含季铵基离子交换纤维的制备研究

以辐射接枝丙烯酸(AA)后的聚丙烯(PP)无纺布(PP-g-AA)为基材,采用紫外引发的方法接枝甲基丙烯酰氧乙基三甲基氯化铵(DMC),建立了一种制备阴离子交换纤维的新方法,得到了PP-g-AA-DMC纤维.研究了丙烯酸接枝率、DMC浓度、溶剂种类、光照时间,浸泡时间等因素对DMC接枝率的影响,结果表明,DMC的接枝率随着丙烯酸接枝率、DMC浓度、光照时间和纤维浸泡时间的增加而增大.接枝前后纤维的红外光谱分析表明,DMC被成功接枝在PP-g-AA基材上.吸附性能测定结果表明,纤维对水中以阴阳离子存在的金属铬均具有较好的吸附性能.     

丙烯酸β-羟丙酯与聚氯乙烯膜的紫外光接枝改性

采用液相接枝方法 ,在紫外线辐照下 ,合成了一系列丙烯酸 β-羟丙酯 (β -HPAT) /聚氯乙烯接枝膜。讨论了引发剂浓度、单体浓度、光照时间、光照强度对接枝率的影响。结果表明 ,引发剂浓度为 6 .5 1× 10 -3 mol/L ,单体浓度 2 .0mol/L ,光照时间为 2 .0h ,且光照强度越强时 ,接枝率最大。接枝膜的结构特征通过FT -IR光谱进行了确证 ,最后 ,对接枝膜进行TGA分析 ,结果表明聚氯乙烯经过表面改性后 ,表面极性增大 ,热稳定性大大提高。     

甲基丙烯酸甲酯在聚偏氟乙烯膜上的辐照接枝

采用电子加速器(EB)预辐照接枝的方法,在聚偏氟乙烯(PVDF)膜上接枝甲基丙烯酸甲酯(MMA),制备了PVDF-g-PMMA膜。研究了辐照剂量、单体浓度、反应温度、反应时间以及溶剂等因素对接枝率的影响规律。结果表明,接枝率随辐照剂量的增大而增加;反应初期接枝率随着单体质量分数的增大迅速增加,当单体质量分数达40%时,增加缓慢;单体质量分数达70%时,接枝率最高;从40℃开始接枝率缓慢上升,至60℃时陡增,之后接枝率基本不变;醇类是接枝反应很好的溶剂。用FT-IR、DSC分析了接枝物的组成及热性能。接枝膜成分为PVDF-g-PMMA共聚物,接枝膜在117℃处出现Tg峰,随着接枝率的增加该峰越来越明显,说明发生了接枝反应。随着接枝率的增加,熔融峰左移并最终消失,说明PMMA的接枝破坏了原PVDF膜的结晶性。吸液率随着浸泡时间的增加而增大,PVDF接枝膜达到的最大吸液率为290%,所需要的时间比原PVDF膜长。接枝率为50%的PVDF膜的离子电导率为6.0×10-3S/cm,吸液率达290%,MMA的接枝改善了PVDF电解质膜的电学性能。     

超临界CO2协助三单体接枝改性聚丙烯

利用超临界二氧化碳(SC CO2)作为单体的溶剂和聚丙烯的溶胀剂, 通过自由基接枝聚合合成了聚丙烯与丙烯酸、甲基丙烯酸甲酯以及马来酸酐的接枝产物PP-g-(AA-MMA-MAH). 在单体的选择上采取软、硬单体复配的方式来调节链的柔韧性. 考察了溶胀条件、接枝条件以及单体配比对接枝反应的影响, 研究结果表明, PP和单体以及引发剂在7.74 MPa、47 ℃下溶胀5 h后, 75 ℃下反应3 h时接枝率为4.31%, 接枝效率可达71.83%. 产品表征说明单体均匀地接枝到聚丙烯颗粒上; 改性后聚丙烯水润湿角降低, 亲水性能得到明显改善; 接枝单体的引入提高了PP的热稳定性.     

聚砜与丙烯酸的紫外光辐射接枝共聚及其表征

在均相溶液体系下,运用紫外光辐射引发合成了聚砜与丙烯酸的接枝共聚物。用化学滴定、漫反射傅立叶变换红外光谱和热分析等技术对接枝聚合物进行了表征。结果表明:丙烯酸被接枝在聚砜链上;光照时间、单体浓度和光引发剂浓度对接枝率均有较大影响。膜表面接触角的研究表明,接枝共聚物膜的亲水性比改性前有所提高。     

电晕放电引发丙烯酸表面接枝LDPE薄膜的研究

本文采用接枝量测定、ATRIR和ESCA研究了电晕放电引发丙烯酸表面接枝LDPE薄膜,实验结果表明:电晕放电能有效地引发丙烯酸在LDPE薄膜表面的接枝聚合反应,随反应时间延长、反应温度提高和丙烯酸单体浓度增大,表面接枝量增大。当丙烯酸浓度为20%、聚合温度为70℃、反应15小时时,经电晕放电处理72秒后的LDPE薄膜表面接枝量高达22055μgcm2。     

添加型聚丙烯大分子表面改性剂PP-g-PEG的制备及其应用

以马来酸酐为桥联剂,通过其与单端羟基聚乙二醇的反应,合成了大分子表面改性剂聚丙烯-聚乙二醇接枝共聚物,探索了反应条件对接枝反应的影响,用IR、NMR、TGA、DSC对接枝物的结构及性能进行研究,并通过共混研究了接枝物对聚丙烯的表面改性效果.结果表明,提高马来酸酐接枝聚丙烯或聚乙二醇的分子量,会阻碍接枝反应的进行,接枝率明显下降;接枝聚乙二醇降低了接枝物的结晶能力;聚丙烯-聚乙二醇接枝共聚物的热稳定性随着聚乙二醇的含量增加及侧链聚乙二醇长度的增加略有下降;聚丙烯-聚乙二醇接枝共聚物组分在共混物中具有明显的向外择优迁移特性,可以作为聚丙烯的添加型表面改性剂使用.     

聚丙烯表面接枝PNIPAAm膜Ⅰ.光接枝反应和表面形态结构研究

以氧杂蒽酮或二苯甲酮为引发剂 ,通过紫外光引发表面接枝聚合的方法在聚丙烯薄膜表面引入了具有温度敏感特性的聚异丙基丙烯酰胺 (PNIPAAm)接枝聚合物层 .提高紫外光强度和接枝反应温度均有利于接枝率增大 ,而单体浓度对接枝率的影响存在最佳值 ,为 0 1 8mol L .在引发剂预浸渍引发接枝和休眠基引发接枝这两种方式中 ,后者能够实现更高的接枝率 .红外光谱 (FTIR)、X射线光电子能谱化学分析 (ESCA)和扫描电子显微镜 (SEM)等对接枝层组成的表征结果证实了接枝层的存在 .在不同温度下 ,接枝膜的FTIR谱图中酰胺I带和酰胺II带特征吸收峰发生位移 ,表明它具有温度敏感特性 .同时 ,SEM研究发现由于接枝膜的温度敏感特性而导致的球状表面形态结构     

丙烯酸改性聚醚砜中空纤维渗透汽化膜的研究

采用自由基聚合反应制备了丙烯酸接枝改性的聚醚砜中空纤维渗透汽化膜,该膜用于醇／水分离获得了良好的效果。结果表明,通过改变聚合单体的浓度可以控制膜的接枝率,并调节膜的选择性和通量。改性膜的红外光谱和电镜分析结果表明：膜的接枝反应主要发生在中空纤维膜的内表面,膜的外表面接枝程度很低。力学性能测试表明接枝后膜的拉伸强度减弱。     

一种新型亲水性有机-无机渗透蒸发分离膜——聚丙烯酰胺复合膜的制备

将纳米二氧化硅微孔膜用γ-(甲基丙烯酰氧基)丙基三甲氧基硅烷处理,再通过自由基聚合接枝丙烯酰胺单体制备出一种新型的亲水性有机-无机复合膜.用TGA测定了单体在二氧化硅粉末上的接枝率;用SEM和AFM观察了接枝反应前后膜表面形态的变化;系统研究了接枝单体浓度对膜的渗透蒸发分离性能的影响.结果表明,这种膜用于醇水和丙烯酸水溶液的分离有很好的选择性和渗透性;在丙烯酰胺质量分数为3%的溶液中接枝的膜有较好的分离性;溶液浓度和操作温度对膜渗透性的影响非常特殊.     

Visible light‐induced living surface grafting polymerization for the potential biological applications

A novel visible light‐induced living surface grafting polymerization was developed by a strategy in which isopropyl thioxanthone (ITX) was first photoreduced under UV light and sequentially coupled onto the surface of polymeric substrates, and the produced isopropyl thioxanthone‐semipinacol (ITXSP) “dormant” groups were subsequently reactivated under visible light to initiate a surface grafting polymerization. By using glycidyl methacrylate (GMA) and low‐density polyethylene (LDPE) films as models, a “living” surface grafting polymerization initiated by ITXSP under visible light at room temperature was observed. Both the surface grafting chain length versus grafting conversion of monomer and the grafting polymerization rate versus monomer concentration demonstrated a linear dependence, which is in accord with the known characteristics of living polymerization. The livingness rendered it possible to accurately control the thickness of the grafted layer by simply altering the irradiation time. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Phys, 2009     

芴酮引发光接枝改性LDPE膜的研究

采用紫外光引发接枝表面改性的方法,以芴酮(FL)为引发剂,在低密度聚乙烯(LDPE)薄膜表面上接枝丙烯酸(AA)、甲基丙烯酸(MAA)、丙烯酸甲酯(MA)、甲基丙烯酸甲酯(MMA)、丙烯酰胺(AM)等单体,以赋予薄膜表面新的化学性质.考察了引发剂浓度、紫外光的辐照时间、辐照强度、单体种类对LDPE薄膜接枝程度的影响.结果表明,在一定范围内,增加芴酮浓度,可以提高单体的接枝率,但当芴酮浓度达到5%时,接枝率反而下降.延长辐照时间至4 min和提高紫外光的辐照强度达100 W/m2,均有利于接枝反应的进行.不同单体在LDPE膜上的接枝能力与单体的活性、单体与基材的相容性等因素有关.接枝后,LDPE与水的接触角下降程度不仅与单体在膜上的接枝量有关,还与接枝单体的亲水性能密切相关.     

MMA/DVB emulsion surface graft polymerization initiated by UV light

Methyl methacrylate/1,2-divinylbenzene (MMA/DVB) in an opaque emulsion were successfully grafted onto the surface of polymeric substrate under the irradiation of UV light with benzophenone (BP) as a photoinitiator that was previously coated on the substrate surface. Monomer conversion, grafting efficiency, and grafting yields were determined by the gravimetric method. ATR-IR, AFM, and TEM were used to characterize the surface composition, to observe the topography of the grafted substrates, and to view inter-film colloid particles formed by cross-linking. The results reveal that, with the opaque MMA/DVB emulsion system and CPP film as substrate, the monomer conversion is in the range of 15-55%, the grafting efficiency is about 80%, the grafting yield reaches 5%, and the thickness of the graft layer can be controlled in the range 0.09-1.5 microm. Images of AFM show that the graft layer is piled up by nanoparticles (about 30-50 nm in diameter), which are linked together and tied to the substrate surface with covalent bonds. A possible model of surface graft polymerization including surface initiating, nucleation, and shish kebab growing is put forward to interpreting the above results.     

PREPARATION OF LOW MOLECULAR WEIGHT POLY（GLYCIDYL METHACRYLATE） BY PHOTOPOLYMERIZATION

Low molecular weight poly（glycidyl methacrylate）s （PGMAs） were prepared by photopolymerization in ethyl acetate, with benzophenone （BP） as photoinitiator, and triethylamine （TEA） as hydrogen donor. The existence of semipinacol dormant end groups in PGMA was confirmed by FT-IR and ^1H-NMR, and the content of the semipinacol dormant groups was determined quantitatively by ^1H-NMR measurement. The effects of various thctors, such as reaction time, BP concentration and monomer concentration on the synthesis of the polymers were investigated systematically. The molecular weights of the polymers were also investigated with GPC. It is shown that increasing BP concentration and decreasing irradiation time and monomer concentration led to a significant decrease of the molecular weights.     

UV-induced Self-initiated Graft Polymerization of Acrylamide onto Poly(ether ether ketone)

Photo-grafting of hydrophilic monomer was used to enhance the hydrophilicity of poly(ether ether ketone) (PEEK) with the aim of extending its applications to biological fields. PEEK sheets were surface modified by grafting of acrylamide(AAm) with ultraviolet(UV) irradiation in the presence or absence of benzophenone(BP). The effects of BP, irradiation time and monomer concentration on the surface wettability of PEEK were investigated. Characterization of modified PEEK using scanning electron microscopy(SEM), energy-disperse spectrometer(EDS) and water contact angle measurements shows that AAm was successfully grafted on PEEK surface both in presence and absence of BP. With the increase in irradiation time and monomer concentration, contact angles decrease to as low as 30°, demonstrating a significant improvement of surface hydrophilicity. In agreement with the decrease in contact angle, under identical conditions, the nitrogen concentration increases, suggesting the increase in grafting degree of the grafting polymerization. This investigation demonstrates a self-initiation of PEEK due to its BP-like structure in the backbone of the polymer. Though the graft polymerization proceeds more readily in the presence of BP, the self-initiated graft polymerization is clearly observed.     

Surface‐confined photopolymerization of single‐ and mixed‐monomer systems to tailor the wettability of poly(L‐lactide) film

The major objective of this research was to modify the surface characteristics of poly(L ‐lactide) (PLA) by grafting a combination of hydrophilic polymers to produce a continuum of hydrophilicity. The PLA film was solvent cast, and the film surfaces were activated by ultra violet (UV) irradiation. A single monomer or combination of two monomers, selected from vinyl acetate (VAc), acrylic acid (AA), and acrylamide (AAm), were then grafted to the PLA film surface using a UV induced photopolymerization process. The film surfaces resulting from each reaction step were analyzed using ATR‐FTIR spectroscopy and contact angle goniometry. Results showed that AAm dominated the hydrophilicity of the film surface when copolymerized with VAc or AA, while the water contact angles for PLA films grafted with poly(vinyl acetate‐co‐acrylic acid) varied more gradually with feed composition. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6534‐6543, 2006     

低密度聚乙烯丙烯酸气相光接枝体系反应机理的研究

研究了以二苯甲酮 (BP)为光敏剂 ,丙烯酸在低密度聚乙烯 (LDPE)膜上两步法气相光接枝聚合 ;从反应的基本要素出发 ,利用紫外光分光光度计跟踪测定了二苯甲酮在LDPE膜中的扩散情况 ,发现其扩散系数随BP浓度的升高而降低 ,约在 0 8～ 2 0× 10 -12 m2 ·s-1之间 .同样方法跟踪测定了BP在不同条件下的光还原反应 ,结果表明 :当远紫外光被滤掉后 ,其半衰期大大加长 ,氧气的存在更是加剧了这一效应 ;并且通过测定不同条件下气相光接枝聚合的一些基本规律 ,提出单体扩散为该气相光接枝聚合的控制步骤     

Surface graft polymerization of acrylamide onto poly(ethylene terephthalate) film by UV irradiation

To improve the low water wettability of poly(ethylene terephthalate) (PET), graft polymerization of acrylamide (AAm) by UV irradiation was performed onto the surface of a PET film with the simultaneous irradiation method without using a photo sensitizer. The PET film immersed in a 10 wt % deaerated aqueous solution of AAm was found to become highly hydrophilic upon UV irradiation. Optical microscopy on cross sections of grafted films showed that localization of the graft polymerization was restricted to a thin surface region of the film. Both the low concentration of polymer radicals formed by UV irradiation and the monomer penetration limited to the film surface would be responsible for localization of the grafted layer to the film surface region. Pretreatment of the PET film with benzyl alcohol was effective for enhancement of the graft polymerization. Retention of high hydrophilicity of the surface even after rigorous extraction of homopolymer and a comparative study of polymerization without UV irradiation strongly suggested that UV irradiation of the PET film under immersion in the deaerated AAm aqueous solution would lead to formation of the true graft copolymer.     

Evidence and mechanisms of filling polymerization by plasma-induced graft polymerization

Using a plasma-induced graft polymerization technique, which is well known as a surface modification method, the grafted polymer was formed in pores of the porous material. This study examined the filling mechanism. Five thin porous films were sandwiched together, and employed as the substrate. The substrate was treated by plasma, and the change in surface tension and radical formation was measured for each sheet after the sheet was separated. The only surface on which surface-tension change was detected, was that of the sheet directly exposed to the plasma. Although plasma treatment made polymer radicals primarily on the outer surface of the sheet, the treatment also formed a few radicals inside the sheets. The radicals inside the sheets reacted with methylacrylate and grafted polymer formed in the pores. The location of grafted polymer depended on the balance between monomer diffusivity and reactivity. The grafting rate depended on which monomer solvent was used for the polymerization. Thus, the grafted membrane morphology could be controlled by varying the grating solvent composition. © 1996 John Wiley & Sons, Inc.