基于响应面分析法的PVDF膜紫外接枝亲水改性的研究

采用非溶剂致相分离法制备了聚偏氟乙烯(PVDF)分离膜;以二苯甲酮为光引发剂,通过紫外接枝将亲水性单体丙烯酸(AA)和甲基丙烯酸-2-羟基乙酯(HEMA)接枝在PVDF膜表面。应用响应面分析法设计了紫外接枝实验,分别考察了单体浓度和紫外辐照时间对两种PVDF膜亲水改性效果的影响,优选出最佳工艺方案。AA接枝PVDF膜的最优方案:w(AA)为1.98%,辐照时间为40min,此时接枝膜的吸水率为109.95%。HEMA接枝PVDF膜的最优方案:w(HEMA)为1.5%,辐照时间为36.64min,接枝膜的吸水率为96.95%。     

辐射接枝改性聚酯薄膜表面防雾滴性研究

采用γ射线辐照引发接枝的方法,在聚酯(PET)膜表面接枝丙烯酸、丙烯酰胺、丙烯酸羟乙酯,获得具有表面亲水性的聚酯膜。并研究了不同辐照强度、辐照时间、温度、单体浓度下的接枝规律。结果表明,随着接枝率的上升,PET膜对水接触角逐渐降低,达到一定值后变化不大。     

紫外辐照接枝甲基丙烯酸对无纺布性能影响的研究

以二苯甲酮作为光引发剂,利用紫外辐照法引发单体接枝聚合反应,将亲水性单体甲基丙烯酸接枝在无纺布表面对其进行改性。通过测定接枝率,评价聚合物在无纺布表面的接枝程度;通过测定未改性及改性无纺布的膜通量,考察了改性无纺布表面的透水性;通过ATR-FTIR红外光谱和扫描电镜(SEM)对改性前后无纺布进行结构表征。实验结果表明:单体体积分数20%,辐照距离20cm,辐照时间40min,光引发剂二苯甲酮浓度0.1mol/L时,接枝率和膜通量达到最大值,分别为20%和1387L/m2·h。ATR-FTIR红外光谱分析表明无纺布表面负载了亲水性-COOH。     

PVC片材表面的光接枝亲水化处理

采用光接枝聚合方法对商品化PVC片材进行了表面亲水化处理。以二苯甲酮作引发剂 ,丙烯酸为接枝单体研究了反应过程中单体浓度、引发剂浓度、反应时间对亲水化效果的影响。衰减全反射红外光谱 (ATR FTIR)分析发现 ,在 15 5 5cm-1处出现COO-的特征峰 ,证明丙烯酸已经接枝到材料表面。随着反应时间的延长 ,接触角持续下降 ,3 0s以后趋于恒定 ,最低可达 3 3°。较低单体浓度下 ,均聚反应较弱 ,材料的亲水性要好于高单体浓度时的情况。同样 ,较低引发剂浓度时 ,引发剂的自屏蔽效应弱 ,有利于接枝反应 ,接触角要比高引发剂浓度条件下小     

丙烯酸接枝PVDF超滤膜亲水改性研究

采用自由基聚合方法将丙烯酸接枝到经过消去反应形成一定C=C含量的PVDF中空纤维超滤膜表面,改善了膜表面的亲水性。依据超滤膜的孔径结构要求,调控丙烯酸接枝链的长度。通过XPS、SEM和水通量实验分析效果表明,丙烯酸接枝改性PVDF中空纤维超滤膜表面引入了-COOH和-OH亲水基团,膜表面和孔壁形成的亲水层没有改变膜表面的孔径尺寸,水通量比改性前提高了280%以上。     

丙烯酸接枝聚酰胺/聚醚酰亚胺复合纳滤膜的制备

为了提高复合纳滤膜的抗污染性能,采用紫外光照接枝法将丙烯酸接枝到聚酰胺/聚醚酰亚胺(PA/PEI)复合纳滤膜的皮层上,通过引入羧基基团来增加膜表面的亲水性。考察了丙烯酸单体质量分数、辐照时间对表面接枝率和膜分离性能的影响,并对优选的膜进行了抗污染性能测试。结果表明:丙烯酸质量分数与紫外辐照时间对膜分离性能的影响规律相同,膜通量随质量分数的增加与辐照时间的延长呈现先增加后减小的趋势,而截留率则保持基本不变,当丙烯酸质量分数2%,辐照时间2 min时,膜的通量达到13.12 L/(m2·h),较接枝前的11.94 L/(m2·h)略高;在含有1 g/L牛血清蛋白(BSA)的溶液中,接枝后的膜通量下降明显低于接枝前的膜。研究表明丙烯酸接枝可以有效改善膜表面亲水性,从而有利于提高膜的抗污染性能。     

线形低密度聚乙烯粉料固相光接枝丙烯酸的研究

采用接枝率测定、红外光谱、光电子能谱、接触角、剥离强度等测试，研究了紫外线（UV）引发丙烯酸（AA）固相表面接枝线形低密度聚乙烯（PBLLD）粉料的影响因素（温度、单体浓度和反应时间），接枝PE—LLD表面结构、微观形态和性能。结果表明：UV能高效地引发AA在PE-LLD材料表面接枝聚合，随辐照时间延长、温度升高和单体浓度增大，接枝率增大，在实验条件下达到满足实际应用所需接枝率（约0．5％质量含量）的反应时问可达分钟数量级。接枝改性后，PE-LLD与水的接触角下降，亲水性增强；对钢材和聚乙烯黏接强度提高。     

辐照接枝丙烯酸改性聚砜超滤膜

采用液相共辐照技术在聚砜超滤膜上接枝丙烯膜，通过改变辐照剂量和丙烯酸单体浓度可以获得具有不同接枝率的改性聚砜膜。实验结果表明，随着接枝率的提高，改性聚砜抗蛋白质吸附污染的能力显著增强，并且认为接枝膜的亲水性提高是膜污染减轻的主要原因。     

聚酯膜光接枝丙烯酸表面改性无钯化学镀铜

研究了聚酯膜光接枝丙烯酸表面改性化学镀铜。对比气相法光接枝和液相法光接枝,结果表明,使用气相法时丙烯酸可重复利用;使用表面全反射傅立叶变换红外光谱对聚酯膜进行了表征;通过接枝丙烯酸引入羧基,与银离子进行离子交换,能实现无钯活化引发化学镀铜,通过扫描电镜对化学镀铜层表面形貌进行观察。     

血液过滤用熔喷PBT非织造布紫外辐照接枝改性研究

研究了血液过滤用熔喷PBT非织造布的紫外辐照气相接枝改性方法。通过实验选择了丙烯酸(AAc)为接枝单体 ,探讨光照时间、预辐照时间、单体温度、引发剂浓度、氮气压力对接枝率和表面润湿张力的影响 ,结果得到最佳的紫外辐照接枝条件为 :室温下 ,光距 2 0cm ,预浸 10min ,二苯甲酮 (BP) 0 .0 37mol/L ,冲入单体的氮气流量 87.5h/L ,反应时间 30min。PBT非织造布AAc紫外辐照接枝后表面润湿张力可以达到 85mN/m左右 ,且表面润湿张力随接枝率的提高而增加     

Tailoring bulk and surface grafting of poly(acrylic acid) in electron-irradiated PVDF

Endowing conventional hydrophobic poly(vinylidene fluoride) (PVDF) films with hydrophilic properties was conducted using electron beam irradiation. Grafting of acrylic acid (AA) in/onto pre-irradiated PVDF films was investigated. Reaction parameters, monomer concentration and inhibitor concentration were examined. Radiation grafted films (PVDF-g-PAA) were synthesized with various grafting yields ranging from 12 to 130 wt % in presence of Mohr's salt (25 wt %). Below 80 wt % of monomer concentration, the degree of swelling was found to increase with the grafting yield. The PAA was arranged randomly in all PVDF matrix (grafting through). Above 80 wt % of monomer concentration, the PAA was grafted only onto the surface of PVDF films leading to a highly dense layer of PAA. Grafting through or surface grafting processes were achieved by varying the water fraction in the initial monomer solution. Water molecule acts not only as a carrier for the monomer but also as a plasticizer expanding the film in the three dimensions. Evidences of grafting through and surface grafting were produced using FTIR in ATR mode, SEM coupled to X-ray detection and XPS. An accurate quantification of AA units was possible up to the micromole via a Cu²⁺–EDTA complex analyzed by UV–vis spectroscopy.     

Antifouling enhancement of PVDF membrane tethered with polyampholyte hydrogel layers

The preparation and property of antifouling poly(vinylidene fluoride) (PVDF) membrane tethered with polyampholyte hydrogel layers were described in this work. In fabricating these membranes, the [2‐(methacryloyloxy)ethyl] trimethylammonium chloride and 2‐acrylamide‐2‐methyl propane sulfonic acid monomers were grafted onto the alkali‐treated PVDF membrane to yield polyampholyte hydrogel layers via radical copolymerization with N,N′‐methylenebisacrylamide as crosslinking agent. The analyses of fourier transform infrared attenuated total reflection spectroscopy and X‐ray photoelectron spectroscopy confirm the covalent immobilization of polyampholyte hydrogel layer on PVDF membrane surface. The grafting density of polyampholyte hydrogel layer increases with the crosslinking agent growing. Especially for the membrane with a high grafting density, a hydrogel layer can be observed obviously, which results in the complete coverage of membrane pores. Because of the hydrophilic characteristic of grafted layer, the modified membranes show much lower protein adsorption than pristine PVDF membrane. Cycle filtration tests indicate that both the reversible and irreversible membrane fouling is alleviated after the incorporation of polyampholyte hydrogel layer into the PVDF membrane. This work provides an effective pathway of covalently tethering hydrogel onto the hydrophobic membrane surface to achieve fouling resistance. POLYM. ENG. SCI., 55:1367–1373, 2015. © 2015 Society of Plastics Engineers     

Stability of acrylic acid grafted poly(vinylidene fluoride) hollow fiber membrane prepared by high‐energy electron beam

In this article, poly(vinylidene fluoride) (PVDF) hollow fiber membrane and acrylic acid (AA) were co‐irradiated by high‐energy electron beam to introduce hydrophilic carboxylic groups on the membrane surface. Thermal capability, mechanical performance, pore size, and permeation property were investigated to determine the stability of the membrane pore structure before and after irradiation polymerization. The decomposition temperature, melting point, glass transition temperature, and breaking force of the PVDF‐g‐AA membrane increased slightly because of irradiation grafting polymerization. After 15 months of storage, the pore size distribution of the PVDF‐g‐AA membrane became smaller and more dispersive. The pure water flux and the rejection to bovine serum albumin of the PVDF‐g‐AA membrane increased significantly with the increase in hydrophilicity and decrease in pore size. The results indicated that the structure and properties of the PVDF hollow fiber membrane were stable after high‐energy electron beam irradiation grafting polymerization, even after 15 months of storage. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41165.     

Controlled grafting from poly(vinylidene fluoride) microfiltration membranes via reverse atom transfer radical polymerization and antifouling properties

A reverse atom transfer radical polymerization (RATRP) with benzoyl peroxide (BPO)/CuCl/2,2-bipyridine (Bpy) was applied onto grafting of poly(methyl methacrylate) (PMMA) and poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) from poly(vinylidene fluoride) (PVDF) microfiltration (MF) membrane surfaces, including the pore surfaces. The introduction of peroxide and hydroperoxide groups onto the PVDF membranes was achieved by ultraviolet (UV) irradiation in nitrogen, followed by air exposure. RATRP from UV pretreated hydrophobic PVDF membranes was then performed for attaching well-defined homopolymer. The chemical composition of the modified PVDF membrane surfaces was characterized by attenuated total reflectance (ATR) FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The surface and cross-section morphology of membranes were studied by scanning electron microscopy (SEM). The pore sizes of the pristine PVDF and the PMMA grafted PVDF membranes were measured using micro-image analysis and process software. With increase of graft concentration, the pore size of the modified membranes decreased and became uniform. Kinetic studies of homogeneous (in toluene solution) system revealed a linear increase in molecular weight with the reaction time and narrow molecular weight distribution, indicating that the chain growth from the membrane surface was a “controlled” or “living” grafting process. The introduction of the well-defined PMMA on the PVDF membrane gave rise to hydrophilicity. Protein adsorption and protein solution permeation experiments revealed that the UV pretreated hydrophobic PVDF membrane subjected to surface-initiated RATRP of methyl methacrylate (MMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) exhibited good antifouling property.     

Functionalizing of polyurethane surfaces by photografting with hydrophilic monomers

Poly(ester urethane) (PU) with functional groups (amide, hydroxyl, carboxyl) on surfaces were prepared by grafting monomers such as acrylamide (AAm), hydroxyethyl acrylate (HEA), and methacrylic acid (MAA) onto the PU membranes. Grafting copolymerization was carried out by the combined use of photooxidization and UV irradiation grafting. The PU membrane was photooxidized in hydrogen peroxide solution under UV light to yield hydroperoxide groups on the surface and then irradiation grafting with monomer in water. The ATR‐FTIR spectrum, X‐ray photoelectron spectroscopy characterized the grafted copolymers and verified the occurrence of grafting copolymerization. The results showed that the content of hydroperoxide groups yielded was dependent on the photooxidization time and reached maximum at about 8 h. Grafting copolymerization was enhanced when irradiating by UV light. The degree of grafting was increased with the increase of content of hydroperoxide groups, irradiation time, and monomer concentration. The grafting copolymerization was enhanced when an appropriate amount of ferrous ions was added. After grafting, the wettability of PU and the water absorption percentage increased with the degree of grafting. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2505–2512, 2000     

Preparation and modification of nano-porous polyimide (PI) membranes by UV photo-grafting process: Ultrafiltration and nanofiltration performance

Polyimide (PI) membranes were prepared via non-solvent induced phase separation. The prepared PI membranes were modified by ultraviolet light (UV) and graft polymerization of hydrophilic acrylic and amino monomers in the absence and presence of benzophenone (BP) onto the membrane surface to introduce more hydrophilic and lower fouling membranes. Acrylic acid (AA) and 2-hydroxyethylmethacrylate (HEMA) as acrylic monomers, 1,3-phenylenediamine (mPDA) as amino monomer and BP as photo-initiator were used. The unmodified and modified PI membranes were characterized by degree of grafting (DG) and contact angle measurements. They were also characterized by their ultrafiltration performance with pure water and non-skim milk and nanofiltration performance with 500 ppm NaCl and MgSO₄ single solutions. The DG was increased with increasing monomer concentration, especially at presence of BP. The contact angle measurements indicated that hydrophilicity of PI membrane was improved after UV photografting of hydrophilic monomers onto the membrane surface in all cases. The ultrafiltration results showed that the pure water fluxes and milk water permeation of PI membrane declined after monomer photo-grafting while the protein rejection was extremely increased. The decrease in permeability was remarkable in the presence of BP. The mean pore size of base and modified PI membranes ranged from 8.3 to 0.55 nm when calculated from the solute transport data. Moreover, the irreversible flux loss and flux recovery of PI membrane were modified by UV photo-grafting of hydrophilic monomers. All modified membranes showed considerable NaCl and MgSO₄ rejections. In addition, the membrane modified with mPDA at presence of BP showed highest NaCl and MgSO₄ rejections.     

微乳液法腈纶接枝聚苯胺及其性能研究

采用低温等离子体技术对腈纶纤维表面进行处理,使用苯胺微乳液在腈纶表面进行接枝聚合,对腈纶进行改性处理,通过增重率、导电率测试、接枝聚合的因素和接枝聚合对腈纶纤维结构、导电性能和强力进行分析评价;扫描电镜和红外测试显示聚苯胺成功接枝上腈纶表面;腈纶接枝聚苯胺后,导电性能增加,强力变化不大,但伸长率略有降低。     

Protein immobilization onto poly (vinylidene fluoride) microporous membranes activated by the atmospheric pressure low temperature plasma

Hydrophobic poly (vinylidene fluoride) (PVDF) membrane surface was treated with atmospheric pressure low temperature plasma and investigated physical and chemical surface characterization. The contact angle of water on the exposed membrane surface was reduced with increasing of the treatment voltage and time, so indicates that the treatments can modify the PVDF membrane surface from hydrophobic to hydrophilic. In order to analyze the phenomenon in detail, the progress of defluorination including dehydrofluorination and oxidation reactions onto the surface was examined by X-ray photoelectron spectroscopy (XPS), and revealed the most effective treatment condition. The degree of grafting used acrylic acid monomer onto the surface has influenced with monomer concentration, reaction temperature and reaction time. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology. The membrane surfaces conjugated bovine serum albumin (BSA) as a protein were surely detected the nitrogen element contained with BSA.     

Surface modification of polypropylene microporous membrane by grafting acrylic acid using physisorbed initiators method

Surface modification of microporous polypropylene (PP) membrane was performed by graft polymerization of acrylic acid using physisorbed initiators method. The factors effecting on the grafting degree such as monomer concentration, reaction temperature and initiator density were determined. The morphological and microstructure changes of the membrane were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). The pure water contact angle, protein adsorbed amount, water flux, and antifouling property of the grafted membrane were investigated. The results indicated that the pore size and porosity of the grafted membrane were reduced and the static contact angle of pure water on the grafted membrane decreased from 108° to 40° with the increase of grafting degree. The amount of protein adsorbed on the grafted membrane decreased about 30% compared to the virgin polypropylene membrane when the grafting degree was 18.71%. Though the water flux reduced, the flux recovery of the grafted membrane increased 82.66% with the grafting degree 16.0%. The hydrophilic and antifouling property of the grafted membrane also were improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

多孔膜基材对等离子体接枝膜微观结构的影响

采用等离子体诱导接枝聚合法,在有机聚偏氟乙烯(PVDF)膜、尼龙(N6)膜和无机多孔阳极氧化铝(PAA)膜上接枝甲基丙烯酸(MAA),系统地研究了多孔膜基材及接枝工艺条件对接枝开关膜微观结构的影响。结果发现,对于PVDF基材膜,单体溶液脱气次数越多接枝率越大。对于不同类别的多孔膜基材,采用相同工艺条件接枝时,N6膜的接枝率高于PVDF膜,PAA膜接枝率最低。在接枝率相近的时候,接枝层在PVDF膜整个断面孔内和表面均存在,而N6膜则主要集中在表层。在PAA膜上接枝时发现,等离子体照射功率的强弱对基材膜的影响很大,当功率超过50W时,PAA膜表层就会被刻蚀而导致膜的质量减轻。