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为考察溶质浓度对三碳多元醇水溶液氢键作用以及不同物质玻璃态形成能力的影响,采用1H NMR外标法研究不同浓度的1-丙醇(NPA),2-丙醇(IPA),1,2-丙二醇(PG),1,3-丙二醇(PD)和丙三醇(glycerol)的水溶液在室温常压下质子化学位移.结果表明:具有CH3CH(OH)一基团的PG烷基质子的化学位移变化趋势与其他几种醇相比有较大差异.醇羟基质子与水分子的氧形成较强O-H…O氢键.相同摩尔分数下,羟基数的增加导致水质子和羟基质子的化学位移降低,而且羟基位置不同也会导致水质子和羟基质子化学位移差异.这几种三碳多元醇碱性强弱的顺序和降低冰的均相成核温度能力的顺序一致,即glycerol>PG>PD>IPA>NPA,1H NMR技术表明glycerol和PG更适合用作低温保护剂. 相似文献
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Silvia G. Prolongo M. Burón A. Salazar A. Ureña J. Rodríguez 《Journal of Thermal Analysis and Calorimetry》2007,87(1):269-276
Blends based on epoxy resins and a random copolymer, poly(styrene-co-allylalcohol)
(PS-co-PA) were studied, analysing the effect of epoxy nature. The epoxy cross-linking
reaction was carried out by homopolymerisation, using an imidazole as initiator,
and by addition of several amine hardeners. The imidazole acts as initiator
of anionic epoxy etherification and as catalyser of epoxy-hydroxyl reaction.
Important differences were observed on the network structure and phase behaviour
of blends depending on the nature of epoxy matrix. These cause that the blends
present different morphologies and different dynamic mechanical properties. 相似文献
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Zhaozhong Jiang Siddharth Sanganeria Ayusman Sen 《Journal of polymer science. Part A, Polymer chemistry》1994,32(5):841-847
The reaction of the alternating ethylene–carbon monoxide copolymer with Lawesson's reagent resulted in the conversion of 75% of the carbonyl groups to thiophene units. A few thioketone groups were also present in the derived polymer. A polymer with furan units in the backbone was formed upon treatment of the alternating propylene–carbon monoxide copolymer with P2O5. Depending on the reaction conditions, up to 90% of the carbonyl groups were converted. Finally, 1,4-polyalcohols were prepared from the alternating propylene-carbon monoxide copolymer by reduction. Hydrogenation using Raney nickel as catalyst resulted in the reduction of 60% of the carbonyl groups, whereas reaction with LiAlH4 at room temperature caused the reduction of 85% of the carbonyl groups. The glass transition temperature was found to increase monotonically with increasing concentration of hydroxyl groups in the polymer backbone. © 1994 John Wiley & Sons, Inc. 相似文献
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Katsuhiko Takaya Chihiro Itoh Yoshiro Uunno 《Journal of polymer science. Part A, Polymer chemistry》1998,36(6):889-900
A new polymer (polyalcohol) was synthesized by hydrogenation of an ethylene carbon monoxide (CO) copolymer produced by a radical method with a catalyst and H2. The Ru/α-alumina catalyst systems showed an excellent activity for hydrogenation of the radical copolymer of CH2CH2 and CO. Films prepared by melting and pressing the synthesized polyalcohol had a high gas barrier property and high tensile modulus. This new polymer has hydroxymethylenic units [ CH(OH) ] and ethylenic units [ CH2CH2 ] in its molecular structure. The new functional polymer poly(hydroxymethylene-co-ethylene), [ CH(OH) ]n[ CH2CH2 ]m , is amorphous and has excellent and important properties as a high oxygen gas barrier film for wrapping and storage. This may be attributed to the new structure of poly(hydroxymethylene-co-ethylene) (PHME as an IUPAC name), or ethylene methine alcohol copolymer (EMOH as a generic name), compared to the other ethylene vinyl alcohol copolymer (EVOH as a generic name), [ CH2CH2 ]m [ CH2CH(OH) ]n , which is used as one of the highest gas barrier polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 889–900, 1998 相似文献
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De-Biao Huo Ji-Dong Leng Jing Wang Zi-Zhou Wang Wan-Ming Lu Xiao-Shuo Hong 《Journal of Coordination Chemistry》2017,70(5):936-948
Two mixed-valence Mn(II,IV) complexes, [MnII4MnIV3(teaH)3(tea)(thmeH)3(thme)](ClO4)2·3MeCN (1) and [MnII2MnIV2(edteH)2(peolH)2]·4MeOH (2), where H4edte = N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine, teaH3 = tris(2-hydroxyethyl)amine, H4peol = pentaerythritol, and H3thme = 1,1,1-tris(hydroxymethyl)ethane, were prepared from the corresponding manganese salts and mixed ligands with polyalcohols. The two clusters consist of a trapped-valence polynuclear core comprising 4MnII and 3MnIV for 1, 2MnII and 2MnIV ions for 2. Complex 1 crystallizes in the rhombohedral space group R3c, while 2 crystallizes in the monoclinic space group P21/c. Complex 1 consists of a near-planar Mn7 unit that comprises a Mn6 hexagon of alternating MnII and MnIV ions surrounding a central MnII ion. The remaining coordinated sites are occupied by eight different deprotonation degrees of H3tea or H3thme. The tetranuclear cluster of 2 consists of a fused defective dicubane Mn4O6 core, and the four Mn ions are coordinated by oxygens from edteH3? and peolH3? into an unusual butterfly-like [MnII2MnIV2] topology. The two clusters are also characterized by mass spectra and X-ray photoelectron spectroscopy. Direct current magnetization studies reveal ferromagnetic interactions within both Mn clusters. 相似文献
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