PVDF亲水复合膜的制备及表征

聚偏氟乙烯(PVDF)膜材料存在强疏水性的缺陷,亲水化改性是解决该问题的主要途径。以PVDF为基膜材料、聚乙烯醇(PVA)为共混材料、N,N-二甲基乙酰胺(DMAc)为溶剂,采用相转化法制备PVDF/PVA复合膜。考察了复合膜的PVDF/PVA共混比、固含量、低分子化合物添加剂、聚合物添加剂等非溶剂添加剂对复合膜接触角的影响。结果表明,当PVDF/PVA共混比为7/3,固含量为13%时,制备的复合膜接触角为22.92°;当添加剂为无水氯化锂、纳米二氧化硅、聚乙烯吡咯烷酮(PVP)时,复合膜接触角分别从53.12°、30.51°和41.89°都降低到了0°,亲水性提高,其中纳米二氧化硅作为添加剂时复合膜亲水性最好;当添加剂为丙三醇、PMMA、PEG时,复合膜接触角都增大,亲水性变差。     

N-乙烯基咪唑共聚交联微球的制备及其对二氯苯酚的吸附特性

采用悬浮聚合法,以N-乙烯基咪唑(NVI)为主单体、苯乙烯(St)为共单体、乙二醇二甲基丙烯酸酯(EGDMA)为交联剂、聚乙烯醇(PVA)为分散剂,制备了吸附材料PNVI-St交联微球。重点考察了分散剂用量、搅拌速率、油水两相体积比、交联剂用量、NaCl用量对交联微球的成球性能及粒度的影响规律,研究了该微球对二氯苯酚的静态吸附性能。结果表明:分散剂用量、搅拌速率与油水两相体积比是影响交联微球制备的主要因素,在水相中加入电解质NaCl有助于成球过程,控制悬浮聚合的反应条件,可以制备出球形度好、粒径在100~200μm可调控的交联微球PNVI-St。静态吸附实验结果表明:凭借强烈的氢键相互作用,微球表面的咪唑基团对二氯苯酚具有很强的吸附能力,饱和吸附量可达143 mg/g。     

环氧改性水性聚氨酯乳液的制备及其膜性能

以聚己内酯二元醇(CAPA)为软段,异佛尔酮二异氰酸酯(IPDI)和六亚甲基二异氰酸酯(HDI)为硬段,环氧树脂E-44为大分子交联剂,经相转化法合成了一系列环氧树脂改性负离子水性聚氨酯(EPPU)自乳化乳液,并制备了改性水性聚氨酯的固化膜.通过FTIR、TGA及接触角、力学性能测试对聚合物结构及其膜性能进行了研究.通过原子力显微镜(AFM)观察膜表面形态和表面粗糙度.乳液粒径及粒径分布通过动态激光光散射法(DLLS)测定.FTIR分析表明环氧树脂的羟基和环氧基都参与了发应.TGA表明,环氧树脂的加入可以提高聚氨酯的热稳定性.随着w(E-44)增大,改性聚氨酯膜的拉伸强度得到改善,断裂伸长率减小.随着w(E-44)增大,乳液粒径增大,薄膜的接触角增大,改性后的PU膜表面光滑度下降,拒水性增强.     

尿素/乙醇胺复配增塑聚乙烯醇性能的研究

采用尿素/乙醇胺为复合增塑剂,利用流延法制备了增塑改性的PVA膜.通过FTIR法研究了尿素/乙醇胺复合体系与PVA的相互作用,采用XRD、DSC考察了增塑改性PVA膜的结晶性能和热性能.研究结果表明,乙醇胺作为尿素的良溶剂,能有效抑制尿素从PVA基体中析出.由尿素、乙醇胺组成的复合增塑剂能破坏PVA分子中的氢键作用、降低PVA的结晶度和熔点,对PVA的增塑作用显著.增塑改性后的PVA膜在水中的溶胀率(DS)下降,溶失率(S)增加.力学性能测试表明增塑改性后的PVA膜拉伸强度(TS)降低,断裂伸长率(E%)提高.含30phr尿素/乙醇胺的PVA膜的拉伸强度、断裂伸长率分别为23.89MPa和542.88%.     

聚乙烯醇/丙烯酸共聚物水凝胶的制备及溶胀性

制备了具有pH敏感性的聚乙烯醇(PVA)/丙烯酸(AA)共聚物水凝胶,研究了PVA与AA之间配比、交联剂、引发剂用量对凝胶转化率的影响,对水凝胶的溶胀行为和pH敏感性也进行了详细研究.实验表明PVA与AA的质量比为(1∶9)~(3∶7)之间时,引发剂和交联剂分别为PVA和AA总量的0.2%和0.3%时,凝胶转化率高.随着水溶液pH值从3增加到9,凝胶的溶胀比也相应的增加,表现出明显的pH敏感性.     

羧甲基纤维素钠/聚(N-异丙基丙烯酰胺)纳米复合水凝胶的制备及结构性能表征

以无机粘土为交联剂制备了具有温度、pH双重敏感特性的羧甲基纤维素钠/聚(N-异丙基丙烯酰胺)/粘土半互穿网络纳米复合水凝胶(CMC/PNIPA/Clay semi-IPN),并通过红外和透射电镜对其结构和形态进行了表征。在酸性(pH=1.2)和20℃条件下,分别研究了温度和不同pH缓冲液对该凝胶溶胀度的影响,测定了复合水凝胶的力学性能。结果表明:水凝胶中的粘土被剥离成单片层,且均匀分散在凝胶网络中,起交联剂的作用,而CMC以线性大分子的形态存在;CMC/PNIPA/Clay具有良好的温度、pH双重敏感特性;凝胶的断裂伸长率>1 000%。     

竹纤维复合亲水膜的制备及性能研究

以碱处理的改性竹纤维(BF)、乳酸(LA)为反应原料,制备PLA-g-BF接枝物。PLA-g-BF接枝物分别与壳聚糖(CS)、聚乙烯醇(PVA)为原料的体系进行复合,制备竹纤维复合亲水膜,探究了CS(PVA)溶液质量浓度和PLA-g-BF/CS(PVA)溶液质量配比对所制备的竹纤维复合亲水膜的结构、拉伸强度、形貌、亲水性、附着力及降解性的影响。结果表明:CS溶液质量浓度为1/40(g/mL),接枝物与CS溶液质量配比为2∶40时,膜的拉伸强度为4.93MPa,接触角为72.9°,硬度为2H,基本不降解;PVA溶液质量分数为7%,接枝物与PVA溶液质量配比为2∶40时,膜的拉伸强度为17.2MPa,接触角为53.2°,硬度为5H,6天内全部降解。     

PU/PNIPAM semi-IPN微孔膜温度响应性研究

将聚氨酯(PU)与聚N-异丙基丙烯酰胺(PNIPAM)半互穿网络聚合物(semi-IPN)通过浸入沉淀相转化方法制备成微孔膜,并从亲水性、吸水溶胀性以及透湿性等方面对其温度响应性进行了讨论.PNIPAM的引入使膜的亲水性、吸水性和透湿性大为改善,并显著提高了膜的温度响应能力;但与此同时也使得膜的韧性降低.当PU/PNIPAM为3/1时,可获得最好的综合性能.同传统无孔致密膜相比,PU/PNIPAM semi-IPN微孔膜的透湿机理是基于微孔的开闭,在维持显著的温敏透湿性的同时可实现较高的高温透湿量.     

HA在PVA/CMC共混膜上的交互沉积及其表征

用溶液浇铸法制备聚乙烯醇/羧甲纤维素钠(PVA/CMC)共混膜,在对其进行交联改性的基础上,通过交互沉积法在膜表面沉积羟基磷灰石(HA),以制备PVA/CMC/HA复合材料。通过SEM、FT-IR、XRD等对其进行表征,探索PVA与CMC共混比例及交互周期对HA矿化速率的影响。结果表明,经过交联后的薄膜,在醇水混合溶液中能够稳定存在,其表面生成的HA含量随着交互周期和CMC含量的增加有明显增加,这种共混薄膜材料有望成为软骨修复材料的有效基体。     

电纺聚乙烯醇超细纤维膜的性能研究

由电纺制备聚乙烯醇(PVA)超细纤维膜,以扫描电镜观察纤维的微观形貌,用X射线衍射研究超细纤维膜的结晶行为,并测定了PVA超细纤维膜的力学性能和吸水性.结果表明,PVA超细纤维的平均直径为(184±26)nm,超细纤维中PVA的结晶度和晶体有序程度较浇铸膜低.超细纤维膜的拉伸强度、模量和断裂伸长率均较浇铸膜差,吸水率在300%以上,高于浇铸膜.     

氯化镁增塑改性聚乙烯醇

以氯化镁为增塑剂, 采用流延法制备了增塑改性聚乙烯醇(PVA). 研究了氯化镁与PVA的相互作用以及氯化镁增塑改性PVA的结晶性能、 热性能和机械性能. 研究结果表明, 氯化镁能与PVA大分子发生较强的相互作用, 从而破坏PVA分子链内和链间的氢键, 降低PVA的结晶度. 氯化镁对PVA的热性能影响显著, PVA在加入氯化镁后的热分解过程由纯PVA的两段失重过程转变成三段失重过程. 氯化镁可有效增塑PVA, 其玻璃化转变温度降低, 拉伸强度下降, 断裂伸长率上升, 储能模量下降.     

六水合硝酸镁增塑改性淀粉-聚乙烯醇复合膜的合成与性能

以六水合硝酸镁[Mg(NO₃)₂·6H₂O]为增塑剂, 采用流延法制备了增塑改性的淀粉-聚乙烯醇(PVA)复合膜, 并研究了改性后淀粉-PVA复合膜的性能. 研究结果表明, Mg(NO₃)₂·6H₂O与淀粉和PVA发生一定的相互作用, 破坏了淀粉和PVA中的结晶结构. 因此, Mg(NO₃)₂·6H₂O的加入可提高淀粉与PVA间的相容性, 改变了淀粉-PVA复合膜的力学性能, 使其拉伸强度下降, 断裂伸长率提高.     

Adsorption versus covalent, statistically oriented and covalent, site-specific IgG immobilization on poly(vinyl alcohol)-based surfaces

Plain poly(vinyl alcohol) (PVA) surfaces, PVA surfaces tailored with additives (chitosan, chitosan-oligo) and PVA surfaces crosslinked with homo- or hetero-bifunctional amino-linkers (ethylenediamine, hexamethylenediamine, adipic acid dihydrazide, 3-aminophenylboronic acid) were evaluated for their ability to immobilize IgG. Immobilization strategies tested were adsorption as well as covalent, statistically oriented and covalent, site-specific binding of antibodies. The PVA surfaces were optimized with respect to the type of PVA, to PVA concentration and to glass substrate type. The resulting hydrogel surface of choice consists of 4% PVA coated onto adhesive glass. Comparison of modified and unmodified PVA surfaces revealed six surfaces which showed significantly higher loading capacity than plain PVA:PVA surfaces tailored with 2% chitosan resulted in twice greater fluorescence, whereas PVA surfaces oxidized using HIO₄ with and without further crosslinking using adipic acid dihydrazide revealed 2.6-2.8 times greater fluorescence. Yet the greatest fluorescence compared with plain PVA (up to 3.5 times as much) was achieved on PVA surfaces coupled with 3-aminophenylboronic acid activated by means of either 1% or 2.5% glutaraldehyde. Meanwhile, fluorescence signals were similar for statistically oriented IgG and IgG bound site-specifically using IgG activated with sodium meta-periodate.     

Masking Agents in Metal Titration with Edta Part IV - Thorium Titration in the Presence of Some Metals

Abstract

The authors studied the possible employment of various compounds containing sulfur as masking agents for divalent and trivalent metals, in the titration of thorium with EDTA. Reagents studied were thioglicolic acid, 3-mercaptopropionic acid, 2-mercaptoethanol, 2,3-dimercaptopropanol, BIS (2-hydroxy ethyl) dithlocarbamate, ethylxantate, thionalid, thiourea and thiosulfate.

The ones which proved more efficient were 2,3-dimercaptopropanol and BIS (2-hydroxyethyl) dithiocarbamate.     

疏水改性pH响应型智能水凝胶P(HEMA-NaAA-DiAC16)的制备及其溶胀性能

以二烯丙基胺和1-溴代十六烷为原料合成了疏水单体N,N-二烯丙基正十六烷胺(DiAC16),用FTIR、1H NMR 和元素分析对其进行了表征。 以2-羟基甲基丙烯酸乙酯(HEMA)、丙烯酸(AA)和N,N-二烯丙基正十六烷胺为共聚单体,N,N′-亚甲基双丙烯酰胺(BIS)为交联剂,十二烷基硫酸钠(SDS)为表面活性剂,过硫酸铵-四甲基乙二胺(TMEDA)为引发体系,制得的疏水改性智能水凝胶P(HEMA-NaAA-DiAC16)具有pH敏感特性。 研究了DiAC16、NaAA、BIS用量及pH值和离子强度等因素对水凝胶P(HEMA-NaAA-DiAC16)溶胀性能的影响。 结果表明,凝胶在水中的平衡溶胀率(为78.9～163.91),随DiAC16、BIS用量的增加和NaAA用量的减少而减少,n值(一般在0.5~1.0之间)随DiAC16、NaAA和BIS用量的增加而增加,为非Fickian扩散。 水凝胶的吸水溶胀是放热过程,ΔHm在-2.09～-3.64 kJ/mol,ΔHm的绝对值随DiAC16用量的减少、NaAA用量和BIS用量的增加而增大,聚合物与水的亲和力逐渐增强。 随离子强度的增强,平衡溶胀率下降。     

Preparation of electrospun chitosan/poly(vinyl alcohol) membranes

Electrospinning of chitosan from its solutions in 2% aqueous acetic acid was studied by adding poly(vinyl alcohol) (PVA) as a “guest” polymer. Properties of the chitosan/PVA solutions including viscosity, conductivity, and surface tension were measured, and effects of the polymer concentration, chitosan/PVA mass ratio and processing parameters (applied voltage, flow rate, capillary-to-collector distance) on the electrospinnability of chitosan/PVA were investigated. Analyses of scanning electron micrographs and transmission electron micrographs suggested that the chitosan/PVA ultrafine fibers were often obtained along with beads, and chitosan was located in the elctrospun fibers as well as in the beads. Uniform chitosan/PVA fibers with an average diameter of 99 ± 21 nm could be prepared from a 7% chitosan/PVA solution in 40:60 mass ratio. Results of Fourier transform infrared spectroscopy and X-ray diffraction demonstrated that there were possible hydrogen bonds between chitosan and PVA molecules, which could weaken the strong interaction in chitosan itself and facilitate chitosan/PVA electrospinnability. The electrospun chitosan/PVA membranes showed higher water uptake and would have potential applications in wound dressings.     

PVA改性PAMPS-PAM超高力学性能双网络水凝胶的制备

采用紫外光引发聚合制备了聚乙烯醇(PVA)改性的聚(2-丙烯酰胺基-2-甲基丙磺酸)-聚丙烯酰胺(PAMPS-PAM)双网络(DN)水凝胶.测定并比较了PVA改性前后PAMPS-PAM双网络水凝胶的溶胀动力学;通过扫描电子显微镜(SEM)观察了单网络水凝胶的结构;测定PVA改性前后PAMPS-PAM双网络水凝胶的压缩及拉伸性能.结果表明,经PVA改性后的PAMPS-PAM双网络水凝胶有较高的溶胀比;0.82%PVA用量的PAMPS-PAM双网络水凝胶在90%压缩形变率下仍保持完整、最大拉伸应力达到0.5 MPa,大幅提高PAMPS-PAM双网络水凝胶的力学性能.     

Performance Evaluation of Hybrid Gas–Liquid Pulse Discharge Plasma-Induced Degradation of Polyvinyl Alcohol-Containing Wastewater

A multi-needle-to-plate pulsed discharge plasma reactor was designed to investigate its potential for polyvinyl alcohol-containing wastewater (PVA) treatment. The effects of some operational parameters such as PVA initial concentration, pulse peak discharge voltage, air flow rate, solution pH value, and iron additives on PVA degradation were examined. The results indicated that PVA could be effectively degraded from aqueous solutions. PVA degradation efficiency was 76.0 % within 60 min’s discharge plasma treatment with 1.5 mmol L^?1 Fe²⁺ addition. Decreasing PVA initial concentration and increasing pulse peak discharge voltage were both beneficial for PVA degradation. There existed appropriate air flow rate for obtaining great PVA degradation efficiency in the present study. A little acid environment was conducive to PVA degradation. The presence of Fe²⁺ and Cu²⁺ could both benefit PVA degradation, and the increment of Fe²⁺ and Cu²⁺ concentrations to a certain extent could enhance its degradation efficiency, as well as energy yield. PVA possible degradation mechanisms were discussed, and the degradation processes were mainly triggered by the reactions of PVA with \(^{ \cdot } {\text{OH}}\) radicals.     

石墨负极表面聚合物功能保护膜对 锂离子电池存储寿命的提升

采用溶液浸渍法制备了聚乙烯醇(PVA)均匀包覆的石墨并研究了其微观形貌及电化学性能. 以LiNi_0.8Co_0.15Al_0.05O₂(NCA)为正极材料、 PVA包覆石墨为负极材料组装成软包电池和钢壳电池, 研究了PVA功能保护膜对全电池的电化学性能和存储寿命的影响. 结果表明, 存储过程中PVA功能保护膜可以有效抑制电解液和石墨内嵌锂反应的发生, 延长电池的存储寿命.     

Preparation and characterization of novel physically cross-linked hydrogels composed of poly(vinyl alcohol) and amine-terminated polyamidoamine dendrimer

Poly(vinyl alcohol) (PVA) and polyamidoamine (PAMAM) dendrimers are water-soluble, biocompatible and biodegradable polymers, which have been widely applied in biomedical fields. In this paper, novel physically cross-linked hydrogels composed of PVA and amine-terminated PAMAM dendrimer G6-NH(2) were prepared by cyclic freezing/thawing treatment of aqueous solutions containing PVA and G6-NH(2). The FT-IR analysis and elemental analysis indicated that PAMAM dendrimer G6-NH(2) was successfully introduced into the formed hydrogels, possibly via hydrogen bonds among hydroxyl groups, amide groups and amino groups in PVA and PAMAM dendrimer in the process of freezing-thawing cycle. Compared with physically cross-linked PVA hydrogel, PVA/G6-NH(2) hydrogels show higher swelling ratios and faster re-swelling rate due to the higher hydrophilicity of PAMAM dendrimer G6-NH(2). Higher contents of G6-NH(2) in PVA/G6-NH(2) hydrogels resulted in higher swelling ratios and faster re-swelling rates. With increasing freezing/thawing cyclic times, the swelling ratios and re-swelling rates of PVA/G6-NH(2) hydrogels decreased, which is similar to that of physically cross-linked PVA hydrogel. Combining the special host property of polyamidoamine dendrimer, these novel physically cross-linked hydrogels are expected to have potential use in drug delivery, including improving drug-loading amounts in hydrogels and prolonging drug release time. Swelling ratios of physically cross-linked PVA/G6-NH(2)-50 hydrogels prepared by three, six, nine freezing/thawing cycles. The swelling equilibrium experiments were carried out in distilled water at 25 degrees C.