焦磷酸络锰三价离子引发淀粉-丙烯酰胺的接枝共聚合

将带有极性基团的乙烯类单体通过化学接枝到淀粉或纤维素之类的天然多糖上,可作为絮凝剂、脱除剂和粘接剂^[1～3],近来已发展为高吸水性材料和石油分离剂^[4]。用Ce⁴⁺引发乙烯类单体接枝到淀粉和纤维素类已有报道^[5]。Rayonier用Mn³⁺的焦磷酸盐络合物引发接枝乙烯类单体至纤维素及其衍生物上^[6];Cenita等用Mn³⁺引发MMA、AN接枝淀粉^[7]。本文以焦磷酸络锰离子(Mn³⁺)作引发剂、丙烯酰胺(AM)为单体、淀粉为接枝基体进行接枝共聚,这一工作目前在国内外尚未见报道。     

PEEK-PEDEK嵌段共聚物非等温结晶动力学研究

PEEK以其优异的热稳定性和耐溶剂性被广泛应用在航空航天和电子电气等领域^[1].经过增强后的PEEK长期使用温度(UL温度指数)可达523 K.但在温度高于523 K的情况下,模量下降较快,这在一定程度上限制了其应用.在PEEK的分子链上引入刚性较强地联苯基团,可以有效的提高分子链的刚性,使聚合物的玻璃化转变温度得以提高^[2,3].我们曾合成了一系列含有刚性单体联苯二酚的嵌段共聚物,并对其热性能进行了研究^[4],本文着重对这一系列共聚物的非等温结晶动力学进行研究.     

自旋标记荧光探针表征生物活性分子的自由基损伤

生命过程中产生的经基自由基(^˙OH)已引起广泛关注.目前,对于^˙OH的研究主要集中在直接对^˙OH进行定量表征^[1~3]和问接检测^˙OH诱导损伤生物大分了的损伤产物.^˙OH诱导损伤生物大分了,能够产生大量的碳中心自由基^[4,5].     

小分子玉米肽Leu-Asp-Tyr-Glu保护线粒体抗氧化损伤的研究

线粒体是细胞内氧代谢的主要场所,其膜上富含不饱和脂肪酸,使得线粒体成为自由基进攻的主要靶部位^[1].自由基作用于线粒体膜发生脂质过氧化损伤反应,引起膜的结构与功能改变,使得膜上一系列重要的酶空间排列紊乱,活性降低,膜的通透性改变,诱发多种疾病^[2].目前,抗氧化肽类作为一种非酶类自由基清除剂的研究正在兴起^[3].来源于玉米醇溶蛋白酶降解物中的低分子量肽具有许多重要的生理功能,如促进乙醇代谢、抗疲劳作用以及降血脂等功效^[4].而这些功能的实现主要依赖于其抗氧化活性^[5].最近,我们从玉米蛋白酶解物中获得了一种新的小分子抗氧化肽Leu-Asp-Tyr-Glu(LD YE,LD YE经文献检索为一种新的寡肽)^[6].     

十二烷基磺酸钠对丙烯酰胺－烯丙基磺酸钠共聚物溶液粘度的影响

丙烯酞胺-烯丙基磺酸钠共聚物(PASA)优良的絮凝性能已在前文^[1]中报道.本文主要考察阴离子表面活性剂R₁₂SO₃Na对其溶液粘度的影响,并与PAM做了对照.     

掺杂态聚苯胺蜂窝状有序多孔薄膜的制备及形成机制的探讨

近年来,由于微米、亚微米及纳米级有序多孔结构薄膜可以用于催化、生物培养基材、分离或吸附介质、光子晶体等诸多方面从而引起了科学家们极大的研究兴趣^[1～6].微制作是使材料表面具有新性能的重要手段,激光刻蚀及其相关技术已经被应用于不同表面的微图案化和微器件的制作^[7],另外,还可通过自组装技术进行多孔薄膜的制备^[8,9].Francois等^[10]于1994年首次提出了水辅助方法(Water-A ssisted Fab-rication),即在高湿度的环境下,以冷凝水滴为模板,在固体基片上制备了孔径分布均一,排列紧密的蜂窝状有序多孔薄膜.继而人们对此方法做了进一步的研究,不仅突破了最初的聚苯乙烯及其共聚物体系^[10～13],而且使用双亲共聚物^[14]、聚离子复合物^[15]和TiO₂前驱体的混合物^[16]等成功地获得了蜂窝状有序多孔薄膜,同时系统地研究了成膜体系及成膜条件对形成蜂窝状有序多孔薄膜的影响,并对形成机制进行了探讨.聚苯胺是典型的导电高分子,有关聚苯胺有序多孔结构薄膜的研究已有报道^[17～19].本文采用水辅助方法,在高湿度环境下,使用4-十二烷基苯磺酸掺杂的聚苯胺(PANI-DBSA)为成膜材料,制备了双层蜂窝状有序多孔薄膜,并通过原子力显微镜(A FM)对薄膜的形貌和电学性质进行了表征.同时在已有成膜机制的基础上,提出了该双层蜂窝状有序多孔薄膜的形成机制.     

活性聚甲基丙烯酸甲酯和溴甲基化聚苯乙烯偶合反应制备接枝共聚物

采用基团转移聚合、阴离子聚合以及高分子偶合反应的方法,合成了一种结构明确、链长均匀和分子量可控的聚苯乙烯接枝聚甲基丙烯酸甲酯。主链聚苯乙烯由阴离子聚合得到,并进行溴甲基化。支链活性聚甲基丙烯酸甲酯由基团转移聚合制备。经偶合反应后得到分子量为3×10⁴～7×10⁴、多分散性指数D为1.2～1.4的接枝共聚物。溴甲基化聚苯乙烯和活性聚甲基丙烯酸甲酯的偶合反应活性随分子量的增大而降低,理想的反应温度为-20℃。用¹HNMR、GPC和DSC表征接枝产物。和均聚物相比,共聚物的玻璃化温度较低。     

淀粉-磺甲基化聚丙烯酰胺接枝共聚物的合成及性能

用淀粉-聚丙烯酰胺接枝共聚物(S-g-PAM)同多聚甲醛及亚硫酸钠反应,合成了淀粉-磺甲基化聚丙烯酰胺接枝共聚物(S-g-SPAM)。该磺化物的水溶液在试验浓度范围内(0.1～1.0％),为假塑性流体,对高岭土悬浮液的絮凝,由沉降速度,上层清液相对吸光度可知,S-g-SPAM(接枝链分子量为1.03×10⁵,磺甲基化度30％)的絮凝能力优于相应的未磺化的S-g-PAM,也比聚丙烯酰胺(分子量2.5×10⁶)强。     

含铕荧光两亲接枝共聚物的制备及胶束化行为

以丙烯酸(AA)、 苯甲酸(BA)和邻菲啰啉(Phen)为配体, Eu³⁺为中心离子, 制备了可聚合荧光配合物单体, 并以此单体为功能单体, 聚乙二醇单甲醚甲基丙烯酸酯(MPEGMA)和甲基丙烯酸六氟丁酯(HFMA)为共聚单体, 通过溶液聚合制备出含铕两亲荧光接枝共聚物P-[HFMA-co-Eu(AA)(BA)₂Phen]g-PEG. 利用红外光谱(FTIR)和核磁共振波谱(¹H NMR和¹⁹F NMR)对共聚物的结构进行表征; 采用表面张力法测定共聚物的临界胶束浓度(cmc)为0.20 g/L; 通过透射电子显微镜(TEM)和动态光散射仪(DLS)观察胶束的形貌及其胶束化行为, 发现该共聚物可以形成大小均一的球形胶束, 且随着共聚物浓度的提高, 胶束粒径相应增大; 在溶液浓度达到临界胶束浓度时, 溶液荧光出现强度突变.     

基团转移聚合法合成A-B型嵌段共聚物

用基团转移聚合法(GTP)合成嵌段共聚物是近年来国际上高分子研究的热门之一.在室温下制备嵌段共聚物是GTP的一大特点.本文利用三类不同GTP单体的活性差别^[1,2],控制适当的加料顺序及聚合条件,首次用GTP法合成含丙烯腈嵌段的A-B型共聚物并进行表征.     

β-蒎烯嵌段、接枝共聚物的合成

分别使用苯乙烯 HCl加成物 (a)和 2 氯乙基乙烯基醚 HCl加成物 (b)作为引发剂 ,TiCl4 Ti(OiPr) 4(3∶1mol mol)为活化剂 ,在nBu4NCl存在下 ,- 40℃、CH2 Cl2 中 ,通过顺序活性阳离子聚合 ,合成了 β 蒎烯与苯乙烯、对甲基苯乙烯的嵌段共聚物 .又用带丙烯酰氧功能基的引发剂c [CH3CH (OCH2 CH2 X )Cl,X =OCOC(CH3)CH2 ]引发 β 蒎烯活性阳离子聚合 ,合成了 β 蒎烯大分子单体 .该大分子单体在AIBN引发下与甲基丙烯酸甲酯进行自由基共聚 ,获得主链为聚甲基丙烯酸甲酯、侧链为聚 β 蒎烯的接枝共聚物     

Synthesis and characterization of anionic graft copolymers containing poly(ethylene oxide) grafts

Anionic graft copolymers were synthesized through grafting of poly(ethylene glycol) monomethyl ether (MPEG) onto terpolymers containing succicinic anhydride groups. The backbone polymers were prepared through radical terpolymerization of maleic anhydride, styrene, and one of the following monomers: methyl methacrylate, ethylhexyl methacrylate, and diethyl fumarate. MPEG of different molecular weights were grafted onto the backbone through reactions with the cyclic anhydride groups. In this reaction one carboxylic acid group is formed together with each ester bond. The molecular weights of MPEG were found to influence the rate of the grafting reaction and the final degree of conversion. The graft copolymers were characterized by IR, GPC, and ¹H-NMR. Thermal properties were examined by DSC. Graft copolymers containing 50% w/w of MPEG 2000 grafts were found to be almost completely amorphous, presumably because of crosslinking, and hydrogen bonding between carboxylic acid groups in the backbone and the ether oxygens in MPEG grafts. © 1995 John Wiley & Sons, Inc.     

Modification of Maleic Anhydride Copolymers with Aliphatic Alkylamines and Sulfanilamide

Russian Journal of Applied Chemistry - Macromolecular amides were synthesized from copolymers of maleic anhydride with styrene or vinyl acetate and amines: ethylamine, propylamine, and...     

Blends of styrene/maleic anhydride copolymers with polymethacrylates

The phase behavior of a series of styrene/maleic anhydride (SMA) copolymers with various polyacrylate and polymethacrylate homopolymers has been investigated using various techniques. None of the polyacrylates are miscible with SMA copolymers. Poly (methyl methacrylate) (PMMA) poly(ethyl methacrylate) (PEMA) and poly(n-propyl methacrylate) (PnPMA), are miscible with these copolymers over a certain range of maleic anhydride contents; whereas, the higher methacrylates apparently have no region of miscibility. For PEMA and PnPMA, the miscibility windows extend through 0% MA; hence, polystyrene is miscible with these polymethacrylates although the lower critical solution temperature is quite low. The exothermic heat of mixing styrene and ester analogs found here supports the observed miscibility of polystyrene with ethyl, n-propyl, and cyclohexyl (reported elsewhere) methacrylates. Lattice fluid interaction parameters for styrene-methacrylate obtained from the cloud points of these blends agree quite well with the Flory—Huggins parameters obtained from copolymer miscibility windows.     

Reactive polymers on the basis of functional peroxides

The copolymerization constants of new monomer containing ditertiary peroxide groups with styrene have been determined. The peroxide monomers were prepared by the acylation of 3-(tert-butylperoxy)-3-methyl-1-butanol with methacryloyl chloride or maleic anhydride in the presence of tertiary amines. Peroxide containing copolymers were obtained by copolymerization of peroxyalkyl methacrylate and peroxyalkyl maleate with styrene.     

Hyperbranched polymers with maleic functional groups as radical crosslinkers

The crosslinking performance of the unsaturated hyperbranched polyester poly(allyloxy maleic acid‐co‐maleic anhydride) (MAHP) was investigated with copolymerizations of three different monomers: styrene, vinyl acetate, and methyl methacrylate. Both styrene and vinyl acetate afforded interpenetrating‐polymer‐network copolymer gels. The gels exhibited crosslink density gradients through the polymer matrices on a macroscopic level, and density maximums were concentrated around the MAHP moieties. The heterogeneity of the gels is briefly discussed in terms of a modified two‐phase model, where one phase consists of an elastic part of low crosslinking density and the other phase consists of an inelastic dendritic part with a highly condensed bond density. Unlike the two‐phase model developed by Choquet and Rietsch, the modified two‐phase model takes into account that both phases swell in good solvents. Unlike copolymerizations employing styrene or vinyl acetate, the copolymerization of MAHP with methyl methacrylate afforded noncrosslinked starbranched copolymers that consisted of a MAHP core from which long poly(methyl methacrylate) branches were protruding. The different behaviors of the copolymerizations of the three monomers used in this study can rationally be explained by their different reactivity ratios with maleic end groups of MAHP. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 964–972, 2001     

Polymers from renewable resources. II. A study in the radio chemical grafting of poly(styrene‐alt‐maleic anhydride) onto cellulose extracted from pine needles

A binary mixture of styrene and maleic anhydride has been graft copolymerized onto cellulose extracted from Pinus roxburghii needles. The reaction was initiated with gamma rays in air by the simultaneous irradiation method. Graft copolymerization was studied under optimum conditions of total dose of radiation, amount of water, and molar concentration previously worked out for grafting styrene onto cellulose. Percentage of total conversion (Pg), grafting efficiency (%), percentage of grafting (Pg), and rates of polymerization (R_p), grafting (R_g), and homopolymerization (R_h) have been determined as a function of maleic anhydride concentration. The high degree of kinetic regularity and the linear dependence of the rate of polymerization on maleic anhydride concentration, along with the low and nearly constant rate of homopolymerization suggest that the monomers first form a complexomer which then polymerizes to form grafted chains with an alternating sequence. Grafting parameters and reaction rates achieve maximum values when the molar ratio of styrene to maleic anhydride is 1 : 1. Further evidence for the alternating monomer sequence is obtained from quantitatively evaluating the composition of the grafted chains from the FT‐IR spectra, in which the ratio of anhydride absorbance to aromatic (CC) absorbance for the stretching bands assigned to the grafted monomers remained constant and independent of the feed ratio of maleic anhydride to styrene. Thermal behaviour of the graft copolymers revealed that all graft copolymers exhibit single stage decomposition with characteristic transitions at 161–165°C and 290–300°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1763–1769, 1999     

N-取代马来酰亚胺和苯乙烯的原子转移自由基共聚合

近来,以卤代烷、铜（Ⅰ）卤素盐和２,２ 联吡啶体系引发苯乙烯可进行活性聚合,即原子转移自由基聚合（ＡＴＲＰ）,得到指定分子量和窄分子量分布的聚合物［１］,开辟了活性聚合的一个新领域,引起了广泛的关注．利用ＡＴＲＰ方法,对合成较窄的分子量分布的均聚物...     

在负载H3PO4的固体上3,3,4-三甲基-4-戊烯-2-酮的催化合成

3,3,4-Trimethyl-4-penten-2-one has been synthesized by the acylation of 2,3-dimethyl-2-butene with acetic anhydride in the presence of soild-supported H3PO4.By comparison of the acylation reactions of 2,3-dimethyl-2-butene with acetic anhydride over various soilds-supported H3PO4,it was found that K10 clay,silicagel,HY zeolite and HMordenite were good supports.The results obtined indicate that the soild-supported small amounts of H3PO4 possessed higher catalytic activities,For obatining a higher yield of 3,3,4-trimethyl-4-penten-2-one different supports required different modification methods.     

可聚合的光引发转移终止剂合成接枝共聚物

采用一种可聚合的光引发转移终止剂 ,2 N ,N 二乙基二硫代氨基甲酰氧基乙酸 β 甲基丙烯酰氧基乙酯 (MAEDCA) ,通过两种途径制备了含有聚甲基丙烯酸甲酯 (PMMA)和聚苯乙烯 (PSt)链段的接枝共聚物 .其一是将MAEDCA作为引发剂 ,在紫外光照射下引发MMA聚合 ,得到大分子单体 ,通过大分子单体与St的共聚合得到 .考察了所用大分子单体的分子量和浓度对共聚合的影响 .其二是将MAEDCA作为单体与MMA共聚得到侧链上含有N ,N 二乙基二硫代氨基甲酰氧基 (DC)基团的无规共聚物 ,P(MMA co MAEDCA) .在紫外光照射下 ,P(MMA co MAEDCA)作为大分子引发剂引发St聚合 ,得到P(MMA co MAEDCA) g PSt的共聚物 ,研究了接枝共聚合过程的活性自由基聚合特征