聚醋酸乙烯酯的可逆加成断裂链转移溶液聚合

以二硫化二异丙基黄原酸酯(DIP)为链转移剂前驱体,偶氮二异丁腈(AIBN)为引发剂,采用可逆加成断裂链转移(RAFT)溶液聚合合成了低数均分子量(M_n < 1.0×10⁴)和窄分子量分布(M_w/M_n < 1.5)的聚醋酸乙烯酯(PVAc)。用核磁共振(¹H-NMR)、凝胶渗透色谱(GPC)表征了PVAc的结构与分子量。结果表明:溶剂类型、引发剂浓度、链转移剂浓度和聚合反应温度对醋酸乙烯酯RAFT自由基聚合的转化率及可控/"活性"特征有重要影响。在相同条件下,溶剂极性较大的四氢呋喃对PVAc的分子量及其分布的可控性要优于极性较小的苯溶剂;聚合速率及产物分子量分布均随着引发剂浓度的增加而增大;增大DIP的浓度,聚合速率降低,聚合过程的可控性变好;温度升高聚合速率加快,分子量分布指数(PDI)增大。     

Xanthate‐Mediated Controlled Radical Polymerization of N‐Vinylcarbazole

Summary: Well‐defined poly(N‐vinylcarbazole) [poly(NVC)] was synthesized by macromolecular design via interchange of the xanthates (MADIX)/reversible addition‐fragmentation chain transfer (RAFT) polymerization. The homopolymers with controlled molecular weights ( = 3 000–48 000) and low polydispersities indices ( = 1.15–1.20) were obtained by the polymerization of NVC with AIBN in the presence of O‐ethyl‐S‐(1‐phenylethyl) dithiocarbonate as a xanthate‐type chain transfer agent (CTA). Good control of the polymerization was confirmed by the linear first‐order kinetic plot, the molecular weight controlled by the monomer/CTA molar ratio, linear increase in the molecular weight with the conversion, and the ability to extend the chains by the second addition of the monomer.

Radical polymerization of NVC in the presence of CTA and plot of number‐average molecular weight (circles) and polydispersity (squares) as a function of conversion.     

伤科黄药治疗早期胫腓骨骨折70例

目的:观察伤科黄药治疗早期胫腓骨骨折的临床疗效。方法:将140例患者随机分为对照组和治疗组,每组各70例。对照组给予常规治疗,治疗组在对照组的基础上给予伤科黄药外敷治疗,观察两组患者的疼痛疗效及肿胀消退疗效。结果:疼痛疗效:治疗组有效率为63%,对照组有效率为44%,两组比较,差异具有统计学意义(P0.05)。肿胀疗效:治疗组有效率为68%,对照组有效率为59%,两组比较,差异具有统计学意义(P0.05)。结论:伤科黄药治疗早期胫腓骨骨折疗效显著,可缓解患者的疼痛及肿胀程度。     

黄原酸酯棉在富集微量元素上的应用

研究用黄原酸酯棉吸附富集某些微量元素的可能性，黄原酸酯棉的保存方法、酸度、平衡时间、痕量元素浓度对黄原酸酯棉吸附能力的影响。用本文拟定的方法测定全矿石中的微量银，纯氯化钠试剂中铁、镁、铜等。     

Xanthate‐Mediated Controlled/Living Free‐Radical Polymerization under 60Co γ‐Ray Irradiation: Structure Effect of O‐Group

Summary: The free‐radical polymerizations of vinyl monomers have been studied under ⁶⁰Co γ‐ray irradiation in the presence of S‐benzyl O‐ethyl dithiocarbonate (X1), S‐benzyl O‐phenyl dithiocarbonate (X2), S‐benzyl O‐2‐naphthyl dithiocarbonate (X3), S‐benzyl O‐(4‐methoxyphenyl) dithiocarbonate (X4), and methyl 4‐{[(benzylthio)carbonothioyl]oxy}benzoate (X5), respectively. The results indicate that the polymerizations of methyl acrylate (MA) reveal good living characteristics in the presence of X2, X3, X4, and X5 with O‐aryl groups, which play an important role in polymerization behavior; large aryl groups lead to slow polymerization. In contrast, the polymerizations with X1 couldn't be controlled and the obtained polymers had a broad‐molecular‐weight distribution or were even cross‐linked. In addition, it was observed that the polymerization of styrene with X2 was a controlled process though it was very slow, and the uncontrolled polymerization of methyl methacrylate (MMA) occurred under γ‐ray irradiation. To the best of our knowledge, this is the first report of xanthates being used as control agents in controlled/living free radical polymerization under γ‐ray irradiation.

The structures of the xanthates used here.     

羧甲基降解黄原胶选择性清除血浆LDL/Fib的研究

以黄原胶为原料,进行酸降解,_再以氯乙酸为羧甲基化试剂,在适当的条件下进行羧甲基化反应,获得降解黄原胶羧甲基化衍生物.考察分子质量及酸碱比对产物羧甲基含量的影响,确立较优化的羧甲基化反应条件.并通过红外对结构进行了表征.以降解黄原胶羧甲基化衍生物为净化剂,研究其选择清除血浆中低密度脂蛋白(LDL)及纤维蛋白原(Fib)的性能.结果 表明,在pH=5.20,净化剂浓度为2,500mg/L时,可使血浆总胆固醇(TC)下降40%左右,低密度脂蛋白胆固醇下降45%,纤维蛋白原下降近100%,而总蛋白和高密度脂蛋白(HDL)无明显变化.     

Carbon disulphide absorption during xanthate reagent mixing in a gold mine concentrator

A xanthate reagent mixer at a gold mine concentrator was exposed to carbon disulphide by extensive skin contamination with xanthate powder and solution during the reagent mixing process. Absorption of carbon disulphide was confirmed by the detection of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA). Drager colorimetric tube testing during subsequent mixing recorded a maximum concentration of at least 60 ppm carbon disulphide. An illness consisting of predominantly gastrointestinal symptoms began 20 h after the exposure. Although this may have been due to carbon disulphide toxicity this is by no means certain. The need for engineering controls, impervious protective clothing and full-face respirators with particulate and organic vapour cartridges is discussed. This episode occurred at another mine site, unrelated to Mount Isa Mines Limited.