1,3,5-三甲基-1,3,5-三(3′,3′,3′-三氟丙基)环三硅氧烷的阴离子开环(共)聚合研究进展

1,3,5-三甲基-1,3,5-三(3′,3′,3′-三氟丙基)环三硅氧烷(F3)的阴离子开环聚合可以合成优越耐油耐溶剂性能的聚甲基三氟丙基硅氧烷(PMTFPS),但在开环聚合过程中“反咬”与再分布副反应严重,要得到高分子量、高产率的氟硅聚合物材料,必须严格控制聚合反应条件。文中总结了本体、溶液、细乳液中F3的阴离子开环聚合影响因素、机理与动力学,以及F3与其它单体共聚合反应等方面的研究进展。     

高活性TiO2纳米晶的酸催化Sol-Gel法制备与表征

采用酸催化的溶胶-凝胶法制备出了纳米TiO2光催化剂，以甲基橙的光催化降解为探针反应，评价了其光催化活性．运用XRD、TEM、FT—IR以及PL光谱技术对纳米TiO2的微晶尺寸、晶体结构、表面组成和性能进行表征．结果表明，400℃焙烧的TiO2纳米粒子的颗粒形貌为近球形，晶粒尺寸为11．69 nm，样品分散性良好的锐钛矿型结构．在光催化降解甲基橙的实验中，400℃焙烧的TiO2纳米粒子表现出最高的光催化活性，这与表征结果一致．此外，550℃和650℃焙烧的具有锐钛矿型和金红石型混晶结构的TiO2纳米粒子，无混晶协同促进效应．     

氯化聚乙烯对氯丁橡胶与甲基丙烯酸甲酯接枝共聚反应的影响

研究了高氯氯化聚乙烯(HCPE)对氯丁橡胶与甲基丙烯酸甲酯接枝共聚及其反应产物的影响。结果表明,HCPE能加快聚合速率,提高转化率、接枝效率和接枝度。含HCPE的产物,含有较高分子量的级份,分子量分布较宽,树脂相的分布比较均匀,并具有较好的机械性能和较高的粘接强度。     

PU／P（MA—DMA）／EP三组分IPN力学性能的研究

用同步法合成聚氨酯/聚(丙烯酸甲酯-甲基丙烯酸β-N,N′-2-甲基乙酯)/环氧树脂三组分互穿聚合物网络,对IPN组成、结构与性能的关系进行了讨论。结果表明,改变组成比可以得到相容性不同的IPN。本文认为组成比对IPN性能的影响较连续相为大,加入接枝剂可以有效地改变IPN的相容性。力学性能与组成网络的结构及缠结方式有关,组成比相同时,全IPN具有较大的应力值。加入填料,体系中发生“准交联”作用,使阻尼值增高,转变温度区域加宽。     

甲基丙烯酸甲酯/甲基丙烯酸丁酯/苯乙烯超浓乳液聚合及动力学研究

以十二烷基硫酸钠(SDS)和十六醇(HD)为复合乳化体系,偶氮二异丁腈(AIBN)为引发剂,甲基丙烯酸甲酯(MMA)／甲基丙烯酸丁酯(BMA)／苯乙烯(St)为混合单体,在40℃～45℃引发聚合,制备了分散相占85％以上的稳定超浓乳液．探讨了引发剂种类、浓度,复合乳化剂配比、浓度,聚合温度等因素对乳液稳定性和聚合速率的影响。建立了该聚合反应的动力学方程。     

阴离子本体开环聚合反应挤出合成聚三氟丙基甲基硅氧烷

以同向紧啮合双螺杆挤出机为反应器,硅醇钠/乙酸乙酯(EA)为引发体系,通过三氟丙基甲基环三硅氧烷(F3)阴离子本体开环聚合,制备了聚三氟丙基甲基硅氧烷(PMTFPS)。采用红外光谱(FT-IR),核磁共振(1H-NMR)和凝胶渗透色谱(GPC)确认了聚合物的结构与分子量,用电离飞行时间质谱分析了副产物的组成。研究表明,提高反应温度和EA用量可使反应平衡点提前到达。而螺杆转速对反应的主要影响在于改变聚合反应时间。因此,控制适当反应条件,使反应在平衡点到来时间之前终止,可得到高分子量以及高收率的PMTFPS。所得产物的数均分子量为2.41×105,分子量分散指数为1.12,产率为90.5%。     

ILB®, a Low Molecular Weight Dextran Sulphate,Restores Glutamate Homeostasis,Amino Acid Metabolism and Neurocognitive Functions in a Rat Model of Severe Traumatic Brain Injury

In a previous study, we found that administration of ILB^®, a new low molecular weight dextran sulphate, significantly improved mitochondrial functions and energy metabolism, as well as decreased oxidative/nitrosative stress, of brain tissue of rats exposed to severe traumatic brain injury (sTBI), induced by the closed-head weight-drop model of diffused TBI. Using aliquots of deproteinized brain tissue of the same animals of this former study, we here determined the concentrations of 24 amino acids of control rats, untreated sTBI rats (sacrificed at 2 and 7 days post-injury) and sTBI rats receiving a subcutaneous ILB^® administration (at the dose levels of 1, 5 and 15 mg/kg b.w.) 30 min post-impact (sacrificed at 2 and 7 days post-injury). Additionally, in a different set of experiments, new groups of control rats, untreated sTBI rats and ILB^®-treated rats (administered 30 min after sTBI at the dose levels of 1 or 5 mg/kg b.w.) were studied for their neurocognitive functions (anxiety, locomotor capacities, short- and long-term memory) at 7 days after the induction of sTBI. Compared to untreated sTBI animals, ILB^® significantly decreased whole brain glutamate (normalizing the glutamate/glutamine ratio), glycine, serine and γ-aminobutyric acid. Furthermore, ILB^® administration restored arginine metabolism (preventing nitrosative stress), levels of amino acids involved in methylation reactions (methionine, L-cystathionine, S-adenosylhomocysteine), and N-acetylaspartate homeostasis. The macroscopic evidences of the beneficial effects on brain metabolism induced by ILB^® were the relevant improvement in neurocognitive functions of the group of animals treated with ILB^® 5 mg/kg b.w., compared to the marked cognitive decline measured in untreated sTBI animals. These results demonstrate that ILB^® administration 30 min after sTBI prevents glutamate excitotoxicity and normalizes levels of amino acids involved in crucial brain metabolic functions. The ameliorations of amino acid metabolism, mitochondrial functions and energy metabolism in ILB^®-treated rats exposed to sTBI produced significant improvement in neurocognitive functions, reinforcing the concept that ILB^® is a new effective therapeutic tool for the treatment of sTBI, worth being tested in the clinical setting.     

Novel Epoxides of Soloxolone Methyl: An Effect of the Formation of Oxirane Ring and Stereoisomerism on Cytotoxic Profile,Anti-Metastatic and Anti-Inflammatory Activities In Vitro and In Vivo

It is known that epoxide-bearing compounds display pronounced pharmacological activities, and the epoxidation of natural metabolites can be a promising strategy to improve their bioactivity. Here, we report the design, synthesis and evaluation of biological properties of αO-SM and βO-SM, novel epoxides of soloxolone methyl (SM), a cyanoenone-bearing derivative of 18βH-glycyrrhetinic acid. We demonstrated that the replacement of a double-bound within the cyanoenone pharmacophore group of SM with α- and β-epoxide moieties did not abrogate the high antitumor and anti-inflammatory potentials of the triterpenoid. It was found that novel SM epoxides induced the death of tumor cells at low micromolar concentrations (IC₅₀^(24h) = 0.7–4.1 µM) via the induction of mitochondrial-mediated apoptosis, reinforced intracellular accumulation of doxorubicin in B16 melanoma cells, probably by direct interaction with key drug efflux pumps (P-glycoprotein, MRP1, MXR1), and the suppressed pro-metastatic phenotype of B16 cells, effectively inhibiting their metastasis in a murine model. Moreover, αO-SM and βO-SM hampered macrophage functionality in vitro (motility, NO production) and significantly suppressed carrageenan-induced peritonitis in vivo. Furthermore, the effect of the stereoisomerism of SM epoxides on the mentioned bioactivities and toxic profiles of these compounds in vivo were evaluated. Considering the comparable antitumor and anti-inflammatory effects of SM epoxides with SM and reference drugs (dacarbazine, dexamethasone), αO-SM and βO-SM can be considered novel promising antitumor and anti-inflammatory drug candidates.     

MAA/SAS共聚物陶瓷粉体分散剂的制备及表征

以甲基丙烯酸(MAA)和烯丙基磺酸钠(SAS)为单体,制得MAA/SAS共聚物。探讨了不同反应条件对共聚物分散性的影响,通过FT-IR、GPC及TGA-DSC等手段对共聚物的结构、热稳定性以及相对分子质量及其分布进行了表征。并对最佳条件下制得的共聚物分散剂在陶瓷氧化铝浆料中进行分散效果试验,结果表明,当共聚物加入量为0.5%时,分散效果良好。     

元素碘参与的甲基丙烯酸甲酯衰减链转移聚合

90℃进行元素碘参与的甲基丙烯酸甲酯(MMA)衰减链转移聚合,发现其诱导期明显缩短,聚合速度加快,Mw/Mn与70℃～80℃没有明显差别.[MMA]0:[AIBN]0:[I2]0=1140:1.0:0.8时,动力学表明聚合仍具明显活性.表明普通聚合体系加少量元素碘,即可转为活性聚合.1H-NMR表明,90℃聚合时,聚合物分子结构发生变化,产生了一种新的次甲基,合理解释为Pn-I高温均裂,引发分子内重排再引发,聚合机理与70℃～80℃有所区别.