 10.1016/j.memsci.2015.03.081 [24] LEI C H , HU B ,XU R J , CAI Q, SHI W Q. Influence of room-temperature-stretching technology on the crystalline morphology and microstructure of PVDF hard elastic film [J]. J Appl Polym Sci,2014,131:40077. -
点击查看大图
图(5) / 表(2)
计量
- 文章访问数: 63
- HTML全文浏览量: 37
- PDF下载量: 83
- 被引次数: 0
