Compatibility enhancement of polyimide-silica hybrid sol-gel materials without incorporation of silane-coupling agent

A facile route has been developed to enhance compatibility between organic polyimide matrix and dispersed phase of inorganic silica particles without addition of conventional silane-coupling agent. The as-prepared hybrid sol-gel materials having reduced size of SiO2 particle dispersed in polyimide matrix were successfully synthesized through pre-catalyzed sol-gel route using an organic diamine base. The PI-silica hybrid materials through conventional polyamic acid-catalyzed sol-gel route with/without silane-coupling agent were also prepared for comparative control studies. Morphological feature of as-prepared sol-gel materials prepared from three different approaches was also compared based on the studies of transmission electron microscopy. Effects of the material composition, in three different catalyzed routes, were investigated by thermal stability, mechanical strength, optical clarity, gas barrier and water absorption measurements of polyimide and a series of polyimide-silica hybrid sol-gel materials, respectively.     

硅烷偶联剂对电子束固化碳纤维复合材料界面的增效研究

根据碳纤维表面的特点及其复合材料中树脂基体进行电子束固化的机理,对碳纤维表面进行预氧化以提高碳纤维表面含氧宫能团的含量,利用偶联剂的化学架桥作用对电子束固化复合材料界面进行了增效研究.采用X射线光电子能谱(XPS)对处理后碳纤维表面化学成分进行了分析,并采用层间剪切强度对电子束固化复合材料界面粘合性能进行了评价.结果表明,碳纤维表面的含氮官能团使电子束固化复合材料中碳纤维与环氧树脂基体之间的粘合强度减弱,偶联剂与预氧化碳纤维表面进行了强相互作用,使电子束固化复合材料层间剪切强度得到提高.     

UV固化含氟聚丙烯酸酯的制备

以甲基丙烯酸十二氟庚酯、丙烯酸-2-乙基己酯、甲基丙烯酸羟乙酯、苯乙烯为聚合单体,偶氮二异丁腈为引发剂,通过溶液聚合制得了含氟羟基聚丙烯酸酯共聚物(PGHES),以含异氰酸酯的不饱和单体HIp与共聚物PGHES侧链上的羟基反应制得光敏性含氟聚丙烯酸酯(U-PGHES)。用傅立叶红外光谱(FT-IR)、核磁共振氢谱(1 H-NMR)表征聚合物结构;用凝胶渗透色谱(GPC)及差示扫描量热仪(DSC)表征聚合物分子量及玻璃化转变温度;用光学接触角测量仪测量了聚合物固化膜接触角并计算得到表面能。结果表明,固化膜表面能随U-PGHES中含氟量的增加而降低,当含氟量达到9%时,表面能降低趋缓。     

UV固化聚氨酯-丙烯酸酯水性上光油的合成

以甲苯二异氰酸酯(TDI)、1,4-丁二醇(BDO)、聚醚二元醇(DL-1000)、二羟甲基丙酸(DMPA)和甲基丙烯酸羟乙酯(HEMA)为主要原料,合成纸张上光油UV固化聚氨酯-丙烯酸酯(PUA)乳液。用傅里叶红外光谱仪(FTIR)和激光纳米粒度仪等对其进行了表征,讨论了TDI/DL-1000摩尔比、-COOH含量、NCO/OH摩尔比和光引发剂等因素对乳液及涂膜性能的影响。研究表明,TDI/DL-1000的摩尔比为4,-COOH含量为2.1%(wt),NCO/OH的摩尔比为1.5时,制得的乳液的外观好,具有较高的光泽度和硬度,良好的耐水性和柔韧性等优异性能。使用TPO和184复配光引发剂且用量为3%(wt,下同)时光油固化速度最佳。     

硅烷偶联剂对电子束固化碳纤维复合材料的增效研究

根据碳纤维表面的特点及其复合材料中树脂基体进行电子束固化的机理,对碳纤维表面进行预氧化以提高碳纤维表面含氧官能团的含量,利用偶联剂的化学架桥作用对电子束固化复合材料界面进行了增效研究。采用X射线光电子能谱（XPS）对处理后碳纤维表面化学成分进行了分析,并采用层间剪切强度对电子束固化复合材料界面粘合性能进行了评价。结果表明,碳纤维表面的含氮官能团使电子束固化复合材料中碳纤维与环氧树脂基体之间的粘合强度减弱,偶联剂与预氧化碳纤维表面进行了强相互作用,使电子束固化复合材料层间剪切强度得到提高。     

Effect of silane-coupling agent on natural rubber filled with silica generated in situ

The effect of silane coupling agent was investigated for the novel in situ silica loading to the natural rubber (NR) matrix. The silica was generated in situ by the sol-gel reaction of tetraethoxysilane in the NR matrix before its crosslinking. -mercaptopropyltrimethoxysilane (-MPS) significantly prevented the delay of sulfur curing and increased the wettability of NR onto in situ silica, which resulted in the increase of reinforcement effect for the NR vulcanizate. -MPS decreased the interaction between the in situ silica particles followed by dispersing the in situ silica particles homogeneously and decreasing the hardness, compression set, hysteresis loss and storage modulus at the rubbery state of in situ silica-filled NR vulcanizate. The NR/in situ silica composite with -MPS is a promising material for a high performance rubber product.     

Surface modification of organic polymers with bioactive titanium oxide without the aid of a silane-coupling agent

Polyethylene (PE), polyethylene terephthalate (PET), ethylene-vinyl alcohol copolymer (EVOH), and poly(ε-caprolactam) (Nylon 6) were successfully modified with a thin crystalline titanium oxide layer on their surfaces by a simple dipping into a titanium alkoxide solution and a subsequent soak in hot HCl solution, without the aid of a silane-coupling agent. The surface modified polymers formed a bone-like apatite layer in a simulated body fluid (SBF) within a period of 2 days. PE, PET, and Nylon 6 formed an apatite layer faster and had a higher adhesive strength to the apatite. Three-dimensional fabrics with open spaces in various sizes containing such surface modified polymer fibers are expected to be useful as bone substitutes, since they may be able to form apatite on their constituent fibers in the living body, and thus, integrate with living bone.     

UV固化聚碳酸酯型聚氨酯丙烯酸酯的合成及性能研究

以聚碳酸酯二元醇(PCDL),异佛尔酮二异氰酸酯(IPDI)和甲基丙烯酸-2-羟乙酯(HEMA)为主要原料合成了可紫外光固化的聚碳酸酯型聚氨酯丙烯酸酯(PCDL-PUA)低聚物,利用傅立叶红外光谱仪(FT-IR),核磁共振仪(1H-NMR)和凝胶渗透色谱仪(GPC)对树脂的结构进行表征,并与聚己内酯二元醇(PCL220N)合成的PUA进行交联膜的力学性能和漆膜的耐化性比较.研究结果表明:PCDL合成的PUA的交联膜具有较高的拉伸强度和断裂伸长率;其漆膜也有优异的耐化性.     

可UV固化的超支化聚氨酯丙烯酸酯的合成与表征

通过两步法合成了可UV固化的超支化聚氨酯丙烯酸酯(HBUA).用SEC、FT-IR、1H-NMR和TG对HBUA进行表征,并测试了其UV固化膜的机械性能.结果表明:HBUA的分子量分布系数为2.31,丙烯酸端基改性程度为79.8%.HBUA的粘度较低有利于混合及涂布.UV固化膜具有高的硬度和良好的柔韧性.     

Back-surface gold mirrors for vibrationally resonant sum-frequency (VR-SFG) spectroscopy using 3-mercaptopropyltrimethoxysilane as an adhesion promoter

Back-surface mirrors are needed as reference materials for vibrationally resonant sum-frequency generation (VR-SFG) probing of liquid-solid interfaces. Conventional noble metal mirrors are not suitable for back-surface applications due to the presence of a metal adhesion layer (chromium or titanium) between the window substrate and the reflective metal surface. Using vapor deposited 3-mercaptopropyltrimethoxysilane (MPTMS) as a bi-functional adhesion promoter, gold mirrors were fabricated on fused silica substrates. These mirrors exhibit excellent gold adhesion as determined by the Scotch(?) tape test. They also produce minimal spectroscopic interference in the C-H stretching region (2800-3000 cm(-1)), as characterized by VR-SFG. These mirrors are thus robust and can be used as back-surface mirrors for a variety of applications, including reference mirrors for VR-SFG.     

Synthesis and characterization of PVP-coated large core iron oxide nanoparticles as an MRI contrast agent

The purpose of this study was to synthesize biocompatible polyvinylpyrrolidone (PVP)-coated iron oxide (PVP-IO) nanoparticles and to evaluate their efficacy as a magnetic resonance imaging (MRI) contrast agent. The PVP-IO nanoparticles were synthesized by a thermal decomposition method and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and a superconducting quantum interface device (SQUID). The core size of the particles is about 8-10 nm and the overall size is around 20-30 nm. The measured r(2) (reciprocal of T(2) relaxation time) and r2? (reciprocal of T2? relaxation time) are 141.2 and 338.1 (s mM)(-1), respectively. The particles are highly soluble and stable in various buffers and in serum. The macrophage uptake of PVP-IO is comparable to that of Feridex as measured by a Prussian blue iron stain and phantom study. The signal intensity of a rabbit liver was effectively reduced after intravenous administration of PVP-IO. Therefore PVP-IO nanoparticles are potentially useful for T(2)-weighted MR imaging.     

环氧大豆油改性UV固化水性环氧树脂的研究

合成制备了环氧大豆油改性水溶性UV固化环氧树脂,有效地改善了环氧树脂的柔韧性、水溶解性,成功地提高了成膜物的机械性能。同时讨论了环氧大豆油改性水性UV固化环氧树脂合成的反应温度、中和剂种类,反应物配比等对水性UV环氧树脂成膜物的影响,以此获得最佳配方。     

Synthesis and photocuring UV-curable/alkali-soluble properties of acrylic resin

以三苯基膦作催化剂,苯酐（PA）与丙烯酸羟乙酯（HEA）反应,合成了碱溶性光敏预聚物（PA-HEA）。通过对反应体系酸值的测定,研究了反应时间、配比、催化剂用量及投料方式对预聚物转化率的影响;通过将光引发剂加入预聚物,经紫外光固化后,考察了固化膜的耐酸性、碱液剥膜、热稳定性等性能。结果表明,在反应时间为3h,HEA与PA配比1∶0.75,催化剂含量1%（质量分数）时,转化率较高;固化膜能在10%盐酸中耐酸30min以上,且在1%NaOH溶液中2min内可完全脱膜,在32.6～137℃有较好的热稳定性。     

碱溶性光敏预聚物的合成与光固化性能研究

以三苯基膦作催化剂,苯酐(PA)与丙烯酸羟乙酯(HEA)反应,合成了碱溶性光敏预聚物(PA-HEA)。通过对反应体系酸值的测定,研究了反应时间、配比、催化剂用量及投料方式对预聚物转化率的影响;通过将光引发剂加入预聚物,经紫外光固化后,考察了固化膜的耐酸性、碱液剥膜、热稳定性等性能。结果表明,在反应时间为3h,HEA与PA配比1∶0.75,催化剂含量1%(质量分数)时,转化率较高;固化膜能在10%盐酸中耐酸30min以上,且在1%NaOH溶液中2min内可完全脱膜,在32.6～137℃有较好的热稳定性。     

Synthesis of copper nanoparticles using soybeans as a chelant agent

The preparation of stable, uniform copper nanoparticles by the formation of a complex Cu-soybeans extract and the reduction by sodium borohydride are reported in the present paper. It is a simple process for obtaining copper nanoparticles. The samples have been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), which reveal the nature of the nanoparticles. These studies reveal that the particles are mostly spherical in shape and have an average size of 20 nm. The UV-vis spectra show that an absorption band, occurring because of Surface Plasmon Resonance, exists at 545 nm; the size distribution is measured with DLS.     

硅烷偶联剂对磁性纳米微球的磁性能影响

以三氯化铁水溶液作原料,采用部分还原沉淀法,控制一些影响反应的参数。制备了纳米磁微粒子,并用硅烷偶联剂进行了表面修饰。利用透射电镜、红外光谱、X射线衍射等手段对磁微粒子的形貌、结构组成、磁化率、磁响应性进行了表征。结果表明所合成的磁微粒子平均粒径为18nm。分布均匀。具有较强的磁响应性。研究还表明偶联剂的加入会影响磁微粒子的磁性能,其加入量有一个适当值,使得改性后的磁微粒子的磁性能最强。     

Synthesis of silver nanoparticles using surfactin: A biosurfactant as stabilizing agent

Surfactin, a lipopeptide biosurfactant, was used to stabilize the formation of silver nanoparticles. Synthesis of silver nanoparticles using a borohydrate reduction was performed at three pH levels (pH 5, 7 and 9) and two different temperatures in the presence of surfactin. The nanomaterials were characterized by UV-vis spectroscopy, X-ray diffraction and transmission electron microscopy. The nanoparticles were synthesized at different pH conditions and temperature and remained stable for 2 months. The UV-vis spectra showed a surface plasmon resonance vibration band at 428 nm for all samples. TEM micrographs revealed that the mean nanoparticle size decreased with increase of pH from 5 to 9 (i.e. 17.8 ± 9.8, 6.9 ± 1.5 and 4.3 ± 1.1 nm) at 4 °C. However, at room temperature, size increased with pH (4.9 ± 1.4, 6.5 ± 1.6, 9.7 ± 4.3 nm at pH 5, 7 and 9 respectively). This report describes the use of a renewable, environmentally compatible, biodegradable surfactant as a stabilizing agent for the synthesis of silver nanoparticles.