聚乙二醇改性聚乳酸的合成与性能表征

以外消旋乳酸(D,L-LA)和不同数均分子量(Mn)的聚乙二醇(PEG)为原料,通过熔融缩聚法,合成了系列聚乳酸聚乙二醇(PLEG)。最佳工艺条件为:以(Sn(Oct)2)为催化剂,m(Sn(Oct)2)为0.8%,n(PEG)∶n(D,L-LA)=1∶600,聚合温度170℃,压力0.096 MPa条件下,反应8h。用特性粘度测试、FT-IR、XRD、接触角等对其进行表征,实验结果表明系列PLEG中PLEG-800接触角为63°,表明其亲水性能最好;PEG-800和乳酸共聚合成的PLEG的粘均分子量最大,可达48997,与PDLLA相比,结晶度有较大提高,亲水性得到改善。     

可交联亲水性聚硅氧烷的合成与表征

以丙烯酸聚乙二醇酯、甲基丙烯酸缩水甘油酯和含氢硅油为原料在甲苯溶剂中进行硅氢加成反应,红外光谱和核磁共振谱对产物分析表明,合成了一种新型的、可交联的、亲水性有机硅材料.探讨了反应时间、反应温度、反应物的摩尔比对含氢硅油活性氢转化率的影响规律.实验表明,当催化剂用量为反应物质量分数的0.004%时,含氢硅油活性氢(PHMS)、丙烯酸聚乙二醇酯(PEGA)和甲基丙烯酸缩水甘油酯(GMA)的摩尔比为1:1.125:0.1,在85℃下反应8h,含氢硅油活性氢的转化率达到82%.     

低温常压下高分子量左旋聚乳酸的微波合成及表征

以辛酸亚锡为催化剂低温常压下引发左旋丙交酯(LLA)开环聚合,快速高效地合成了性能良好的高分子量左旋聚乳酸(PLLA).通过正交实验研究了催化剂用量、反应温度和时间对产物分子量的影响,在催化剂用量0.21%(质量分数),反应温度100℃,反应时间60min时得到产物粘均分子量高达16.21×104.通过红外光谱(FTIR)、核磁共振氢谱(1H-NMR)对产物的结构进行分析,结果证明利用微波能有效地合成左旋聚乳酸,通过差式扫描量热(DSC)、X衍射(XRD)、旋光度和力学性能对左旋聚乳酸膜的性能进行表征,结果显示产物纯净,其结晶度为85.6%,光学纯度为98%,有良好的力学性能.     

高分子量聚L-乳酸的合成和表征

采用丙交酯开环聚合合成聚L-乳酸(PLLA),研究了引发剂用量、聚合时间对聚L-乳酸分子量的影响.采用FTIR、DSC、TG分析方法对聚乳酸的结构和热性能加以表征.研究结果表明通过对聚合时间以及引发剂用量的控制,合成出高分子量聚L-乳酸.FTIR分析结果证实了聚L-乳酸的结构,DSC分析表明合成出的聚L-乳酸玻璃化转变温度为62℃,结晶度达到42.3%;TG分析表明聚L-乳酸热分解温度为299℃.     

Polymeric nanomedicines based on poly(lactide) and poly(lactide-co-glycolide)

Small molecule chemotherapeutics often have undesired physiochemical and pharmacological properties, such as low solubility, severe side effect and narrow therapeutic index. To address these challenges, polymeric nanomedicine drug delivery technology has been routinely employed, in particular with the use of biodegradable and biocompatible polyesters, such as poly(lactide) (PLA) and poly(lactide-co-glycolide) (PLGA). Here we review the development and use of PLA and PLGA for the delivery of chemotherapeutic agents in the forms of polymer–drug conjugates and nanoconjugates.     

Preparation and characterization of high molecular weight low bandgap polymers based on poly(2,7-carbazole)s for organic solar cells

We report the PCDTBT {Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]}, an alternating copolymer of 2,7-carbazole and dithienyl-2,1,3-benzothiazole, has high molecular weight and narrow molecular weight distribution. Our PCDTBT can be successfully prepared as good yield by using tetrakis(triphenylphosphine)palladium [Pd(PPh3)4] catalyst instead of Pd2dba3/P(o-Tol)3 catalyst. From the UV/Vis absorption spectroscopy, we can observe that absorption bands of PCDTBT are bathochromically shifted by increasing the molecular weight, that is to say, our high molecular weight PCDTBT can absorb much longer wavelength light compare to low molecular weight PCDTBT. The best performance can be obtained from device based on the mixture of PCDTBT (polymer-30) and PC70BM {[6,6]-phenyl C71-butyric acid methyl ester} (1:4) as an active layer, which shows 4.50% of PCE with 10.1 mA/cm2 of short-circuit current density (J(SC)), 0.85 V of open-circuit voltage (V(OC)), and 52.3% of fill factor which is very similar with Leclerc's published result.     

Freeze-drying of low molecular weight poly(L-lactic acid) nanoparticles: effect of cryo- and lyoprotectants

The chemical and physical stability of polymeric nanoparticles is poor in aqueous suspensions, and the drying of these particles is often problematic. In the present study, the stability of freeze-dried low molecular weight poly(L-lactic acid) (PLA) nanoparticles was enhanced by adding glucose and/or lactose to the formulation as cryo- and lyoprotectants, respectively. Also the effect of an extra stabilizer, Tween 80, was studied. The best freeze-dried PLA nanoparticle formulations were achieved, when glucose and lactose were added in combination so that the amount of lactose was double the amount of glucose. With this combination the redispersion of high-quality nanoparticles (homogenous particle dispersion with original size and without aggregates) was achieved. The addition of Tween 80 further improved the quality of freeze-dried PLA nanoparticles by facilitating the redispersion of the lyophilized cake into optimal nanoparticles.     

Synthesis and characterization of multiwalled carbon nanotube reinforced ultra high molecular weight polyethylene composite by electrostatic spraying technique

In the present work, multiwalled carbon nanotube (MWNT) reinforced UHMWPE composite films were prepared by electrostatic spraying followed by consolidation. X-ray diffraction and differential scanning calorimetry studies showed a decrease in the crystallinity of UHMWPE due to the nature of the fabrication process as well as addition of MWNT. Tensile test showed an 82% increase in the Young’s modulus, decrease in stress to failure from 14.3 to 12.4 MPa and strain to failure from 3.9% to 1.4% due to 5% addition of MWNT. Raman spectra showed the presence of compressive stresses in the nanotubes. Fracture surface showed presence of pullout like phenomena in the MWNT reinforced film.     

含亚苯基甲基苯基硅树脂的合成及表征

以甲基、苯基氯硅烷和1,4-二(羟基二甲基硅基)苯为原料,采用水解-缩聚法合成了主链含亚苯基的甲基苯基有机硅树脂,并对其结构和性能进行了研究。红外光谱(FT-IR)和核磁共振(29Si NMR)分析表明,亚苯基被成功引入到硅树脂主链中。差式量热扫描(DSC)分析表明硅树脂为均聚物。热失重(TG)结果表明,在N2氛中,硅树脂在450℃失重约1%,优于普通甲基苯基硅树脂。硅树脂的清漆涂层在300℃下使用时,附着力、抗冲击、柔韧性能仍保持良好。电化学阻抗分析(EIS)结果表明,硅树脂的清漆涂层常温固化后、经300℃的高温烘烤后都具有优良的耐腐蚀性能。     

二联噻吩和联苯胺类交替共聚物的合成及表征

以联苯二胺及二甲基联苯二胺为原料,合成了相应的N,N′-二氯联苯醌胺单体,并以二价镍配合物为催化剂与二连噻吩共聚得到了相应的交替共聚物。所得聚合物通过FT-IR,1H-NMR进行了表征。所得聚合物紫外-可见光谱分别在330、437、327、410nm处最大吸收峰出现。所得聚合物在-0.1～0.8V之间进行循环伏安分析,每一个聚合物都观察到两对氧化峰和还原峰分别在(Epa=0.40V/Epc=0.31V和Epa=0.70V/Epc=0.56V)和(Epa=0.33V/Epc=0.28V和Epa=0.63V/Epc=0.50V)。     

聚(2,5-二丁氧基)对苯乙炔的合成及性能研究

利用强碱去氯综合法,超声合成了光电聚合物-聚(2,5-二丁氧基)对苯乙炔(PDBOPV),并探索了温度、超声反应时间以及强碱用量对产率的影响,用红外光谱进行了结构表征,并研究了溶解性、光吸收特性、热稳定性等性能.     

片状纳米聚对苯二胺的制备与表征

以盐酸为掺杂剂,过硫酸铵为氧化剂,采用溶液聚合,合成了片状结构的聚对苯二胺.通过红外光谱(FT-IR)、X射线衍射(XRD)、热分析(TGA/DSC)和扫描电子显微镜(SEM)分别对产物的结构、结晶性、热稳定性和微观形貌进行了表征.结果表明,所得的聚对苯二胺纳米片具有一定的结晶性和良好的热稳定性,聚对苯二胺的形貌与n(HCl)∶n(p-PDA)的比例有关,当n(HCl)∶n(p-PDA)=0.8时最易形成片状纳米聚对苯二胺.讨论了聚对苯二胺纳米片可能的形成机理.     

聚3-烷基噻吩系列物的合成与表征

采用Fe(III)催化剂合成法合成聚3-丁基噻吩(P3BT)、聚3-己基噻吩(P3HT)和聚3-十二烷基噻吩(P3DDT)。用GPC和1 H-NMR对所合成的聚合物的相对分子质量和结构进行表征,用SEM对所合成的聚合物的表面形貌进行观察,并用紫外-可见吸收光谱和荧光光谱研究3种聚合物氯仿溶液的光学性能。结果表明,用该方法合成的聚合物以非晶态形式存在;具有较高的相对分子质量;在氯仿溶液中,P3BT、P3HT、P3DDT的最大吸收峰分别为:436nm、437nm和430nm,最大发射峰分别为570.0nm、581.2nm和573.8nm。综合分析发现P3HT更适于用做聚合物太阳能电池材料。     

易溶性聚(N-乙基苯胺)的合成及表征

采用乳液聚合法合成了具有较好溶解性能的聚(N-乙基苯胺),并用红外光谱和紫外光谱对聚合产物进行了表征.研究表明,乳化剂的用量对产物的分子量和产率有较大的影响,当乳化剂/单体摩尔比为1:2时,聚(N-乙基苯胺)具有最大的分子量和产率.盐酸掺杂态聚(N-乙基苯胺)的电导率为1.03×10-5S cm-1.此外,聚(N-乙基苯胺)具有明显的溶致变色性能.     

Layer-by-Layer crystallization of enantiomeric poly(lactide)s

Poly(lactide)s stereocomplex ultrathin film with controlled structure at a molecular level was able to be prepared by stepwise assembly using the stereocomplex interaction. Pure stereocomplex crystal can be easily obtained by using this technique. When the substrates pre-coated with the stereocomplex assembly were immersed into solution of poly(L-lactide) or poly(D-lactide) for a long time, each polymer was homogeneously deposited on the substrates. The enantiomer was epitaxially crystallized on the stereocomplex film. The XRD pattern of the films showed similar characteristic peaks of the stereocomplex, indicating that the crystallization was influenced by conformation of polymer at the substrate. This is the first case of the epitaxially growth of polymers on the structurally regulated surface. These films had high degree of crystallinity although the assemblies did not undergo a crystallization process. This method was considered to be a general method that can be applied to other polymers, which able to form stereocomplex.     

高分子量聚丁二酸丁二醇酯的制备及性能研究

以1,4-丁二醇和丁二酸为原料,通过加入少量的扩链剂,利用直接缩聚法在短时间内合成了高分子量的聚丁二酸丁二醇酯(PBS).采用GPC、DSC以及TGA等方法对产物进行了表征,同时研究了扩链剂的加入对聚合物性能的影响.结果表明,当扩链剂加入量为PBS预聚物的2.5％时,扩链产物的性能最佳,重均分子量由3万上升到17万,拉...     

聚1-萘胺纳米颗粒的合成及表征

采用界面聚合法合成了聚(1-萘胺)纳米颗粒.利用红外光谱(FT-IR),紫外可见吸收光谱(UV-vis),电子扫描显微镜(SEM),投射电镜(TEM),X射线衍射(XRD),循环伏安(cyclic voltammogram)等测试方法,对聚合物进行了表征并对聚合物形貌、结构及性能进行了初步探讨.结果表明,界面聚合法合成的聚(1-萘胺)呈现直径在100nm内的颗粒状分布;XRD结果显示,聚(1-萘胺)为半结晶态聚合物;界面聚合法合成的聚(1-萘胺)具有一定的电化学活性.     

含苯并硒二唑组分的聚对苯撑乙炔类共轭聚合物的合成及性能研究

通过钯催化的Sonagashira偶合反应合成出了3种带有不同链长烷氧基侧链,主链中含有2,1,3-苯并硒二唑纽分的聚苯乙炔类共轭聚合物并对其化学结构进行了表征确认.此类聚合物在常用的有机溶剂中具有较好的溶解性和成膜性.通过紫外可见光谱、荧光光谱、循环伏安等对所得聚合物的基本性能进行了探讨.聚合物P7、P9和P12在溶液状态下的紫外吸收分别为421、450和450nm,相对应最大发射分别位于475、482和481nm;固态下聚合物的吸收分别为433、486和486nm,相对应最大发射为575、583和590nm.聚合物的循环伏安测试表明聚合物P7、P9、P12的起始电位为1.19、1.19、1.18V.聚合物非线性光学性能研究表明取代基为十二碳烷氧基的聚合物显示出了良好的三阶非线性光学性能,其三阶非线性光学系数为3.54×10-12esu.