木质素炭与ZSM-5联合催化热解木质素制备芳烃实验研究

为了提高木质素催化热解所得芳烃的产率,本研究以碱木质素为原料,在碱木质素炭和ZSM-5的二元催化体系下进行快速热解实验,选取催化剂比例、热解温度、热解时间等为实验变量,探究碱木质素热解产物中芳烃的变化规律以及碱木质素炭和ZSM-5协同催化作用机理。结果表明,碱木质素催化热解所得芳烃的产量从17 mg/g(未加炭)提高到33 mg/g(炭添加量为1 g),产率增加了近一倍。通过不同工况研究发现,碱木质素快速热解制备芳烃的最佳条件是:碱木质素∶碱木质素炭∶ZSM-5=1∶1∶1,热解温度为500℃,热解时间为10 min。机理分析表明,热解过程中碱木质素炭主要起断键作用,而ZSM-5起择形芳构化作用,两者协同作用得到更高的芳烃产率。     

磺甲基化木质素的辣根过氧化物酶催化聚合研究

以碱木质素为原料,采用磺甲基化反应,得到磺甲基化木质素(SAL),并进一步采用辣根过氧化物酶(HRP)催化以提高其分子量,制备了高分子量高磺化度磺甲基化木质素(HPSAL).采用凝胶渗透色谱、红外光谱、核磁共振氢谱、紫外光谱和顶空气相色谱等研究了改性前后SAL的结构特征.结果表明,经HRP催化后,与SAL相比,HPSAL的重均分子量和磺化度显著增加,分别提高20倍和30%以上,羧基含量升高,而甲氧基和酚羟基含量降低.HRP使SAL形成酚氧自由基,活化其酚羟基的邻、对和侧链Cβ位,增加磺化反应活性,而磺化度的提高又有利于增加HRP催化SAL的聚合反应活性,其聚合方式主要为β-O-4'、β-β'、β-1'和β-5'联结.分子模拟结果表明,甲氧基含量的降低和磺酸基含量的增加能显著提高以β-O-4'连接键为主的聚合反应活性.     

紫外接枝聚合聚乙二醇甲基丙烯酸甲酯制备抗污染聚砜超滤膜

以二苯甲酮(BP)为紫外引发剂,将聚乙二醇甲基丙烯酸甲酯(PEGMA)接枝在聚砜超滤膜表面以提高膜的抗污染性能.在二苯甲酮存在的条件下,波长较长(λ300nm)的紫外光(UV)辐射下发生提氢反应,可以有效防止聚砜分子主链的剪切,保持改性膜的分离性能.考察了PEGMA浓度、UV辐射时间和BP浓度对改性超滤膜接枝度、亲水性和抗污染性能的影响.用表面全反射红外光谱(ATR/FTIR)表征改性前后膜表面化学组成的变化.表面改性膜的纯水通量略有降低而牛血清白蛋白(BSA)截留率有所提高.随着接枝度的提高,PEGMA接枝改性膜的抗污染性能增加.     

可聚合纳米SiO2杂化材料的制备及其性能研究

利用异佛尔酮二异氰酸酯(IPDI)和纳米SiO2表面-OH基团反应的特点,制备了表面含-NCO基团的纳米SiO2,用端羟基聚丙二醇醚(PPG)对其扩链并进一步和丙烯酸羟乙酯(HEA)反应,制备了丙烯酸酯封端、IPDI和PPG连接纳米SiO2粒子的纳米SiO2杂化材料.用红外光谱(FTIR)、热失重(TGA)和扫描电镜(...     

双金属复合氧化物的结构与紫外阻隔性能

双金属复合氧化物（ＣＬＤＨ）是一类发展迅速的无机层状材料的煅烧产物,在催化、吸附等领域已获长足进展［１］,但作为紫外阻隔材料的性能研究尚鲜见报道．本文研究了不同双金属复合氧化物的紫外阻隔性能,结果发现二价金属离子为锌离子的ＣＬＤＨ具有良好的紫外阻隔性能．实验所用试剂均为分析纯．ＣＬＤＨ由ＮａＯＨ,Ｎａ２ＣＯ３,ＭｇＳＯ４·７Ｈ２Ｏ,ＺｎＳＯ４·７Ｈ２Ｏ,Ａｌ２（ＳＯ４）３·１８Ｈ２Ｏ为原料,按文献［２］方法制备．ＺｎＯ＋Ａｌ２Ｏ３复配物是按一定比例机械混合后,研磨,并在与ＣＬＤＨ相同的条件下煅烧…     

丙烯酸酯类单体在空气中紫外固化的研究

辐射可固化涂层在空气中进行紫外光照射，其固化速率随光引发剂组份的增加开始近似线性增大，到某一点后出现突跃．通过对氧气存在下的聚合机理的研究，认为上述现象与氧气引起的自由基终止以及固化过程中的氧气消耗速率有关．根据文中推导的关系式作出的示意图与实验数据基本吻合．     

pH响应木质素基胶体球的制备和表征

以造纸制浆废液中的松木碱木质素（AL）为原料,通过季铵化改性,制备了季铵化碱木质素（QAL）.QAL与十二烷基苯磺酸钠（SDBS）通过静电作用形成QAL/SDBS复配物,将QAL/SDBS复配物在乙醇/水混合溶剂中进行自组装得到具有pH响应性的胶体球.采用X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、元素分析和静态接触角研究了胶体球的形成过程和结构.研究结果表明,QAL/SDBS复配物通过疏水聚集作用形成具有较疏水的“核”和较亲水的“壳”结构的规整胶体球.在pH=3.0时,由于QAL与SDBS间的静电作用和疏水作用使胶体球能够稳定存在.当pH>7.5时,季铵化碱木质素上的羧基电离,由于静电斥力的作用使胶体球开始解聚,当pH=10.5时,季铵化碱木质素上的酚羟基的电离使得QAL与SDBS间的静电斥力增大,胶体球完全解聚.这种在酸性条件下稳定,中性条件下解聚的胶体球在药物缓释方面具有潜在的应用.     

紫外辐射诱导C60聚合的扫描隧道显微研究

C60的聚合反应是近年来C60研究的热点．Yeretzian等[1]首先在质谱中观察到了C60在激光作用下的聚合反应，我们也曾以激光真空溅射技术制备了丰富的C60与C70的聚合物[2]．进一步研究还发现，C60在紫外光照射下也能聚合成膜[3]．为更深入地了解C60的聚合过程，本文以扫描隧道显微（STM）技术跟踪观察了C60在紫外光辐射下所发生的形态变化．1实验部分C60吸附在Au（111）面上时能够铺展成单分子层[4]．因此，我们选择Au（111）面作基底，将C60配成一定浓度的甲苯溶液滴在金表面上，待甲苯挥发后制得C60的单分子层．实验所用的紫外光源为…     

离子液体/石墨烯复合光固化涂层的制备及性能研究

石墨烯在聚合物基体中分散不良是制约其应用的一个重要原因，尤其在石墨烯含量较高时，团聚不可避免。本文通过季铵化、亲核取代和阴离子置换反应，合成了双官光聚合离子液体单体。将其与石墨烯混合分散后，再和光固化环氧丙烯酸树脂6215-100复配，制备不同比例的复合涂层配方，并采用UV固化的方式在玻璃基材上成膜。利用衰减傅里叶全反射红外（ATR-FTIR）和核磁氢谱（¹HNMR）对可聚合离子液体单体进行结构表征，而复合配方的光聚合动力学、涂层的热性能和石墨烯的分散情况则通过实时红外（RTIR）、热重分析（TGA）和显微镜等手段进行表征。结果表明，光聚合离子液体对于石墨烯的分散具有良好的促进作用，涂层在1%和3%石墨烯含量的情况下表现出良好的热性能。     

新型锌铝水滑石紫外吸收剂的制备和紫外性能研究

以有机紫外吸收剂2-苯基苯并咪唑-5-磺酸(PBSA)、N,N-二甲氨基苯甲酸(DABA)为有机原料,采用共沉淀法,合成了有机紫外吸收剂插层水滑石Zn2Al-LDH/PBSA和Zn2Al-LDH/DABA,并测定了所得到的样品的XRD、FT IR、薄膜紫外吸收性质和氧化催化活性。结果表明,当有机紫外吸收剂以阴离子的形式进入水滑石层间后,仍有良好的紫外吸收性能并在可见光区有很好的透光性;通过测定插层水滑石的氧化催化活性,与纯有机物相比,Zn2Al-LDH/PBSA和Zn2Al-LDH/DABA的氧化催化活性明显降低。合成的新型的插层水滑石有望在防晒产品中得到应用。     

Novel approaches to flexible visible transparent hybrid films for ultraviolet protection

Herein, we present an overview of the most recent achievements and innovations regarding the development of flexible visible transparent films for selective ultraviolet (UV) shielding, with focus on those based on hybrid inorganic–organic materials. The main synthetic paths used nowadays to ensure a high degree of protection are reviewed. Polymers containing organic UV absorbing molecules, hybrid mixtures of polymers and nanoparticles, and the recently introduced series of structures displaying structural color, are identified as the three main types of materials used for this purpose. The use of biocompatible and flexible films to achieve spectrally selective UV protection can find applications in a wide diversity of fields such as photo‐treatment of skin diseases, food and beverage packing, and storage of cosmetics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

UV cured transparent films including non‐aqueous conductive microgels

UV cured transparent films containing non‐aqueous conductive microgels coated with poly(aniline)/dodecyl benzenesulfonic acid(DBSA) were obtained. The conductive microgels were prepared by interface polymerization of aniline/DBSA in the presence of non‐aqueous polymeric microgels. The electrical conductivity and the particle size of the prepared conductive microgel were 0.5 S/cm and 58 nm, respectively. The prepared conductive microgels were easily blended with a UV curable coating formulation, and then were cured to make highly optically transparent films. For the UV cured film containing about 35 wt% of the conductive microgels, a surface resistance in the range of 10⁷ to 10⁸ Ω/square was obtained. In a polar cosolvent, such as NMP and m‐cresol, the critical volume was shifted to the lower range, with a value of 10 wt%. The UV cured films containing the conductive microgels exhibited good electrical stability against the thermal aging and humidity. Copyright © 2002 John Wiley & Sons, Ltd.     

Transparent Polymer Opal Thin Films with Intense UV Structural Color

We report on shear-ordered polymer photonic crystals demonstrating intense structural color with a photonic bandgap at 270 nm. Our work examines this UV structural color, originating from a low refractive index contrast polymer composite system as a function of the viewing angle. We report extensive characterization of the angle-dependent nature of this color in the form of ‘scattering cones’, which showed strong reflectivity in the 275–315 nm range. The viewing range of the scattering was fully quantified for a number of planes and angles, and we additionally discuss the unique spectral anisotropy observed in these structures. Such films could serve as low-cost UV reflection coatings with applications in photovoltaics due to the fact of their non-photobleaching and robust mechanical behavior in addition to their favorable optical properties.     

Effects of UV irradiation on tribological properties of nano‐TiO2 thin films

One‐layer and two‐layer nano‐TiO₂ thin films were prepared on the surface of common glass by sol–gel processing. Water contact angle, surface morphology, tribological properties of the films before and after ultraviolet (UV) irradiation were investigated using DSA100 drop shape analyzer, scanning probe microscopy (SPM), SEM and universal micro‐materials tester (second generation) (UMT‐2MT) friction and wear tester, respectively. The stored films markedly resumed their hydrophilicity after UV irradiation. But UV irradiation worsened tribological properties of the films. After the film was irradiated by UV, the friction coefficient between the film and GCr15 steel ball increased about 10–50% and its wear life shortened about 20–90%. Abrasive wear, brittle break and adherence wear are the failure mechanisms of nano‐TiO₂ thin films. It was believed that UV irradiation increased surface energy of the film and then aggravated adherence wear of the film at initial stage of friction process leading to severe brittle fracture and abrasive wear. Copyright © 2009 John Wiley & Sons, Ltd.     

Studies on polymers and composites from lignin and fiber derived from sugar cane

Sugarcane fiber (i.e. bagasse) lignin has a larger fraction of aromatics unsubstitution in the ortho position than hardwood or softwood lignin and hence has the greater ability to be derivatized. Furthermore, organosolv lignin has a higher purity than sulfonated and kraft lignins. This work examines the purification of organosolv lignin derived from bagasse and the physico‐chemical properties of the lignin and lignin‐phenol formaldehyde (PF) resin coatings, and composites. The wetability tests have shown that lignin and lignin‐PF resin films are effective water barrier coatings, though the contact angles of lignin‐PF resin films were considerably less than the wax films. The overall mechanical properties (i.e. peak stress, peak strain and modulus) of the bagasse fiber composites were lower than the values obtained with the composites without the inclusion of bagasse fiber. Copyright © 2007 John Wiley & Sons, Ltd.     

Chemical vapour deposition of selenium and tellurium films by UV laser photolysis of selenophene and tellurophene

Excimer laser‐induced photolysis of gaseous selenophene and tellurophene affords gaseous 1‐buten‐3‐yne and ethyne (as major products) and butadiyne (a very minor product) and results in chemical vapour deposition of selenium and tellurium films. The film properties were characterized by XPS and SEM techniques and by UV spectroscopy. Copyright © 2000 John Wiley & Sons, Ltd.     

Cesium lead halide perovskite nanocrystals for ultraviolet and blue light blocking

Using cesium lead halide perovskite nanocrystals, CsPb(Cl/Br)_3, as a light absorber, we report a highly effective UV and blue light blocking film. The CsPb(Cl/Br)_3 nanocrystals are well dispersed in the ethyl cellulose(EC) matrix to compose a UV and blue light shielding film, and the absorption edge of the film is tunable by adjusting Cl to Br ratio using anion exchange. The CsPbCl_2 Br-EC film exhibits a transmittance of 5% at 459 nm, 90% at 478 nm and 95% in the range of 500–800 nm, which makes it excellent for UV and blue light shielding. In addition, the as-prepared EC-CsPb(Cl/Br)_3 film shows excellent photostability under UV irradiation. Results demonstrate that this EC-CsPb(Cl/Br)_3 based materials with sharp absorbance edges, tunable blocking wavelength, and high photostability can be useful for the applications in UV and blue light blocking and optical filters     

From cloudy to transparent: chain rearrangement in hydrogen-bonded layer-by-layer assembled films.

The cloudiness of hydrogen-bonded LBL films assembled from polyvinylpyrrolidone (PVPON) and poly(acrylic acid) (PAA) is studied in detail by two approaches: spectroscopy (Fabry-Pérot fringes) and microscopy (AFM). Fabrication parameters such as temperature, molecular weight, pH value, and rinsing time, have notable influences on film cloudiness. The buildup of the PVPON/ PAA film is a two-stage process of adsorption and chain rearrangement. Generally, adsorption is fast, while chain rearrangement is slow. The fast adsorption process traps defects, whereas the relatively slow chain-rearrangement process can not heal the defects in time; therefore; the number of defects continuously increases as LBL assembly proceeds, and a cloudy, heterogeneous film is produced. However, the as-prepared cloudy films become transparent and homogeneous on subsequent annealing in acidic water. UV/Vis spectroscopy and fluid AFM were applied to monitor this transition ex situ and in situ, respectively. It is found that increasing the annealing temperature accelerates the transition from cloudy to transparent, and the transition of the film made from higher molecular weight polymer is slower.     

Effect of the structural parameters of a series of fluoromonoacrylates on the surface properties of cured films

A series of fluorinated acrylates [F(CF₂)_q? (CH₂)_p? OCOCH?CH₂, where q = 8 and p = 2 ÷ 11) were synthesized and used as comonomers in the photopolymerization of acrylic systems. These fluoroacrylates were synthesized in a three‐step procedure through the radical addition of perfluoroalkyliodides to an unsaturated alcohol followed by their acrylation. The mixtures, containing up to 0.8% (w/w) of the comonomers, produced transparent films after UV curing; they showed changes in the surface properties as a function of the comonomer type and concentration. With contact‐angle and X‐ray photoelectron spectroscopy analyses, the relationship between the structure of the monomers and the surface properties of the UV‐cured films was investigated: the wettability decreased, depending on the length of the fluorinated group (q value) and the hydrogenated segment of the monomer (p value). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4227–4235, 2001     

Stable PZT sol for preparing reproducible high-permittivity perovskite-based thin films

Results are reported on the development of high-K dielectric material using sol-gel chemistry. High permittivity thin film capacitor have been developed based on lead-zirconate-titanate (PbZr _x Ti_1−x O₃, PZT) ferroelectric ceramic layers deposited on to 6″ platinized silicon wafer using the spin-coating technique. Selecting a diol-based solvent as diluting medium, a PZT solution with remarkable shelf life up to 1 year has been prepared. To synthesize such a reproducible and time-stable solution, a ripening step before dilution has been introduced. The deposition process has been also optimized to reduce the required number of coatings and to avoid intermediate high-temperature annealing. By carefully controlling environmental parameters, the as-developed PZT solution leads to reproducible high-performance thin film capacitor, enabling an industrial use. Thus, 200-nm thick PZT layers with permittivity as high as 900, capacitance as high as 40 nF/mm2 and breakdown voltage up to 30 V have been obtained.