Synthesis and characterization of biodegradable polyesteramides constructed mainly by alternating diesterdiamide units from N,N′-bis(2-hydroxyethyl)-adipamide and diacids

Two kinds of aliphatic alternating polyesteramide prepolymers were prepared through melt polycondensation from N,N’-bis(2-hydroxyethyl)-adipamide and adipic acid or sebacic acid. Chain extension of them was conducted with 2,2′-(1,4-phenylene)-bis(2-oxazoline) and adipoyl biscaprolactamate as combined chain extenders. The chain extended polyesteramides (ExtPEAs) were characterized by IR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray scattering, tensile test and enzymatic degradation. The results showed that the ExtPEA(4,m)s were mainly constituted with the diester adipamide alternating units. ExtPEA(4,4) and ExtPEA(4,8) had Tm of 83.8℃ and 85.8℃ and initial decomposition temperature above 310.0℃. They crystallized similarly as Nylon-66 did and were flexible thermoplastic materials with tensile strength up to 25.64 MPa and strain at break up to 737%.     

超高分子量聚乙烯烧结制品的链缠结调控及其对性能影响

利用新的单中心Ziegler-Natta(Z-N)催化剂,通过干预分子链的生长与聚集行为,可获得低缠结的超高分子量聚乙烯(UHMWPE)初生树脂.本研究利用这类低缠结UHMWPE,通过设置不同的烧结温度(Ts)来改变熔体缠结状态,并探讨了链缠结程度对烧结制品结构与性能的影响.实验结果表明TS=220℃下,UHMWPE样品发生显著的复缠,造成高缠结度;而Ts=170℃下,初始低缠结状态能够得以充分保留,从而获得了缠结度具有明显差别的不同样品.示差扫描量热法(DSC)测试表明,在Ts=170℃下,低缠结度有利于在随后等温及冷却结晶过程中生成高熔点(最高达141℃)晶体与高的结晶度(最高达65%).力学测试表明低缠结度制品的综合力学性能显著提升,其中屈服强度提高72%,拉伸断裂强度提升139%,弹性模量提升162%以及断裂伸长率提升36%,实现了同时增强增韧.这就提供了一种从调节链缠结温度实现UHMWPE烧结制品高性能化的新思路.     

Diphenyl cyclopropenone-centered polymers for site-specific CO-releasing and chain dissociation

The synthesis and stimuli-responsiveness of a diphenyl cyclopropenone(DPCP)-centered poly(methyl acrylate)(PMA)are presented.DPCP-centered PMA could release carbon monoxide(CO)upon UV light in a switched on-and-off manner.The CO-releasing process can be reported by the variations in photoluminescence spectra.In addition,DPCP moiety covalently embedded in the crosslinked polyurethane could also release CO under UV light.Of special,DPCP-centered PMA in solution was selectively dissociated at the phenol ester bond under the ultrasound,and a force-induced hydrolyzation reaction was revealed by D20 exchanging^1 H NMR spectra.The kinetic study reveals that small quantity of water could enhance the chain scission rate.This work provides a DPCP-centered polymer for sitespecific CO-releasing and chain dissociation.     

Synthesis, Crystal Structure and Electrochemical Properties of One-dimensional Chain Coordination Polymer [Co(Ⅱ)(C6H5CH=CHCOOH)2(4,4''-bipy)(H2O)5]n

A one-dimensional chain coordination polymer [Co(Ⅱ)(C6H5CH=CHCOOH)2(4,4'-bipy)(H2O)5]n has been synthesized with cinnamylic acid, 4,4'-bipy and cobaltous chloride as raw materials. Crystal data for this complex: monoclinic, space group P21/c, a - 1.1481(3), b =1.1230(2), c = 1.1759(3) nm, β = 97.054(4)°, V = 1.5046(6) nm3, Mr= 617.50, Dc = 1.363 g/cm3, Z= 2, μ(MoKα) = 0.627 mm-1, F(000) = 646, S = 1.062, R 0.0443 and wR = 0.1178. The crystal structure shows that two neighboring cobalt(Ⅱ) ions are linked together by one 4,4'-bipy, and the whole complex molecule adopts a one-dimensional chain structure. Each cobalt(Ⅱ) ion is coordinated with two nitrogen atoms from two 4,4'-bipy molecules and four oxygen atoms from four water molecules, giving a distorted octahedral coordination geometry. The electrochemical properties were analyzed by combining with the crystal structure.     

Synthesis and Characterization of Biodegradable Alternating Polyesteramides from Mixed Diamidediols and Sebacic Acid

A series of polyesteramide prepolymers[PrePEA（0/4,8）s] having mixed alternating bisesterdiamide units was synthesized via melt polycondensation from N,N＇-bis（2-hydroxyethyl）oxamide（0） and N,N＇-bis（2-hydroxyethyl）-adipamide（4） with sebacic acid（8） at different molar ratios.Chain extension of them was conducted with 2,2＇-（1,4-phenylene）-bis（2-oxazoline） and adipoyl biscaprolactamate as combined chain extenders.The chain extended polyesteramides[ExtPEA（0/4,8）s] were characterized by proton nuclear magnetic resonance（1H NMR）,gel permeation chromatography（GPC）,differential scanning calorimetry（DSC）,thermogravimetry analysis（TGA）,wide angle X-ray scattering,tensile test and enzymatic degradation.The results show that ExtPEA（0/4,8）s were crystalline polyesteramides.They had Tm up to 136.5 ℃ and initial decomposition temperature above 297.5 ℃.They crystallized in similar crystallites into Nylon-66 and degraded under the catalysis of protease or lipase.They are thermoplastic materials with tensile strength up to 21.5 MPa and elongation at break above 64.0％.     

链状Salen型高分子席夫碱金属配合物的合成及表征

以对苯二甲酰氯为交联剂,利用界面聚合法合成了链状Salen型高分子席夫碱金属配合物PLSBM(M:CoⅡ,MnⅡ,ZnⅡ,CuⅡ),通过元素分析、红外光谱(FT-IR)、扫描电镜(SEM)、电感耦合等离子原子发射光谱(ICP-AES)和X射线光电子能谱(XPS)对结构进行了表征,发现PLSBM呈不规则的链状结构,配位金属离子与配体形成了稳定的配合物后金属离子的结合能增加了0.5～2.1eV。     

不同分子量软链段的聚己内酯型聚氨酯扩链反应动力学研究

合成了一系列不同分子量的聚己内酯,进而制备异氰酸根封端的聚己内酯预聚体,用傅里叶变换红外光谱研究了不同分子量的聚己内酯预聚体与二元醇的扩链反应.扩链反应动力学研究结果表明:聚己内酯预聚体与二元醇的扩链反应均为二级反应;随着软链段反应物料分子量的增加,反应速率常数显著降低,但当分子量超过某一范围后,其对反应速率的影响逐渐减小,趋于不变.对于不同硬链段反应物料含量的扩链反应体系,硬链段反应物料含量越高,软链段反应物料分子量对反应速率的影响越明显,而且,当软链段反应物料分子量超过某一范围后,不同体系的反应速率常数间的差值趋于不变.Arrhenius方程中的指前因子(B)随软链段反应物料分子量的变化关系与速率常数对分子量的依赖关系相同;从反应速率常数对温度的依赖关系可见:表观活化能的直线斜率基本相同,扩链反应的活化能主要与官能团的反应活性相关.     

以双硫酯为链转移剂的活性自由基聚合

合成并研究了两种双硫酯链转移剂的纯化方法 ,进行了多种单体以双硫酯为链转移剂的活性自由基聚合及嵌段共聚 .发现以PhC(S)SC(CH3) 2 Ph为链转移剂的效果比PhC(S)SCH(CH3)Ph好 ,聚合产物的多分散性系数较小 .引发剂与链转移剂的摩尔数比为 1∶3 5～ 1∶4 2时 ,得到多分散性系数小 ,实测分子量与理论分子量相近的聚合产物 .聚合物的分子量随时间和转化率的增加而增加 ,加入第二单体形成嵌段共聚物 ,具有活性聚合特征 .聚甲基丙烯酸酯大分子引发剂引发丙烯酸酯单体聚合时 ,聚合速度最快 .     

菌类多糖链构象及其表征方法研究进展 （专题报道）

 概述了菌类多糖在溶液中链构象及其表征方法的研究进展.主要报道从各种真菌（香菇、茯苓、灵芝、木耳、黄单胞菌、裂褶菌等）中提取的多糖在溶液中的分子量、分子形态和尺寸,即链构象.同时介绍多糖链构象对生物活性的影响,并且指出多糖刚性链带电基团及适量分子量有利于促进它与免疫细胞上受体结合,从而抑制肿瘤细胞增殖.由此表明,多糖链构象的研究对弄清其生物功能和推动生命科学发展十分重要.多糖在溶液中主要以无规线团、双螺旋、三螺旋、蠕虫状、棒状链以及聚集体构象存在,它取决于单糖组成、糖苷键、支链结构以及分子内和分子间作用力.测定链构象的方法主要包括光散射、黏度、显微技术（透射电镜,扫描电镜以及原子力显微镜）、微量热法和小角X-射线散射等.此外,介绍了多糖溶液理论以及计算链构象参数的表达式.