化学浴沉积制备防污自洁型PVDF/PMMA共混膜研究

使用NaOH溶液亲水改性聚偏氟乙烯(PVDF)/聚甲基丙烯酸甲酯(PMMA)共混膜,在共混膜表面化学浴沉积烷基氯硅烷,构筑微纳米结构,制备出具有超疏水能力的PVDF/PMMA共混膜,对共混膜的微观结构和性能进行了表征。结果表明,亲水改性提升了PVDF/PMMA共混膜表面烷基氯硅烷的化学浴沉积效果;亲水改性的最佳工艺条件为:NaOH的浓度为40%、反应时间为60 min、反应温度为70℃;化学沉积后的.PVDF/13MMA共混膜接触角高达154.6°;集灰实验表明,倾斜角度约为1°时水滴能将膜表面的灰尘带走,膜的防污自洁性能优良。     

聚偏氟乙烯/聚离子液体共混膜的优化制备

研究制备了由聚离子液体(PIL)改性的聚偏氟乙烯(PVDF)共混膜,探讨了凝固浴组成的变化对PVDF共混膜的影响。通过FTIR、XPS、SEM分析了膜表面的组成及膜孔结构;通过水接触角和机械强度测试分析了膜的性能,并研究了膜对橙黄Ⅳ的吸附容量。实验表明:随着凝固浴中DMF含量的增加,膜的水接触角从77.79°减小到51.94°,亲水性显著增强,膜对橙黄Ⅳ的吸附容量从7.7 mg/g增加到16.1 mg/g,实现对PVDF膜的优化改性。     

膜蒸馏用PVDF抗复合污染膜的制备与测试

为提高膜的抗污染能力,对聚偏氟乙烯（PVDF）平板膜进行表面涂覆改性,得到超疏水PVDF平板膜,再将超疏水PVDF平板膜进行表面亲水化改性,制备出超疏水/亲水复合PVDF膜。当PVDF的质量浓度为2%、聚乙二醇（PG）的质量浓度为39%、涂敷液温度为50℃、蒸发时间为10 s、凝固浴温度为60℃时,超疏水PVDF平板膜接触角达到154.8°。表面亲水改性制得的PVDF超疏水/亲水复合膜的接触角为41°。然后研究了超疏水PVDF平板膜和PVDF超疏水/亲水复合膜的抗膜污染性能。结果显示,超疏水PVDF平板膜具有优良的抗无机污染性能和一定的抗有机污染性能;PVDF超疏水/亲水复合膜不仅具有优良的抗无机污染性能,而且其抗复合污染性能尤其是抗有机污染性能得到明显提升,为进一步构建高性能膜蒸馏抗污染膜提出了一个可行的技术方向。     

聚偏氟乙烯共混膜的制备和性能研究

主要讨论了聚偏氟乙烯(PVDF)膜以及聚甲基丙烯酸甲酯(PVDF/PMMA)、PVDF/PMMA/PS(聚砜)共混膜的制备及性能,并研究了不同添加剂对PVDF/PMMA/PS共混膜的结构和性能的影响。实验数据表明:PVDF/PMMA/PS共混膜的通量最大;PVPK 40成膜通量最大;T iO 2成膜截留率最大。     

聚偏氟乙烯中空纤维膜的制备

本丈研究了聚偏氟乙烯（PVDF）中空纤维微滤膜的制备。采用亲水聚合物材料（如PMMA、改性聚醚硅油等）对聚偏氟乙烯材料进行共混改性,显著提高了膜材料的亲水性;同时由于材料性质的改变,导致膜材料在成膜时的凝胶特性和相转化发生变化,所成膜的孔径、通水量、孔隙率、表面性能等也发生改变。通过选择合适的共混体系,可制备出高性能、高孔隙率、表面亲水的聚偏氟乙烯中空纤维膜。     

聚偏氟乙烯膜亲水化改性研究进展

为弥补强疏水性聚偏氟乙烯(PVDF)膜在实际应用中的缺陷,从膜本体及膜表面2个角度入手,阐述了国内外对PVDF膜亲水化改性的主要方法。膜本体改性主要是将膜材料与亲水性聚合物或无机纳米材料共混,从而改善PVDF膜的亲水性能;而膜表面改性则主要是通过表面涂覆改性与表面接枝改性来实现。PVDF膜亲水性的增强,能有效改善膜的抗污染能力,从而大大提高膜的过水通量,并延长其使用寿命。     

PVDF膜的亲水改性及其研究进展

聚偏氟乙烯(PVDF)具有优异的力学性能和化学性能,是制备水处理膜的理想材料。然而,PVDF膜表面疏水性极强,在水处理过程中容易受到杂质的污染,因此,对PVDF膜进行亲水改性具有重要意义。本研究主要从表面涂覆改性、表面接枝改性和共混改性等3个方面综述国内外研究者近年来对PVDF膜亲水改性的研究成果,总结各种改性方法的优缺点,并对未来发展趋势进行展望。     

凝固浴组成对PVDF/PVDF-g-PAA共混膜结构与性能的影响

为了进一步提高PVDF膜的亲水性及渗透性能,本文通过在膜内引入聚偏氟乙烯接枝聚丙烯酸(PVDF-g-PAA),提高共混膜的亲水性,并在凝固浴中加入N, N-二甲基乙酰胺(DMAc),改善聚偏氟乙烯/聚偏氟乙烯接枝聚丙烯酸(PVDF/PVDF-g-PAA)共混膜的结构与性能。利用浊点法对PVDF/PVDF-g-PAA共混膜的成膜热力学进行了研究,相比于水/乙醇凝固浴,水/DMAc凝固浴的使用会抑制PVDF/PVDF-g-PAA的相分离速度,体系变得更加稳定。采用傅里叶红红外光谱仪(FT-IR)和X-射线光电子能谱仪(XPS)表征聚合物及膜的化学结构,并通过原子力显微镜和扫描电镜观察膜的表断面结构。结果表明,随着凝固浴中DMAc含量的增加,膜的致密皮层逐渐变薄,膜断面中的指状孔结构逐渐向海绵状结构转变,膜表面变粗糙,平均孔径增加,共混膜纯水通量变大。当DMAc含量为50%时,膜的纯水通量最高,可达(1 084±74)L/(m~2·h),同时具备较高的断裂强度(2.6±0.1)MPa。     

PVDF膜的亲水改性及其抗污染性能的研究新进展

PVDF膜由于其较强的疏水性能,在水处理应用中需要较强的驱动力,使得运行费用增加;同时膜的疏水性也会导致膜污染、膜堵塞,从而造成膜水通量的降低。因此,针对此问题,提出了PVDF膜的改性,通过对PVDF膜进行改性来提高它的亲水性能从而改善膜的性能。介绍了近年来PVDF膜亲水改性的研究新进展,PVDF膜的改性主要有表面改性和共混改性,表面改性主要有表面接枝与表面涂覆,共混改性主要的共混物质有亲水聚合物、无机纳米粒子以及碳基纳米材料等。研究发现,通过改性后的PVDF膜亲水性能、抗污染性能以及膜的机械性能都有所提高。这为解决PVDF膜的污染问题提供了一种实际可行的方法,并通过提高其亲水性而降低了运行成本。     

相转化法制备PVDF超滤膜及其亲水化改性研究进展

综述了聚偏氟乙烯(PVDF)超滤(UF)膜在相转化制备方法和亲水化改性两方面的最新研究进展。在相转化制备方法中,介绍了聚合物用量、溶剂的选择、添加剂的种类和用量及凝固浴组成和温度对膜结构和性能的影响;在PVDF超滤膜亲水化改性方面,介绍了共混改性、共聚改性、辐照接枝改性、等子体改性等方法的机理、特点和近年来的研究进展,指出了共混改性是今后亲水改性的主要方向。     

紫外接枝丙烯酸对PVDF膜表面改性的研究

以二苯甲酮为光引发剂,通过紫外辐照将亲水性单体丙烯酸接枝于聚偏氟乙烯(PVDF)膜的表面。考察了光引发剂浓度和辐照时间对接枝率的影响,并利用衰减全反射光谱和扫描电子显微镜对接枝后PVDF膜表面的化学组成和微观形貌进行了表征。结果表明:随着光引发剂浓度的增大,丙烯酸的接枝率先增大后减小。通过纯水接触角和吸水率研究了接枝后的PVDF膜的亲水性,发现接枝后的PVDF膜的亲水性得到明显改善。     

Hydrophilic Modification of PVDF Microfiltration Membrane with Poly (Ethylene Glycol) Dimethacrylate through Surface Polymerization

The hydrophilic modification of poly (vinylidene fluoride) (PVDF) membrane with poly (ethylene glycol) dimethacrylate (PEGDMA) through grafting reaction for antifouling was reported. The influence of PEGDMA content, reaction temperature and time, on the structure, morphology, antifouling, and hydrophilicity of PVDF-g-PEGDMA membrane has been investigated. The PEGDMA monomers that were grafted on the surface of PVDF microfiltration membrane were confirmed by Attenuation total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), and morphology study conducted by SEM revealed the changes before and after modification. The protein adsorption, filtration performance, water content, and dynamic contact angle were used to characterize the antifouling and hydrophilicity of the modified PVDF membranes. Compared with the pristine PVDF membrane, the bovine serum albumin (BSA) adsorption on the PVDF-g-PEGDMA membrane decreased about 80%, and the water contact angle of the membrane dropped to 0°. Besides, the experimental results revealed no significant differences between the membrane samples with respect to pore size.     

Surface modification of PVDF hollow fiber membrane to enhance hydrophobicity using organosilanes

This work investigates the membrane modification to enhance hydrophobicity aiming for applications as membrane contactors. The PVDF membranes were activated by NaOH and by plasma activation followed by grafting using three organosilanes. For the NaOH, the contact angle of original membranes (68°) was decreased from 44° to 31° with increasing NaOH concentration from 2.5M to 7.5M at 60°C for 3 h. The contact angle of NaOH treated membranes was increased to 100° after modification with 0.01M FAS‐C8 for 24 h. A needle‐like structure was observed on the membrane surface while there was no significant change in pore size and pore size distribution. Moreover, FTIR and XPS data showed Si peak and composition. The mechanical strength was improved. The surface modified membranes under helium plasma activation followed by grafting with 0.01M FAS‐C8 for 24 h showed higher contact angle, mechanical strength and surface roughness than that obtained by NaOH activation method while other physical properties did not change. The long‐term performance test for 15 days of operation was conducted. The modified membranes exhibited good stability and durability for CO₂ absorption. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Enhanced modification technique for polyacrylonitrile UF membranes by direct hydrolysis in the immersion bath

Conventional hydrolysis modification of polyacrylonitrile (PAN) membranes is usually carried out in a post-treatment step during which hydrophilic groups are created on the membrane surface. In this article, however, direct hydrolysis in the immersion bath is proposed as a new and simple approach for simultaneous membrane preparation and modification. The main advantages of this method include lower alkali concentrations, promptness, and the lack of need for elevating temperature compared to other studies. The cast films were immersed in the coagulation bath containing aqueous NaOH solutions of various concentrations (0.003, 0.0125, 0.025, 0.05, and 0.1 M) for 1, 3, 5, and 10 min, which were then transferred to a bath of pure water. Membranes were characterized by pure water flux, porosity, average pore diameter, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, mechanical properties, rejection, and flux recovery ratio (FRR) measurements. At all treatment times, the pure water flux of modified membranes reached its maximum at low NaOH concentrations with a substantial increase (210%) in the membrane treated with 0.0125 M NaOH for 1 min. Furthermore, the kinetics of the hydrolysis reaction was considered to provide deeper insights into morphological changes occurring during the hydrolysis. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48583.     

凝固浴组成和温度对PVDF疏水微孔膜结构与性能的影响

利用非溶剂相转化法(NIPS),以聚偏氟乙烯(PVDF)/磷酸三乙酯(TEP)-N,N-二甲基乙酰胺(DMAc)为铸膜液体系,乙醇水溶液为凝固浴制备高性能的PVDF疏水微孔膜。考察了凝固浴中乙醇(EtOH)含量及凝固浴温度对PVDF成膜分相速率、膜结构和膜疏水性的影响。实验结果表明,在20℃的凝固浴温度下,凝固浴中乙醇含量的升高减慢了铸膜液体系的分相速率,提高了PVDF膜的孔隙率;在凝固浴中添加60%(wt)的乙醇,可形成表面荷叶状结构和截面对称的海绵状结构,膜表面的接触角为130.3°,呈很强的疏水性,并具有较优的膜强度。     

Performance Evaluation of Alkaline Treated Poly(vinylidene fluoride) Membranes

A poly(vinylidene fluoride) (PVDF) hollow fiber membrane surface was modified by alkaline treatment in this study. This subject was selected with the aim to confirm the mechanisms of alkaline degradation of PVDF membranes, characterize the variations of membrane surface morphology (e.g., average pore size, pore size distribution, porosity, etc.), and estimate the membrane fouling potential by a bench-scale test with synthetic surface water. The conditions of the alkaline treatment covered various concentrations, temperature, and processing time. The results of this study indicate that the hydrophilic PVDF membranes can be obtained after appropriate treatment without loss of integrity of the membrane surface. All factors, including the concentration of NaOH, temperature, and processing time affect membrane properties. The surface images and air flow rate of unmodified and modified membranes showed difference in their average pore size and pore size distribution. In general, the increase of the processing time decreases the average pore size at constant concentration and temperature; the increase of the NaOH concentration in solution and temperature fastens the degradation process. Membrane pure water flux decreased after alkaline treatment. This can be attributed to the decrease of pore size. However, the membrane anti-fouling potential increased after alkaline treatment due to the enhancement of hydrophilic property of membrane surface.