紫外光引发LDPE膜接枝含氟丙烯酸酯的研究

通过紫外光引发表面接枝聚合反应的方法 ,把含氟丙烯酸酯单体R 5 6 1 0引到LDPE薄膜上 .对经丁酮抽提后的接枝膜进行FTIR、ESCA、SEM和DSC等表征 ,证实含氟聚合物以化学键的方式接枝在LDPE基体膜上 .在一定范围内 ,增加紫外光强、引发剂和单体浓度以及反应温度等均有利于提高接枝率 .经计算R 5 6 1 0的紫外光引发接枝聚合反应总活化能为 5 4 2kJ mol.接枝膜的接触角随着接枝率的提高逐步增大 ,直至趋于恒定 .作者提出接枝膜存在一个在接触角测定时影响基体膜与探测水滴相互作用过程的边界层 .当接枝率较低、接枝层厚度小于边界层临界厚度时 ,基体LDPE影响接触角的大小 ,但随着接枝率提高 ,接枝层逐渐变厚 ,氟聚合物层对接触角的贡献逐渐占优势 ,导致接触角随之增大 .当接枝率超过一定值以后 ,接枝层厚度超过边界层临界厚度 ,接枝层对接枝膜的接触角起全部贡献 ,接触角测定值随之稳定     

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。     

电火花引发HEMA 接枝LDPE 薄膜及其血液相容性

采用接枝量、ATR－IR、SEM、与水接触角、溶血试验和再钙化时间等测试手段研究了电火花引发甲基丙烯酸β－羟乙酯(HEMA)表面接枝低密度聚乙烯(LAPE)薄膜的接枝聚合反应影响因素、表面结构和血液相容性。结果表明,电火花能有效引发HEMA在LDMA薄膜表面接枝聚合反应,随接枝聚合反应时间延长、单体浓度的增大。接枝量增大。随反应温度升高,接枝量增大到一最大值后,进一步升高反应温度,接枝量下降,最佳接枝聚合温度为60℃当在60℃单体φ=5％水溶液是反应2h时,经空气气氛和1.5kV电火花预处理72s和LDPE薄膜表面接枝量可达169ug/cm^2。接枝改性后LDPE薄膜与水的接触下降,亲水性增加,溶血程度减小,再钙化时间延长,血液相容性得到改善。     

电火花引发HEMA 接枝LDPE 薄膜及其血液相容性

采用接枝量、ATR－IR、SEM、与水接触角、溶血试验和再钙化时间等测试手段研究了电火花引发甲基丙烯酸β－羟乙酯(HEMA)表面接枝低密度聚乙烯(LAPE)薄膜的接枝聚合反应影响因素、表面结构和血液相容性。结果表明,电火花能有效引发HEMA在LDMA薄膜表面接枝聚合反应,随接枝聚合反应时间延长、单体浓度的增大。接枝量增大。随反应温度升高,接枝量增大到一最大值后,进一步升高反应温度,接枝量下降,最佳接枝聚合温度为60℃当在60℃单体φ=5％水溶液是反应2h时,经空气气氛和1.5kV电火花预处理72s和LDPE薄膜表面接枝量可达169ug/cm^2。接枝改性后LDPE薄膜与水的接触下降,亲水性增加,溶血程度减小,再钙化时间延长,血液相容性得到改善。     

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。     

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。     

N,N-二乙基丙烯酰胺与丙烯酸在聚丙烯薄膜表面光接枝制备二元接枝膜及其温度、pH值敏感特性研究

以二苯甲酮为引发剂,聚丙烯薄膜(CPP)为基材,通过紫外光接枝的方法制备了具有温度和pH值双重敏感特性的聚N,N-二乙基丙烯酰胺(PNDEA)与聚丙烯酸(PAA)二元接枝膜.在PNDEA一次接枝膜的制备过程中,引发剂与单体配比相同时,本体接枝方法的接枝速率在反应初期明显高于溶液接枝方法;采用溶液法时,增大引发剂与单体配比等可提高接枝率.用本体法所制得的PNDEA一次膜光活化接枝PAA时接枝速率较溶液法高,并且能够实现较高的PAA接枝率.用红外光谱(FTIR)、X射线光电子能谱化学分析(ESCA)对接枝层组成的表征结果证实了二元接枝层的存在.在不同温度下,PNDEA一次接枝膜的FTIR谱图中酰胺Ⅰ带特征吸收峰发生位移表明它具有温度敏感特性.用扫描电子显微镜(SEM)对PNDEA接枝层表征结果表明,用不同接枝手段所制备的接枝膜具有不同的表面形貌.通过吸水率测定研究了二元接枝膜的温度及pH值敏感特性.     

多官能单体TMPTA在LDPE表面光接枝聚合研究

以二苯甲酮(BP)为光引发剂、丙酮和水的混合物为溶剂,研究了室温下多官能单体三羟甲基丙烷三丙烯酸酯(TMPTA)在低密度聚乙烯(LDPE)表面的光接枝聚合(λ>300nm).研究表明,多官能单体的接枝速率较快,接枝聚合易产生交联结构,聚合后仍残留双键;延长聚合反应时间、增加单体用量有利于单体接枝转化率的提高;随引发剂用量增加,单体接枝转化率出现一峰值;在研究范围内,混合溶剂中水含量增加可使单体接枝转化率明显提高.扫描电镜观察到接枝膜表面形成了许多小球,表面粗糙度增加,疏水性提高.     

UV辐照接枝制备酚酞基聚芳醚酮纳滤膜——链转移剂的作用

酚酞基聚芳醚酮(PEK-C)超滤膜的表面通过紫外辐照接枝丙烯酸(AA)可以制备对II价盐有很好截留率的亲水性纳滤膜. FTIR-ATR、表面接触角、SEM和AFM的研究结果表明, 在接枝单体溶液中加入异丙醇(i-PrOH)作为链转移剂并不影响AA在PEK-C超滤膜表面的接枝反应. 得到的改性膜同样具有优良的纳滤性能. 与不加i-PrOH的AA改性膜相比, 新合成的膜有较高的滤出液通量, 该膜对盐离子的截留率虽有所降低, 但可以通过增加接枝反应时间和辐照光源的强度来提高. i-PrOH的浓度对膜的分离性能的影响很大, 在低浓度时, 改性膜对离子的截留率会有所下降, 继续提高i-PrOH的浓度, 膜的截留率不再变化而滤出液通量会有成倍的增加, 表明链转移剂的存在可能会提高膜的接枝密度, 增加膜的表面电荷, 使膜对离子的截留率保持不变.     

Applicability of photochemically generated pendant benzoyl peroxides in both “grafting from” and “grafting to” techniques

Methyl methacrylate and styrene copolymers containing pendant benzil groups, such as 1-[4-(2-methacroyloxyethoxy)phenyl]-2-phenyl-1,2-ethanedione-co-methyl metacrylate (BzMA/MMA), 1-[4-(2-methacroyloxyethoxy)phenyl]-2-phenyl-1,2-ethanedione-co-styrene (BzMA/S), and 1-phenyl-2-(4-propenoylphenyl)-1,2-ethanedione-co-styrene (PCOCO/S), were prepared and used as precursors for photochemically generated pendant benzoyl peroxides. Decomposition of the pendant benzoyl peroxides was subsequently used in grafting processes. Either irradiation or a combination of irradiation with subsequent thermal treatment was adopted for grafting a thin layer of BzMA/MMA copolymer onto the surface of LDPE films. The grafting resulted in a significant decrease in contact angle of the film surface. The same activation strategy was successfully adopted to initiate the polymerisation of acrylic or methacrylic acids from the surface of styrene copolymer films containing the initiator precursor in the polymer side chains (BzMA/S and PCOCO/S). The successful surface grafting was proved by contact angles measurement as well as by infrared spectroscopic analysis.     

光引发N-乙烯基吡咯烷酮在嵌段聚醚聚氨酯膜上接枝聚合的研究

本文研究了在碱性介质中,氮气氛下 N-乙烯基吡咯烷酮(N-VP)在嵌段聚醚聚氨酯(SPEU)膜上的接枝聚合。测定了接枝率与接枝液中 N-VP单体浓度、光照时间、催化剂浓度等条件的关系。测定了接枝后 SPEU 膜的吸水性,并用扫描电镜对膜表面进行了观察。对碱性介质中的接枝机理进行了初步探讨。     

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     

Surface modification of LDPE film by CO2 pulsed laser irradiation

The influence of the pulsed CO₂ laser irradiation on the surface structure of the LDPE film was investigated. Significant changes were observed on the surface of laser treated films as it was verified by the attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy and contact angle-measurement. Formation of polar functional groups onto the LDPE surfaces exhibited by the ATR-FTIR spectra was shown to be strongly dependent on the number of the CO₂ laser pulses. The intensity of the polar groups increased with increasing the number of pulses up to two and then slightly decreased at three laser pulses. This was also confirmed with the contact angle measurements in which the sample subjected to two laser pulses showed the highest wettability i.e. the lowest water drop contact angle. The concentration of peroxide groups formed on the surface of the laser treated films was determined quantitatively by UV spectroscopic method using iodide procedure. The latter results showed a similar trend with the results obtained using FTIR spectroscopy.     

二步法聚丙烯/丙烯酸表面接枝聚合研究

研究了二步法聚丙烯膜表面的丙烯酸接枝反应 .实验发现 ,以醋酐为溶剂的反应体系所得接枝率明显好于以水为溶剂的体系 ;接枝率随光敏剂浓度、单体浓度增大而增加 ;提高反应温度 ,可使接枝率明显增大 ;接枝后的聚丙烯膜表面亲水性可明显改善 .并用红外光谱证实了丙烯酸在聚丙烯膜表面的接枝 .     

Multiple levels hydrophobic modification of polymeric substrates by UV‐grafting polymerization with TFEMA as monomer

The hydrophobic solid surface modification with fluorine‐containing monomers has received tremendous attention because of its unique structure and excellent property. However, these hydrophobic films normally suffer from two major problems: one is weak interface interaction between fluoropolymers and substrates, and the other is the high cost of fluorine‐containing monomers. Herein, with the aim of feasible industrial application, a facile in situ UV photo‐grafting method is reported, which could ensure the formation of chemical bonds between fluoropolymer‐grafted layer and substrate with a low cost commercial 2,2,2‐trifluoroethyl methacrylate (TFEMA) as monomer. With low‐density polyethylene (LDPE) film as a model substrate, four kinds of poly‐TFEMA‐grafted layer are fabricated on LDPE films with different surface morphologies: polymer brush, polymer network, crosslinked nanoparticles, and a micro‐ and nanoscale hierarchical structure. The experimental results showed that the water contact angles (CAs) of the LDPE films grafted with polymer brush, polymer network, and crosslinked nanoparticles were (103 ± 2)°, (95 ± 2)°, and (122 ± 2)°, respectively, which were much higher than that of LDPE film. The introduction of micro‐ and nanoscale hierarchical structures can dramatically improve the surface roughness, which will further enhance the film hydrophobicity, and the water CA can reach as high as (140 ± 1)°. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1059–1067     

紫外光照射对掺铝氧化锌薄膜导电和透光性质的影响

本文采用光助溶胶—凝胶法制备了掺铝氧化锌(AZO)透明导电薄膜.研究了紫外光照射对薄膜导电性和透光性质的影响.结果表明:光照使薄膜的导电性显著提高,且光照后薄膜方阻的降低幅度随薄膜晶粒尺寸的减小而逐渐增加;而随着紫外光照射时间延长,薄膜的紫外吸收边蓝移,近红外区透光率降低.以上实验现象可能与表面吸附氧解吸引起的载流子浓度增加、迁移率升高以及分层退火处理形成的薄膜结构有关.     

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     

Surface changes brought about by corona discharge treatment of polyethylene film and the effect on subsequent microbial colonisation

Microbial colonisation of synthetic plastic films is normally slow, which affects the total period of biodegradation. Correlation between the modified surface condition and the ability for microorganisms to colonise low-density polyethylene (LDPE) film was studied. Corona discharge treatment was applied to obtain enriched and activated surface condition of LDPE film. It was found from water contact angle and FTIR spectrum evaluations that surface energy was significantly increased due to production of free radicals. Stabilised oxidised LDPE surface was also obtained by further exposure to the corona which gave more suitable condition for subsequent colonisation. Results were compared with UV irradiated (photo-oxidised) LDPE films. Colonisation of corona discharged and UV treated LDPE films were tested in the laboratory environment using known fungal isolates and in a natural compost environment. More active microbial colonisation was observed in all cases for corona discharged and UV treated LDPE films. Far longer UV exposure was required to have the same physicochemical and biological effect as the corona discharge treatment.