半连续和间歇式丙烯酸酯三元乳液共聚产物的形态及分子结构研究

研究了半连续和间歇式丙烯酸酯三元乳液共聚产物的形态和分子结构。结果表明,半连续式胶乳粒子呈“多核核壳结构”,其粒径和粒径分布随单体滴加速度减慢而变小。间歇式胶乳粒径较大,粒径分布亦更宽,呈硬相在外的“单核核壳结构”;共聚物分子链中VAc结构单元的序列较长。两种方法所获无规共聚物均存在微相分离结构,分离程度随单体滴加速度的加快而变大。     

离子型共聚单体用于高固含量无皂乳液聚合的研究——甲基丙烯酸异丁酯/甲基丙烯酸甲酯/丙烯酸丁酯无皂乳液聚合体系

该文采用自行合成的一种带亲水性磺酸离子基团及羟基的可共聚单体 3 烯丙氧基 2 羟基丙磺酸钠(AHPS)用于甲基丙烯酸异丁酯 /甲基丙烯酸甲酯 /丙烯酸丁酯 (IBMA/MMA/BA)无皂乳液聚合体系 .对乳胶粒粒径大小、乳液流体力学行为、共聚物的动态力学性质、拉伸行为及耐水性进行了研究 ,并对乳胶粒的成核机理进行了探讨 .实验结果表明 ,带亲水性离子基团可共聚单体AHPS的加入可获得 0 6μm左右的乳胶粒 ,乳液固含量可达 60 % ,表现粘度测定结果表明乳液呈Bingham流体 .三元共聚物在动态粘弹谱图上只出现单一的玻璃化转变温度峰 ,是完全的无规共聚物 ,拉伸强度明显大于常规乳液聚合方法得到的聚合物 ,耐水性也得到显著提高 .     

Effect of the silica content on the physico-chemical and relaxation properties of hybrid polymer/silica nanocomposites of P(EMA-co-HEA)

Poly(ethyl methacrylate-co-hydroxyethyl acrylate) 70/30 %wt/silica, P(EMA-co-HEA)/SiO₂, nanocomposites, with silica contents ranging from 0 to 30 %wt, were synthesized and studied as promising candidate materials for the synthetic matrix of scaffolds for bone substitutes or dentin regeneration. The physico-chemical properties of the hybrids were studied by calorimetry and by contact angle measurements on the surfaces. The dynamic-mechanical and compression properties were analysed. Intermediate silica contents in the range from 10 to 20 %wt of silica rendered co-continuous interpenetrated structures, in which silica produced a reinforcing effect in the polymeric matrix and at the same time conferred bioactivity to the surfaces by improving surface wettability, making these hybrids appropriate for the proposed application. On the contrary, silica percentages below 10 %wt formed disconnected inorganic aggregates at the nanoscale dispersed in the copolymer matrix, which did not modify significantly the copolymer properties. Silica contents above 20 %wt formed denser inorganic networks with few terminal silanol groups available at the surfaces, much more rigid and hardly manageable samples.     

Palladium(0)-catalyzed rearrangement of allyl enol ethers to form chiral quaternary carbon centers via asymmetric allylic alkylation

Herein we report the first palladium(0)-catalyzed asymmetric allylic alkylation (AAA) of allyl enol ether via π-allylpalladium intermediate using Trost chiral diphosphine. This unprecedented reaction produced very rare α-aryl quaternary aldehydes with multi-functional groups. The main novelty in the chemistry demonstrates that enol ethers can be used as precursors for π-allylpalladium intermediates, an observation that is certainly rare and to the best of our knowledge, perhaps without prior precedent. Chiral ligand (R,R)-L3 was found to be optimal in this Pd-AAA reaction and provided good to excellent yield (80–95%) and enantioselectivity (70–90%) with a range of analogs.     

Color Stabilization of Polyvinyl Chloride) with Heat Treatment

Stabilization of polyvinyl chloride) (PVC) containing metal soaps was investigated by psychophysical colorimetry. A color difference observed among heated PVC films containing various metal salts depends on coloration of the π-complex of polyene with metal chloride converted from the metal salt added and that the stabilization effect of synergistic soaps should be based on an effect of complementary colors set up among a polyene color and metal chloride-polyene complex colors. These conclusions are well supported by colorimetry of heated PVC films containing various dyes. The color of heated PVC films containing Zn/Ca and Cd/Ba synergetic soaps markedly deviated from a polyene color with increased heat treatments, owing to greater degree of coloration of Zn complex and Cd complex, respectively. These color deviations usually decrease the thermal stability of PVC. The thermal stability of PVC was markedly improved by the use of synergetic soaps together with masking agent such as triethanolamine, urea, N,N′-dimethylol-urea, and vinylpyridine-methylmethacrylate copolymer, owing to the masking effect of these nitrogen-containing compounds. These masking agents did not slow down the dehydrochlorination of PVC.     

INVESTIGATION OF THE USE OF POLY(3,4-EPOXY-1-BUTENE) IN FREE RADICAL PHOTOPOLYMERIZATIONS

ABSTRACT

The use of poly(3,4-epoxy-1-butene) (polyEPB) in photoinduced free radical polymerizations has been investigated. It was observed that the inclusion of polyEPB into these photopolymerizations has several beneficial effects. In combination with aromatic ketones, polyEPB functions as a hydrogen donor to form a highly effective photoinitiator for the polymerization of acrylate monomers. At the same time, polyEPB undergoes facile autoxidation that serves to mitigate inhibition effects due to oxygen during free radical photopolymerizations. PolyEPB is an effective chain transfer agent that tends to increase both the rate and conversion in photoinduced crosslinking polymerizations in which multifunctional monomers are employed. Lastly, polyEPB is a interesting matrix-modifying agent that becomes incorporated into the resin matrix during photopolymerization due to photoinduced grafting reactions.     

Synthesis and Characterization of Antimony (V)-Polycobalticinium Esters

Antimony (V) polycobalticinium esters, where the anion was PF₆ ^?, Cl^?, Br^? and NO₃ ^?, were synthesized. A number of factors were found to be important in the synthesis, including anion exchange and pH. The products containing PF₆ ^? are oligomeric (DP _w = 7) whereas the other products are di-and trimeric. The products undergo oxidative degradation beginning about 100 to 225°C. They are near semiconductors with resistivities about 10⁵ to 10⁷ ohm-cm.     

多元丙烯酸酯泡沫制备中的溶剂效应

 以季戊四醇四丙烯酸酯（PETA）为聚合单体，安息香乙醚为引发剂，通过紫外光引发生成凝胶，通过真空干燥得到PETA泡沫材料。通过理论计算和实验确定的多元丙烯酸酯交联聚合物的溶解度参数值为19.0左右，含有苯环的脂肪烃和酮类的溶剂会导致引发剂“失活”，而卤代烃、酯、醚和酰胺类溶剂能够保持引发剂的“活性”。     

碳纳米管/丙烯酸酯涂料的制备及其红外吸波性能

"利用表面改性剂对碳纳米管进行表面改性来防止其颗粒的团聚,从而制得分散性较好的碳纳米管浆料,在此基础上来制备碳纳米管/丙烯酸酯涂料,并研究了它在近红外波段的反射率．分析了PVC浓度、表面改性剂的种类及浓度以及碳纳米管的管长,对碳纳米管/丙烯酸酯涂料在?=930 nm处反射率的影响,并对涂料工艺进行了优化设计,最终制备出了吸收性能优良的碳纳米管/丙烯酸酯涂料．它在840~950 nm的近红外波段的反射率为均在0.1%以下并且透射率均在1.0%以下．"