腰果酚的紫外光固化机理和固化膜性能

研究了腰果酚在无光引发剂条件下的紫外光固化反应,并用IR、UV、元素分析、GPC等分析手段分析了腰果酚的紫外光固化机理及其固化膜性能。结果表明:在紫外光辐照下,腰果酚通过侧链发生氧化聚合反应,和酚羟基的邻对位失去质子形成的自由基引起的苯环缩合反应,最终形成体型高聚物。腰果酚的紫外光固化膜的常规物理机械性能、抗溶剂性、耐化学介质腐蚀性、热稳定性和抗紫外线性能均优于腰果酚醛缩聚物(PC)涂膜。     

类米氏酮光引发剂的合成及在ATRP中的应用

以4,4’-二甲基二苯甲酮为原料,经过溴化、选择性胺化、O-烷基化等反应,依次合成了4-(溴甲基)-4’-[双(羟乙基)氨基]二苯甲酮与4-(腰果酚基甲基)-4’-[双(羟乙基)氨基]二苯甲酮两个功能性的类米氏酮光引发剂,收率分别为58%和46%。在4-(溴甲基)-4’-[双(羟乙基)氨基]二苯甲酮中含有苄溴基团,因此该化合物还可作为ATRP或SET-LRP引发剂。同时,利用4-(溴甲基)-4’-[双(羟乙基)氨基]二苯甲酮作引发剂进行了腰果酚单体的AGET ATRP聚合反应,得到相应的腰果酚均聚物(Mn=20.2 k Da,PDI=1.11)。小分子化合物的结构用1H-NMR进行了表征。     

二苯甲酮／胺：紫外光固化涂料中的新型引发剂

通过三羟甲基丙烷三丙烯酸酯与二乙胺的迈克尔加成反应,合成了一种新型叔胺衍生物,利用＾１Ｈ ＮＭＲ对其进行了验证。当该叔胺与二苯甲酮配合使用时,表现出很好的固化速度并能代替昂贵的光引发剂１１７３,使紫外光固化涂料的成本显著降低。同时,对该二苯安双分子引发剂的作用机理进行了探讨。     

酚醛胺复合固化高渗透弹性环氧浆液

将腰果酚、三乙烯四胺和多聚甲醛(CH2O单元计算)按照摩尔比为1∶1∶1在110~120℃下通过Mannich反应制备了含长链烷基的腰果酚酚醛胺,研究了腰果酚酚醛胺与酚醛叔胺2,4,6-三(二甲胺基甲基)苯酚的酚铵复合后催化固化以糠醛丙酮为活性稀释剂的AB双组分环氧浆液的固化机理及固结体的力学性能。结果表明,酚铵盐与腰果酚酚醛胺复合物具有良好的催化糠醛与丙酮的醇醛缩合、环氧树脂的开环聚合固化。当A组分中环氧含量在30%~40%(wt)、A/B=100∶10~20、酚铵盐在B组分中占20%(wt)时,浆液具有较低的起始粘度高渗透性及较快的固化,净浆和水泥基浆液固体体强度高,韧性大,压缩应变分别高达18%、9%。     

紫外光固化水性油墨及墨膜耐磨性能

传统紫外光固化(UV)油墨具有粘度低、固化速度快、应用范围广等优点。 但存在使用少量有机溶剂、交联程度低等缺陷。 本文通过自由基聚合制备的苯乙烯丙烯酸共聚物与甲基丙烯酸羟乙酯(HEMA)反应制备水性预聚物。 通过甲基丙烯酸缩水甘油酯(GMA)和乙二胺反应制备了含有四丙烯酸官能团的活性稀释剂。 最后,通过水性预聚物、活性稀释剂、光引发剂以及少量溶剂制备了UV光固化水性油墨。 探讨了光引发剂的种类和质量分数、预聚物的相对分子质量和质量分数、活性稀释剂的结构和质量分数对UV油墨的光固化速度以及耐磨度的影响。 当预聚物的数均相对分子质量为1.98×10⁵且质量分数为30%、光引发剂质量分数为4%、活性稀释剂的官能团数目为4且质量分数为40%的UV水性油墨的光固化速率为1 s,经50次磨损质量损失为9%。 该方法所制得的UV水性油墨可用于柔版印刷、凹印、数字印刷等。     

一种新型二苯甲酮类光引发剂的合成及其性能研究

本文先以4-甲基二苯甲酮合成4-(溴甲基)二苯甲酮,然后用4-羟基二苯甲酮和4-(溴甲基)二苯甲酮为原材料合成了一种含二苯甲酮结构的新型光引发剂(MBPBP)。通过核磁共振氢谱图确定了其结构;利用紫外吸收谱图研究了其紫外吸收和光降解性能;最后通过RT-FTIR分析了光引发剂浓度、光照强度和反应单体对光聚合反应的影响。结果表明,MBPBP的摩尔消光系数约为二苯甲酮的1.5倍,吸收范围大大增加,延伸到300nm,吸光效率获得大幅提高,光引发活性远大于传统的二苯甲酮,是一种高效光引发剂。     

4-氯苯基二苯基硫六氟磷酸盐的合成

与自由基型UV光固化体系相比,近年来开发的阳离子型UV光固化体系具有以下优点:(1)固化收缩率小;(2)不被氧气所阻聚;(3)厚膜固化;(4)低毒性[1]。该体系的重要组分阳离子光引发剂有很多种类,其中三芳基硫鎓盐又有其独特的优点,它能溶于绝大多数阳离子聚合的单体中[2]。虽然其引发     

过氧化尿素法快速合成具有光引发活性的ATRP引发剂

以过氧化尿素和氢溴酸为溴化试剂,分别对4-甲基二苯甲酮和4,4'-二甲基二苯甲酮进行选择性溴化,合成了两个具有光引发活性的原子转移自由基聚合(ATRP)引发剂-4-溴甲基二苯甲酮和4,4,-二(溴甲基)二苯甲酮,产率分别为91%和46%,其结构经NMR,IR和元素分析确认.     

{4-[4-（对硝基苯甲酰基）苯硫基]苯}苯基碘鎓六氟磷酸盐的合成与光引发性能测试

紫外光固化反应按机理分为自由基固化、阳离子固化以及自由基-阳离子混杂固化.自由基-阳离子混杂固化是指在同一体系里同时通过自由基聚合和阳离子聚合而发生的固化[1].混杂聚合结合了各个聚合反应的优点,表现出很好的协同效应.杂化光引发剂被设计成既能引发自由基聚合又能引发阳离子聚合的光引发剂.据报道,目前常见的杂化光引发剂主要有碘鎓盐类和苯基膦二苯甲酮类[2].     

新型光引发剂体系及其应用

紫外光固化技术具有环保、节能、可控等优点而广泛地应用于涂料、油墨、微电子和生物材料的领域,在紫外光固化技术光引发剂体系中起着十分关键的作用,新型高性能光引发剂的研制与开发广受科研工作者的重视,同时光引发剂因其独特的优点而不断的应用到一些新兴的科学领域中。本文介绍了作者课题组近5年来在新型高分子光引发剂方面的研究工作,这些工作主要围绕新型高分子硫杂蒽酮光引发剂、高分子二苯甲酮光引发剂和两亲性高分子光引发剂等三个方面展开,同时还介绍了这些新型的高分子光引发剂体系在微纳米粒子和聚合物刷等方面的应用。     

Synthesis of cardanol-based photo-active SET-LRP initiator and its application to preparation of UV-cured resin

A benzophenone-containing SET-LRP initiator based on renewable and abundant cardanol was synthesised in 71 % yield using the selective etherification reaction. Next, methyl methacrylate (MMA) as a monomer was polymerised under SET-LRP conditions using the newly prepared initiator to prepare cardanol-end poly(methyl methacrylate) (PMMA). The kinetic results of the polymerisation indicated that the reaction was controllable when the monomer conversion was lower than approximately 50 %, and the molecular masses of PMMA measured by GPC were higher than the theoretical values while the monomer conversion was more than 50 %. In addition, most of the carbon-carbon double bonds of the side hydrocarbon chain of the end-cardanol group in the PMMA were kept intact from ¹H NMR spectrum characterisation. Accordingly, when the cardanol-end PMMA together with a tertiary amine-containing cardanol derivative was irradiated by UV light, the corresponding UV-cured resin was obtained. The chemical resistance and hardness of the UV-cured film were enhanced with the increasing irradiation time.     

Photoaddition of ketones to imidazoles,thiazoles, isothiazoles and isoxazoles. Synthesis of their oxetanes

Imidazole itself did not undergo photoaddition reactions with ketones. However, irradiation of 1-acetyl and 1-benzoylimidazole, and 1,1-carbonyldiimidazole with benzophenone yielded oxetanes. On irradiation with carbonyl compounds, 1,2-dimethylimidazole and 1-benzylimidazole did not give oxetanes but a hydroxyaryl or hydroxyalkyl derivative. Thiazole itself did not yield any photoaddition product, but 2,4-dimethylthiazole afforded oxetanes on irradiation with benzophenone and with 3-benzoylpyridine. Irradiation of 2,4-dimethylthiazole with acetophenone led to the formation of a dimeric material. On irradiation with benzophenone, 4-methylisothiazole did not yield an oxetane but rather a hydroxyphenyl derivative. 3,5-Dimethylisoxazole on irradiation with benzophenone and with 3-benzoylpyridine gave oxetanes. Irradiation of 4,5-dimethylisoxazole yielded similarly an oxetane with benzophenone     

Selective Photoinduced Oxidation of Benzylic Methylen Groups through UV Irradiation in Presence of Ferric Chloride

Selective oxidation of benzylic methylene groups through UV irradiation in acetone/water/FeCl₃ mixtures is reported. This method applied to a series of model compounds, provides an easy access to the corresponding 1-oxo derivative. Thus, tetralin gives a 100% yield of 1-tetralone, indane leads to 60% of 1-indanone, and diphenylmethane is oxidized to benzophenone with 80% yield. However, under the same conditions, alkyl-substituted aromatic hydrocarbons such as toluene, ethyl- and propylbenzene lead to low yields of aldehydes or ketones. Isochromane furnishes a mixture of two substances which can be interconverted, namely the expected l-isochromanone (9%) and the corresponding hydroxy acid (23%). We failed to apply the method to nitrogen heterocycles containing benzylic groups such as 1,2,3,4- and 5,6,7,8-tetrahydroquinoline as they do not react due to the formation of complexes which precipitate from the solutions.     

Photopolymerization and toughening performance in polypropylene of hyperbranched polyurethane acrylate

A novel UV-curable hyperbranched polyurethane acrylate (HUA) was synthesized and found to polymerize rapidly in the presence of 5 wt.% benzophenone in N₂ under UV exposure. The photopolymerization kinetics of HUA was studied by differential photocalorimetry (DPC). Its toughening effect for polypropylene (PP) was investigated by tensile and impact tests of the UV irradiated PP/HUA blends. The morphological structures and thermal behavior were determined by polarized optical microscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The obtained results demonstrate that (1) the maximum photopolymerization rate increases with raising temperature up to 140 °C, whereas decreases at above 150 °C. The activation energy of 19 kJ mol⁻¹ for the photopolymerization was obtained at below 140 °C from the Arrhenius plot, while it is negative at above 150 °C. (2) The incorporation of 5 wt.% HUA greatly improved the notched impact strength of PP matrix with a slight improvement in the tensile strength and without obvious decline in breaking elongation. These results correlate well with SEM observation. (3) During the UV irradiation of PP/HUA blends, PP can be crosslinked/grafted with the cured HUA particles, resulting in the increase of the impact strength of PP matrix. (4) The cured HUA particles in the PP/HUA blends act as heterogeneous nucleation agent for PP, which results in the decrease of spherulite size and less perfection of PP crystals.     

Renewable epoxidized cardanol‐based acrylate as a reactive diluent for UV‐curable resins

A novel kind of biobased monomer, epoxidized cardanol‐based acrylate (ECA), was successfully synthesized from cardanol via acrylation and epoxidization. The chemical structure was confirmed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. Then, the ECA was employed to produce UV‐curable films and coatings copolymerized with castor oil‐based polyurethane acrylate. Compared to coatings from petroleum‐based diluent hydroxyethyl acrylate‐based castor oil‐based polyurethane acrylate resins, ECA‐based biomaterials exhibited a little inferior dilution ability but overcome the drawback of high volumetric shrinkage with a special lower value. Moreover, ultimate properties of the UV‐cured biomaterials such as thermal, mechanical, coating, swelling, and hydrophobic properties were investigated. The UV‐curing behavior was investigated using real‐time IR, and the overall double bond conversion was more than 90%. This biobased UV‐curable cardanol‐based diluent shows a promise in “green + green” materials technologies.     

Benzophenone derivatives as novel organosoluble visible light Type II photoinitiators for UV and LED photoinitiating systems

Five organosoluble visible light benzophenone derivatives ( BPs ), incorporated different arylamine as electron donating groups have been synthesized and investigated for their roles as photoinitiating systems for free radical photopolymerization of acrylate monomer upon the UV and LED exposure. All the target compounds ( BP-1 – 5 ) have confirmed through ¹H NMR, HR-MS/EI-MS spectra and elemental analysis. BPs displayed red-shifted absorption, higher molar extinction coefficient and better thermal properties as compared to reference benzophenone (BP) compound. BP and BPs in combination with hydrogen donor, triethylamine (TEA), are prepared and investigated their electron spin resonance (ESR) spectroscopy and photo-DSC (photo-differential scanning calorimetry). ESR spectra of BP-1 /TEA package showed the highest radical intensity among the test photoinitiator packages. In addition, BP-1- based formulation exhibited the best double bond conversion efficiency than other BPs and comparable to the BP for the free radical polymerization (FRP) of TMPTA under similar UV light source. We then selected BP-1 /TEA and BP/TEA package for FRP under LED light irradiation. Interesting, the BP-1 /TEA system exhibited better efficiency and shorter time at maximum heat flow than BP/TEA. This result indicates BP-1 photoinitiator not only displays good light harvesting, thermal property, but exhibits conversion efficiency under the irradiation of UV and LED.     

Photo-grafting Poly(acrylic acid) onto Poly(lactic acid) Chains in Solution

Poly(lactic acid)(PLA)is one of the most important bio-plastics,and chemical modification of the already-polymerized poly(lactic acid)chains may enable optimization of its material properties and expand its application areas.In this study,we demonstrated that poly(lactic acid)can be readily dissolved in acrylic acid at room temperature,and acrylic acid can be graft-polymerized onto poly(lactic acid)chains in solution with the help of photoinitiator benzophenone under 254 nm ultraviolet(UV)irradiation.Similar photo-grafting polymerization of acrylic acid(PAA)has only been studied before in the surface modification of polymer films.The graft ratio could be controlled by various reaction parameters,including irradiation time,benzophenone content,and monomer/polymer ratios.This photo-grafting reaction resulted in high graft ratio(graft ratio PAA/PLA up to 180%)without formation of homopolymers of acrylic acid.When the PAA/PLA graft ratio was higher than 100%,the resulting PLA-g-PAA polymer was found dispersible in water.The pros and cons of the photo-grafting reaction were also discussed.     

Synthesis and photochemical reactivity towards the Paternó–Büchi reaction of benzo[b]furan derivatives: their use in the preparation of 3-benzofurylmethanol derivatives

4-Amino-2,7-dimethylbenzo[b]furan and 4-chlorobenzo[b]furan have been synthesized. The irradiation of 4-amino-2,7-dimethylbenzo[b]furan in the presence of benzaldehyde gave the corresponding endo adduct. The adduct can be hydrolysed to the corresponding 3-benzofurylmethanol derivative. The irradiation of the same compound in the presence of benzophenone gave the corresponding adduct. 4-Chlorobenzo[b]furan did not react with benzaldehyde while, in the presence of benzophenone, gave the corresponding adduct. The hydrolysis of this adduct gave the corresponding 3-benzofurylmethanol derivative.