大分子链转移剂活性对聚合物分散液晶电光性能的影响

采用可逆加成-断裂链转移(RAFT)、引发转移终止(Iniferter)、反向原子转移自由基聚合(RATRP)等活性自由基聚合方法,合成了分子量相近而带有不同端基的大分子链转移剂。通过紫外光聚合诱导相分离法制备聚合物分散液晶(PDLC)膜。通过研究大分子链转移剂光引发活性,发现采用RAFT聚合制备的大分子链转移剂具有较高的光活性,带有Iniferter活性基团的大分子链转移剂光活性很低。对不同大分子链转移剂制备的PDLC膜的电光性能进行比较,发现采用RAFT法合成的具有高光活性的大分子链转移剂能够使PDLC膜具有较高的开态透光率和较低的驱动电压。加入大分子链转移剂会导致PDLC记忆效应升高。     

氟树脂改性漆酚复合涂料的老化性能研究

采用氟树脂对漆酚进行改性,对改性后漆酚涂膜进行了自然老化和人工加速老化测试。通过傅立叶红外光谱(FTIR)、紫外光谱(UV)及扫描电镜(SEM)等手段对老化后的样品进行表征。结果表明,氟树脂含量在30%～90%(wt)时改性样品经过人工加速老化试验后表面出现破坏的时间大于漆酚涂膜,且经模拟太阳光照射120h后,失光率较小;暴露在自然环境中2880h后,表面仍未出现破坏现象。而漆酚涂膜在自然环境中暴露2544h后,表面已被破坏。研究表明,改性漆酚涂膜的耐老化性能较漆酚涂膜有大幅提高。     

三元巯基/乙烯基硅氮烷UV固化制备聚合物陶瓷前驱体

采用差光量热扫描研究了三元巯基化合物与乙烯基硅氮烷紫外光固化特性,结果表明,随着光引发剂浓度和辐照强度的增加,体系聚合速率增大,体系终止方式以自由基双基偶合终止为主。聚合反应为一级,且聚合速率与乙烯基浓度有关,而与巯基浓度无关。对制备的聚合物陶瓷前驱体的基本性能进行分析表明,玻璃化转变温度随巯基化合物用量的减少而降低,在巯基-乙烯基硅氮烷等摩尔比时,体系的固化度最大。     

三元巯基／乙烯基硅氮烷UV固化制备聚合物陶瓷前驱体

采用差光量热扫描研究了三元巯基化合物与乙烯基硅氮烷紫外光固化特性,结果表明,随着光引发剂浓度和辐照强度的增加,体系聚合速率增大,体系终止方式以自由基双基偶合终止为主。聚合反应为一级,且聚合速率与乙烯基浓度有关,而与巯基浓度无关。对制备的聚合物陶瓷前驱体的基本性能进行了分析,结果表明,玻璃化转变温度随巯基化合物用量的减少而降低,在巯基-乙烯基硅氮烷等摩尔比时,体系的固化度最大。     

Sterilizing photocurable materials by irradiation: preserving UV-curing properties of photopolymers following E-beam,gamma, or X-ray exposure

We have developed novel photopolymer gels to function as separators in blood collection tubes. By incorporating antioxidants such as α-tocopherol and nitroxides (TEMPO and TEMPOL), the new formulation can be sterilized with electron beam or gamma rays at a dose level of 17?kGy, without inducing premature curing of the photopolymers. For the blood separator gels that contain α-tocopherol, our results show that α-tocopherol plays a decisive role in impeding C-centered free radical propagation reactions through an H^?transfer mechanism. This mechanism involves the transfer of an H-atom from the hydroxyl group (OH) of α-tocopherol to the propagating C-centered radical leading to the termination of the polymerization. The sterilization radiation-induced premature curing of the photopolymer was also prevented in the blood separator gel containing nitroxides. For the gels containing TEMPO or TEMPOL, inhibition of the premature curing was achieved through an addition reaction or an H-transfer reaction, respectively. Our results also show that while α-tocopherol is not a contributing factor in the subsequent (time-of-use) UV curing of the gels, nitroxides enhance the UV curing process through nitroxide-mediated living free radical polymerization reactions leading to a decrease in UV curing time. The photopolymer separator gels are shown to function advantageously in clinical laboratory testing, especially for cell-free DNA measurements in blood.     

漆酚铁螯合高聚物的合成及其特性研究

用灼烧、红外光谱、质谱、热分析和分光光度法研究了漆酚与FeCl_3的反应关系、产物的组成和结构特征及其性能。由此揭示了传统黑推光漆的内在本质和特性,为黑推光漆的加工及提高性能等,提供了理论依据。此外还对漆酚与FeCl_3的反应机理进行了探讨。     

Metallopolymer capacitor in "one pot" by self-directed UV-assisted process

Silver metalized methacrylate films are prepared by single-step UV curing process with good conductivity on both sides. The major component of the composite is Bisphenol A ethoxylate dimethacrylate, which can be photopolymerized by a photoreactive initiator under UV light. Under the same conditions of UV irradiation, silver ions are deposited as metal nanoparticles while the pyrrole is oxidized to polypyrrole. The migration of silver ions and pyrrole toward both surfaces during polymerization leads to the formation of a metallo-polymer capacitor. The composite films are characterized by SEM-EDX and electrical measurements for possible applications as capacitors in flexible and/or nonplanar electronics.     

Concave micro-lens arrays fabricated from the photo-patternable GeO2/ormosils hybrid sol–gel films

Photo-patternable GeO₂/γ-glycidoxypropyltrimethoxysilane hybrid thin films were synthesized by a low-temperature sol–gel spin-coating technique. Optical properties and photochemical activities of the as prepared hybrid sol–gel films baked at different temperature were characterized by atomic force microscopy, prism coupling technique, UV–Visible spectroscopy, and Fourier transform infrared spectroscopy. The thermal stability of the gel powder obtained from the hybrid material sol was also examined by a thermal gravimetric analysis. Advantages for fabrication of concave micro-lens arrays based on the as-prepared photo-patternable hybrid films were demonstrated by a UV-cured imprint technique. Results indicate that the as-prepared photo-patternable hybrid materials have great applicability for the fabrication of photonic components. And the UV-cured imprint technique has advantages of simplicity, cost-effective, mass-production, and potential applications in industry production.     

Porogen residues detection in optical properties of low-k dielectrics cured by ultraviolet radiation

The optical properties of low dielectric constant (low-k) films have been determined by variable angle spectroscopic ellipsometry in the range from 2 eV to 9 eV to characterize the process of porogen removal during the UV-cure. The studied carbon doped oxide (SiCOH) porous dielectric films have been prepared by plasma enhanced chemical vapor deposition. The films have been deposited as a composition of a matrix precursor and an organic porogen. After deposition, the films have been cured by thermal annealing and UV irradiation (λ = 172 nm) to remove the porogen and create a porosity of 33%, reaching a dielectric constant of 2.3. The process of porogen decomposition and removal has been studied on series of low-k samples, UV-cured for various times. Additional samples have been prepared by the deposition and curing of the porogen film, without SiCOH matrix, and the matrix material itself, without porogen. The analysis of the optical response of the porous dielectric as a mixture of matrix material, porogen and voids, together with Fourier transform infrared analysis, allows the sensitive detection of the volume of the porogen and indicates the existence of decomposed porogen residues inside the pores, even for long curing time. The variation of the deposition and curing conditions can control the amount of the porogen residues and the final porosity.     

Polymerizabilities of amphiphilic monomers with controlled arrangements in Langmuir-Blodgett films

Polymerization of amphiphilic monomer Langmuir-Blodgett (LB) films, such as long-chain derivatives of -amino acids and diynoic, trienoic and acrylic acids, was studied. Multilayers of these monomers were prepared on CaF₂ or quartz plates by the LB method under various conditions, and polymerization processes were followed by IR and UV spectroscopy. The polycondensation of dioctadecyl- - glutamate proceeded easily in LB films at ordinary temperatures below the melting point without any initiation. All-trans- and 9-cis-9,11,13-octadecatrienoic acids polymerized very rapidly in LB films on UV irradiation. Photopolymerization in LB films of 10,12-tricosadiynoic acid was influenced by the deposition modes and annealing, and that of octadecyl acrylate was accelerated by the addition of the long- chain vinyl ether. In any case, polymerization reactions are markedly enhanced by a well-controlled arrangement of the monomer molecules in the LB films.     

高固低黏水性紫外光固化环氧丙烯酸酯的合成及性能

利用不同种类的稀释剂对环氧树脂进行降粘改性,而后与丙烯酸进行反应,合成得到具有光敏性的环氧丙烯酸酯,再用顺丁烯二酸酐对其接枝改性引入羧基,经有机碱中和成盐,得到可用于紫外光(UV)固化的高固低黏型水性环氧丙烯酸酯。讨论了反应温度、催化剂种类以及用量对反应的影响;测试了不同稀释剂对体系的降黏效果;并考察了固化漆膜的力学性能。结果表明:该光敏树脂具有固含量高、黏度低、固化速度快、固化后的涂膜硬度较高、对基材附着性好等特点。     

RAFT与点击化学结合制备UV固化丙烯酸树脂

以3-(苄硫基硫代羰基硫基)丙酸(BCTPA)为链转移剂,过硫酸铵(APS)/NaHSO3为氧化还原引发剂,用可逆加成-断裂链转移(RAFT)活性自由基乳液聚合制备了窄分布(PDI=1.21)的聚甲基丙烯酸烯丙酯(PAMA),并用核磁共振(1H-NMR)和凝胶渗透色谱(GPC)对其进行了表征,GPC测得PAMA数均分子量为7463,与通过单体转化率计算的理论分子量7483及氢谱计算分子量9358结果基本一致。采用巯基-烯烃点击反应对PAMA进行UV固化交联,固化后涂膜硬度由1H变为2H;耐水性测试表明,固化前40 min即发白,固化后24 h内仍未发白。PAMA固化前后的IR对照结果表明,固化后乙烯基信号3088 cm-1峰消失,表明烯丙基参与了固化交联反应。     

茶油基水性胺类环氧固化剂的结构与性能

以茶油皂脚脂肪酸甲酯为原料制备水性胺类环氧固化剂,通过热失重分析、力学性能测试等考察了封端剂种类、n(四乙烯五胺TEPA)∶n(单环氧甲基四氢邻苯二甲酸双酯SEMeTHP-DE)、脂肪醇聚氧乙烯醚(AEO)的聚合度及n(环氧)∶n(胺氢)对涂膜性能的影响。结果表明,选择苄基缩水甘油醚为封端剂,物质的量比n(TEPA)∶n(SEMeTHP-DE)为1.2∶1,聚合度为4的AEO(AEO-4)为亲水扩链剂制备的水性胺类环氧固化剂与水性环氧乳液AB-EP-20按n(环氧):n(胺氢)之比1.2∶1进行固化时,涂膜性能最佳,此时漆膜柔韧性1mm、铅笔硬度2H、附着力1级、耐冲击性≥50 kg.cm、耐水性(25℃)≥3d、耐乙醇性(25℃)≥3d。     

Experimental investigation and numerical modelling of the effect of the environment on the mechanical properties of polyurethane lacquer films

Polyurethane (PU) lacquer is a complex synthetic polymer. The mechanical properties of PU lacquers are influenced by the in-service environment, which may affect their function as protective coatings. As of date, limited research work has been published on the mechanical properties of PU lacquer films under environmental ageing conditions. This paper presents an investigation of the mechanical and hygroscopic behaviour of a commercial PU lacquer film. By means of water absorption and desorption tests, the diffusion coefficient and coefficient of hygroscopic expansion were determined. Tensile tests at constant displacement rates and creep tests under various UV/humidity ageing conditions showed a complex dependence of material properties on environmental conditions. A modified Burgers model with environment-dependent parameters is shown to satisfactorily model the mechanical behaviour of the PU lacquer in typical service conditions.     

Fabrication of a polyurethane acrylate/polyimide-based polymer mold for a hot embossing process

A high-thermal-resistance polymer-based flexible imprint mold was developed to be used in a hot embossing process. This mold was readily replicated in a UV curing imprint process and can be used as a mold for hot embossing and thermally curing imprint processes. The nano-sized pattern of this mold was not degraded by soaking at 350 degrees C for 10 min and the pattern fidelity was maintained after 10 separate cyclic heating tests between 0 degrees C and 350 degrees C. The substrate of this flexible mold was PI film, and a UV-cured polyurethane acrylate (PUA) layer was used to form the nano-scale patterns. The durability of this polymeric mold was tested by repetitive hot embossing processes. Nano-scale patterns of the mold were readily transferred to a PMMA layer coated onto a Si substrate by hot embossing lithography at 180 degrees C. After 10 cycles of hot embossing processes, no damage or degradation was observed in the flexible polymer mold. Using this polymer mold, patterns as small as 50 nm were successfully transferred to a Si substrate. Due to the flexibility of the polymer mold, nano-scale patterns were successfully transferred to a non-flat acryl substrate by hot embossing lithography.     

Non cell adhesive photopolymerized cross-linked layers (I): synthesis and characterization

The aim of this study is to design an effective hydrogel, which has good potential for application in the field of tissue regeneration. Ultimately, the polymeric biomaterial will be used as a bottom, non-cell adhering layer of a polymeric scaffold, which will inhibit the adhesion and proliferation of fibroblast cells. A series of terpolymer hydrogels were prepared from MMA/HPOEM/MePOEM monomers based on varying formulations. The gels were polymerized via free radical polymerization under UV and characterized by TGA, DSC and FTIR studies. Furthermore, the double bond conversion, gel content and swelling properties of the polymer were analyzed and correlated to its crosslinking density, which revealed details about the hydrogels character. Finally, cell culture experiments were used to compare the UV-cured polymer to its thermally derived non-functionalized polymer of the same formulation. Inverted optical microscopy was used to demonstrate cell-resistance of both materials with respect to a control Tissue Culture PolyStyrene plate. ©2003 Kluwer Acadamic Publishers     

Advanced polymer-inorganic hybrid hard coatings utilizing in situ polymerization method

Hard coatings are frequently used to give plastics high scratch resistance. Coating hardness and adhesion to the substrate are considered to be key factors influencing scratch resistance, but it is difficult to produce coatings that have both properties. Hybridization of polymers and inorganic materials is a promising approach for solving this problem. We prepared polymer-silica hybrid coatings by using in situ polymerization to carry out radical polymerization of vinyl monomers in a sol-gel solution of alkoxysilanes, and measured the abrasion resistance of the coatings. However, the expected properties were not obtained because the sol-gel reaction did not perfectly proceed on the surface of the coatings under the N2 conditions. We found that curing the hybrid coatings by UV irradiation in air promoted the sol-gel reaction on the surface, resulting in coatings having excellent abrasion resistance.     

Plasmapolymerisation für die Hartbeschichtung von Kunststofflinsen

The use of plastic as a substrate material for optical lenses has been increasing in importance due to smaller density, simpler machining and lower price. However scratches present a major problem wherever the lens surface is exposed to the environment. Various processes have thus been developed to protect the surfaces with hard coatings. The most common technique is the dipping process while spinning or spraying are other methodsto apply lacquer. Common to all these techniques are the required post treatments such as drying and heat or UV curing. Safety considerations as well as the long processing time and the handling required between the different steps, gave rise to the development of new technologies. Plasma polymerization, a technology relying on plasma enhanced chemical vapor deposition (PECVD), is used to deposit dense organic layers with reproducible, well defined surface properties. In contrast to dip coating, plasma polymerization even coats strongly curved structures with good uniformity. This is important for bifocal or trifocal lenses, featuring sharp edges on the surface. Due to the wide range of refraction indexes (about n = 1.5–1.8) available by using different monomers, even the latest high index materials can be coated without disturbing interference fringes. After a survey of plasma polymerization basics, some aspects of industrial equipment and processes for ophthalmic applications are presented. An outlook into the future of plasma polymerization for optical applications concludes the paper.     

Development of combinatorial chemistry methods for coatings: high-throughput optimization of curing parameters of coatings libraries

An automated analytical system has been implemented for the high-throughput optimization of processing conditions such as curing parameters in fabrication of UV-cured automotive organic protective coatings. Selection of optimum process conditions of combinatorial arrays of coatings is essential to correlate the high-throughput screening and conventional processes and to achieve the desired physical properties of coatings. For monitoring of curing conditions of each coating in the array, a viscosity-sensitive fluorophore 4,4'-bis(2-benzoxazolyl)stilbene was incorporated into coating formulations. This fluorescence tagging approach permitted us to combine a gradient temperature heater and a UV curing system with the full capabilities of our high-throughput screening system, including generation of spectroscopic data and its analysis. This investigation demonstrated the possibility of rapid decoupling of temperature and radiation effects in curing of UV-curable coating formulations by using multiple coatings and process conditions at once. While the system described here was implemented for high-throughput optimization of temperature conditions of radiation curing of arrays of organic protective coatings for automotive applications, this system can be further applied for a variety of other applications where optimization of process parameters can be studied in situ or off-line using optical spectroscopic tools.     

电子束作用下树脂体系的固化行为

根据电子束固化复合材料树脂体系的原理,从引入辐敏性的基团入手,合成了含硅丙烯酸酯的活性稀释剂、芳香族酰亚胺活性单体、含丙烯酸的PMR型聚酰胺酸和单官能、双官能的马来酰亚胺单体。在此基础上,对合成所得到的产物和几种环氧树脂进行了辐射交联实验,并考察与分析了不同树脂的辐射固化反应行为。与此同时对合成所得产物进行了表征,对固化物性能进行初步测试。所得研究结果,对电子束固化树脂体系的进一步研究具有重要的参考价值。