共查询到20条相似文献,搜索用时 250 毫秒
1.
由异山梨醇和苯膦酰二氯经本体聚合法和溶液聚合法得到了不同分子量的新型聚磷酸酯(PPI),采用傅立叶变换红外(FTIR),核磁共振氢谱(~1H-NMR)和凝胶渗透色谱(GPC)对聚酯的组成和分子量进行表征,结果表明产物为聚磷酸酯结构.聚合物在水溶液和酶溶液中的降解和溶胀实验表明,当PPI的分子量(M_w)低于5×10~4时,聚合物具有很好的降解性能和溶胀性能,25天后其降解率达到80%,溶胀率达到150%.当M_w高于5×10~4时,其降解速率和吸水率明显下降,25天后降解率和溶胀率分别仅为25%和40%.研究了PPI的玻璃化转变温度(T_g)和分子量的关系,PPI具有较高的Tg,且随着分子量的增加,聚合物的T_g显著增加.当PPI的分子量为6×10~4时,其玻璃化转变温度达到176℃.同时研究了聚合物分子量对其热稳定性的影响,当重均分子量由2×10~4增加到6×10~4时,PPI的起始分解温度从260℃提高到315℃.结果表明提高分子量有助于提高PPI的热分解温度. 相似文献
2.
可注射性骨组织工程支架材料不饱和聚磷酸酯的合成 总被引:6,自引:0,他引:6
以富马酸、1,2-丙二醇和三氯氧磷为起始原料,合成了主链重复结构单元中含不饱和双键的聚磷酸酯.FTIR及NMR研究表明.不饱和聚磷酸酯(UPPE)主链结构中含有富马酸二(1,2-丙二醇)酯(BPGF)的三种异构体.利用GPC研究了反应时间对聚合反应的影响,结果表明,延长反应时间有利于提高分子量,聚合物趋向于单分散性.反应18 h后,聚合物重均分子量达到5 956 g/mol,分散度为1.12.通过测定UPPE与N-乙烯基吡咯烷酮(NVP)的交联温度曲线,确定交联反应最高温度为41.14-82.30℃,固化时间在1.95-10.28 m in之间. 相似文献
3.
Fe-Zn双金属氰化物催化环氧丙烷开环聚合的研究 总被引:5,自引:0,他引:5
用Fe Zn双金属氰化物 (DMC)催化剂合成了数均分子量 30 0 0~ 12 0 0 0的聚氧化丙烯二元醇 .着重考察了聚合反应的温度、加料方式等对聚合物分子量及分布的影响 ,并初步探讨了Fe Zn双金属氰化物催化环氧丙烷开环聚合的反应特征 .实验发现 ,采用Fe ZnDMC催化剂 ,聚合物分子量可控 ;在较高温度下聚合所得的聚合物分子量分布呈双峰形 ,显示反应体系中至少存在两类活性中心 ,这可能与催化剂中存在两种价态的络合物有关 ,当降低聚合温度时 ,聚合物分子量分布呈单峰形 ,可能是一类活性中心没有引发 ;实验中还发现单体分批加料时聚合物分子量分布较窄 ,而一步加料法所得聚合物分子量分布则很宽 相似文献
4.
5.
6.
《化学进展》2017,(Z2)
极性单体是指带有极性基团的烯烃类单体,主要包括含卤素类极性单体、含氧类极性单体、含氮类极性单体和含磷类极性单体。其中带有乙烯基且与所带极性基团相共轭的极性单体称为极性乙烯基单体,如甲基丙烯酸甲酯、2-乙烯基吡啶和乙烯基磷酸酯等。这类单体所形成的极性乙烯基聚合物是极性基团作为侧链的烯烃聚合物,该类化合物在黏性、韧性、界面性质(染色性和印刷性)、与溶剂或其他聚合物的相容性方面较传统非极性聚烯烃材料有明显的优势。为了使聚合物具有好的物理性能,获得具有一定规整度的聚合物是近年来研究的热点。聚合物的立体结构对其本身的物理性能有着显著的影响,如熔点、玻璃化转变温度和机械性能等。获取立构规整性聚合物的最有效方式是发展催化聚合反应的立体选择性催化剂。本文综述了近几年极性乙烯基单体立体选择性聚合催化剂的研究进展,这里所涉及的极性乙烯基单体包括:丙烯酸酯类、丙烯酸酰胺、乙烯基磷酸酯、乙烯基吡啶和杂原子取代苯乙烯单体。所涉及的聚合体系是配位聚合、路易斯酸碱对和阴离子聚合体系。 相似文献
7.
氨基酸类聚合物具有良好的生物相容性及可降解性,逐渐成为重要的生物医药材料.通过氨基酸环内酸酐(NCA)开环聚合可以得到聚氨基酸,或者氨基酸与非氨基酸共聚物.该方法具有简便、高效及产率高等优点,且聚合物分子量及分子量分布可控.本文归纳总结了NCA开环聚合的原理,NCA单体和多肽聚合物的合成方法,聚氨基酸在水凝胶、多肽膜、多肽粘结剂、抗菌肽及自组装等领域的应用,利用聚乙二醇、聚酯、硅氧烷和壳聚糖等修饰聚氨基酸的进展,并展望了该领域未来发展方向. 相似文献
8.
9.
报道了一种新的苯氧乙酰基四羰基钴催化剂, 并将其用于催化亚胺与一氧化碳的交替共聚反应. 1H NMR分析结果表明, 该催化剂在1个大气压的CO气氛下以烷基钴和酰基钴平衡的形式存在. 催化反应结果表明, 该催化剂具有良好的催化性能, 可以得到具有较高分子量、 N端为苯氧乙酰基的多肽类聚合物, 且具有较窄的分子量分布. 利用核磁共振、 红外光谱和质谱等对多肽聚合物的结构进行了表征, 结果表明, 聚合物链终止端除了具有慕尼黑酮类结构的端基以外, 还存在酰胺类的端基, 并对后者的生成机制进行了解释. 相似文献
10.
报道了一种新的苯氧乙酰基四羰基钴催化剂,并将其用于催化亚胺与一氧化碳的交替共聚反应. 1H NMR分析结果表明,该催化剂在1个大气压的CO气氛下以烷基钴和酰基钴平衡的形式存在. 催化反应结果表明,该催化剂具有良好的催化性能,可以得到具有较高分子量、N端为苯氧乙酰基的多肽类聚合物,且具有较窄的分子量分布. 利用核磁共振\,红外光谱和质谱等对多肽聚合物的结构进行了表征,结果表明,聚合物链终止端除了具有慕尼黑酮类结构的端基以外,还存在酰胺类的端基,并对后者的生成机制进行了解释. 相似文献
11.
Sarah E. Stidham Benjamin H. Weinberg Mark W. Grinstaff 《Journal of polymer science. Part A, Polymer chemistry》2012,50(24):5185-5190
5‐Norbornene‐2‐ethyl ester (mixture of endo and exo) is polymerized via ring‐opening metathesis polymerization, yielding polymers with molecular weights ranging from 50,000 to 5,000,000 g/mol. The polymers are hydroxylated and saponified without alteration of the molecular weight. The polymers are analyzed by NMR, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Films are cast from the polymers at several molecular weights and their rheological properties are investigated. The results showed greater solid‐like character with increasing molecular weight for all polymers analyzed. Cell viability studies showed that the films possessed minimal cytotoxicity. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
12.
Quaternary ammonium salt polymers, a kind of polyelectrolyte with a quaternary ammonium group, are widely used in traditional and emerging industries due to their good water-solubility, adjustable cationicity and molecular weight, high efficiency and nontoxicity. In this paper, firstly, the properties and several synthesis methods of typical quaternary ammonium salt monomers were introduced. Secondly, the research progress on the synthesis of polymers was summarized from the perspective of obtaining products with high molecular weight, narrow molecular weight distribution and high monomer conversion, and special functional polymers. Thirdly, the relationships between the structures and properties of the polymer were analyzed from the perspectives of molecular weight, charge density, structural stability, and microstructural regulation of the polymer chain unit. Fourthly, typical examples of quaternary ammonium salt polymers in the application fields of water treatment, daily chemicals, petroleum exploitation, papermaking, and textile printing and dyeing were listed. Finally, constructive suggestions were put forward on developing quaternary ammonium salt polymers with high molecular weights, strengthening the research on the relationships between the structures and their properties and pinpointing relevant application fields. 相似文献
13.
Paul M. Hergenrother 《Journal of polymer science. Part A, Polymer chemistry》1974,12(12):2857-2872
A series of new high molecular weight soluble ester phenyl-as-triazine and ester phenyl-quinoxaline polymers were prepared by solution cyclopolycondensation of oxalamidrazone or 3,3′-diaminobenzidine, respectively, with various bis(benzilyl)esters. Ester groups are incorporated within the backbone of the polymer chain and also as pendant groups on the heterocyclic ring. By TGA in air, initial weight losses for the all-aromatic polyester phenyl-as-triazines and polyester phenylquinoxalines began at ca. 350 and 400°C, respectively. Films of ester phenyl-as-triazine and ester phenylquinoxaline polymers exhibited good thermo-oxidative stability after aging in circulating air at 232 and 288°C, respectively. Two phenylquinoxaline model compounds were also prepared. 相似文献
14.
Ultrasonic and dielectric relaxation measurements are reported as a function of frequency and temperature for a series of segmented ester polyurethanes. Glass transitions for the ester block were determined using a combination of differential scanning calorimetry and dilatometry. The activation energy associated with the dipolar relaxation of the ester group was found to be sensitive to changes in the molecular weight and the relative proportions of the ester and isocyanate in the polymers. These data are discussed with reference to the morphological changes which are known to occur in these systems. 相似文献
15.
G. R. Dever F. E. Karasz W. J. MacKnight R. W. Lenz 《Journal of polymer science. Part A, Polymer chemistry》1975,13(9):2151-2179
Polymers of different tacticities, from highly isotactic to highly syndiotactic, were prepared from methyl, ethyl, and isopropyl α-chloroacrylates. These polymers were characterized for tacticity by infrared spectroscopy and 100 and 300 MHz nuclear magnetic resonance (NMR) and for thermal properties by differential scanning calorimetry (DSC). After corrections were made for molecular weight effects, the observed glass temperature-tacticity results were analyzed, and it was determined that the maximum differences in glass temperatures of the purely isotactic compared to the purely syndiotactic polymers should be 92°C for the methyl ester, 86°C for the ethyl ester, and 68°C for the isopropyl ester polymers. The highly isotactic polymers of all three esters were crystalline. Possible polymerization reaction mechanisms are discussed on the basis of the triad and tetrad tacticity values observed and the calculated propagation statistics. 相似文献
16.
Wakichi Fukuda C. S. Marvel 《Journal of polymer science. Part A, Polymer chemistry》1968,6(5):1281-1291
The vinyl ester of dehydrogenated abietic acid has been homopolymerized, copolymerized with vinyl chloride, vinyl acetate, and butadiene and terpolymerized with styrene and acrylonitrile. Both in the homopolymerization and the copolymerization, the vinyl ester of dehydroabietic acid has given lower molecular weight polymers than were obtained with the vinyl ester of tetrahydroabietic acid. Polymers containing the vinyl ester of dehydroabietic acid can be readily crosslinked with peroxide. 相似文献
17.
Abstract 1,5-Dioxepan-2-one was polymerized with stannous 2-ethylhexanoate as initiator and gave high molecular weight polymers, with MW > 150,000. The highest molecular weight was achieved at 110°C, and full conversion was reached after 20 hours. The polymerization rate increased with temperature. Transesterfication reactions and thermal degradation occurred above 130°C, which led to a decrease of the molecular weight. Polymerization with anion and cationic initiators led to low molecular weight polymers. Degradation of poly(1, 5-dioxepan-2-one) took place by the hydrolysis of ester bonds, and the initial molecular weight decreased by 30% during 46 weeks, starting from MW = 45,000. 相似文献
18.
Frederick C. Prehn Jr Brian D. Etz Daniel Price Amanda Trainor Caleb J. Reese Shubham Vyas Stephen G. Boyes 《Journal of polymer science. Part A, Polymer chemistry》2020,58(17):2407-2422
A detailed investigation into the role of initiator structure, the presence of an initiator, and basicity of the non-nucleophilic base in the chain-growth condensation (CGC) synthesis of poly(N-octyl benzamide) was conducted. A series of phenyl ester dimethyl amide initiators with different leaving groups were synthesized and used in the CGC preparation of poly(N-octyl benzamide). Additional polymerizations were conducted without the presence of an initiator and with different non-nucleophilic bases. Kinetic studies, along with nuclear magnetic resonance spectroscopy and gel-permeation chromatography, were used to determine progress of the reaction, molecular weights, and molecular weight distributions. The experimental and computational results demonstrated that initiators containing electron-withdrawing substituent phenyl esters, such as the p-nitrophenyl ester, and electron-withdrawing carbonyl character on the parent benzoate produce polymers with controllable molecular weights and narrow molecular weight distributions. Whereas, initiating species that contain electron-donating character on the benzoate backbone, such as dimethylamino and methyl ester groups, produce polymers that resemble the results from reactions involving no initiators at all, indicating poor polymerization control. 相似文献
19.
Shohei Inoue Takuzo Aida Masakatsu Kuroki Hiroshi Sugimoto 《Macromolecular Symposia》1992,64(1):151-158
A novel catalyst system composed of aluminium porphyrin and an organoaluminium compound with bulky substituents brings about high-speed living polymerizations of epoxide, lactone, and methacrylic ester to give the polymers with controlled molecular weight. 相似文献
20.
Devamani Srividhya Sundaram Manjunathan Sivashankaran Nithyanandan Subramanan Balamurugan Sengodan Senthil 《高分子科学》2009,(6):761-770
Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(I) yielded target polyesters with 1,2,3-triazole groups.The structure of the polymer was confirmed by spectral techniques.GPC analysis reveals that the polymers have moderate molecular weight with narrow distributio... 相似文献