MDI和HMDI聚氨酯脲模型化合物的红外光谱研究

以二苯基甲烷-4，4′-二异氰酸酯（MDI）、二环己基甲烷二异氰酸酯（HMDI）和扩链剂乙二胺（EDA）和2，4-二氨基-3，5-二甲硫基氯苯（DDSCB，商品名TX-2）以及聚醚二元醇PTMG为原料，采用溶液法分别合成出了4种聚醚型聚氨酯脲（PUU）模型化合物，研究了其红外谱图，并对模型化合物的红外谱图进行比较。研究结果说明MDI型PUU的NH戍氢键的状态要强于HMDI型BUU，而MDI型多嵌段PUU模型化合物的羰基戍氢键的情况刚好相反，MDI型PUU的羰基与NH戍氢键状态和HMDI型PUU相比要较弱：而且酰胺Ⅲ与NH/C=O氢键有更大的关系，而酰胺Ⅱ带与醚氧／NH氢键有更大的关系；当氢键的受体只有羰基和醚氧基时，NH更易于和醚氧形成氢键。     

含有机硅三元嵌段共聚物及其共混物的形态结构与性能

以聚苯醚（ＰＰＯ）作为硬段、聚对羟基苯乙烯（ＰＨＳ）为半硬段、聚二甲基硅氧烷（ＰＤＭＳ）为软段，利用羟基与硅胺基缩合生成硅醚的不可逆反应，合成了含有硬段、半硬段和软段的ＰＰＯ－ＰＨＳ－ＰＤＭＳ三元嵌段共聚物。并使ＰＰＯ－ＰＨＳ－ＰＤＭＳ三元嵌段共聚物与其均聚物进行共混。研究了ＰＰＯ－ＰＨＳ－ＰＤＭＳ及其共混物的２结构和性能。结果表明，该共聚物其ｔｇδ随温度变化的曲线在－１００－２１５℃范围内是一个     

聚四氢呋喃醚二醇/聚氧化丙烯二醇共混聚醚聚氨酯弹性体的氢键作用

分别以聚四氢呋喃醚二醇(PTMG)、聚氧化丙烯二醇(PPG)及两者共混物PTMG/PPG作为软段,以2,4-甲苯二异氰酸酯(TDI-100)和扩链剂3,3'-二氯-4,4'-二氨基二苯甲烷(MOCA)作为硬段,采用预聚体法,制备了5种PTMG/PPG不同配比的浇注型聚氨酯弹性体。通过红外分析、差示扫描量热分析、动态力学热分析着重研究了PTMG/PPG不同配比对聚氨酯弹性体氢键的影响。结果表明,随着PPG型预聚体在混合预聚体中的含量增加,聚氨酯中羰基区总氢键度及脲羰基氢键度变化不大,氨酯羰基氢键度呈现先增加后减小的趋势;氨酯羰基氢键解离活化能变大,氢键趋于完善;硬段相长程有序结构熔融焓减小,脲羰基氢键完善程度下降。     

硬段模型化合物对聚氨酯型固体电解质的影响

以聚醚聚氨酯，高氯酸钠和硬段模型化合物为组分，制备了一系列新型的聚合物固体电解质，利用FT-IR，DSC，TG及复阻抗谱分析对该体系进行了表征。结果表明，当盐浓度保持恒定时，硬段模型化合物对所研究体系的形态，离子-聚合物间相互作用，玻璃化转变温度，软段热分解温度和离子导电特性的有显著的影响。随着硬段模型化合物含量的增加，体系中钠离子与醚氧基团间的络合程度增加。玻璃化转变温度和软段热分解温度上升，聚氨酯硬段的聚集体出现。所有这些均导致该固体电解质的电导率下降。     

异佛尔酮二异氰酸酯基聚醚聚氨酯弹性体的热行为

采用熔融预聚二步法合成了以环氧乙烷－四氢呋喃无规共聚醚为软段，异佛尔酮二异氰酸酯和1，4－丁二醇为硬段的热性聚氨酯弹性体，利用DSC，DMA和TG对聚合物的热行为进行了研究。结果表明，异佛尔酮二异氰酸酯基聚醚聚氨酯弹性体具有典型的微相分离特征，随着硬段含量的增加,微相分离程度增加。     

对苯二酚—双（β—羟乙基）醚扩链聚醚型聚氨酯的 …

分别用对苯二酚－双（β－羟乙基）醚（ＨＱＥＥ）和１,４－丁二醇（ＢＤＯ）作扩链剂,采用本体一步法合成几种不同硬段含量（０￣５０％）的二苯苛甲烷－４,４’－二异氰酸酯／聚四亚甲基醚二醇的聚醚聚氨酯,借助ＤＳＣ和ＩＲ等手段分析该聚氨酯的结晶性以及氢键行为,最后主为ＨＱＥＥ扩链聚醚型聚氨酯的微相分离程度较高,这是由其形成的硬链段刚性较强所致。     

扩链剂对MDI型聚氨酯结构与性能的影响

扩链剂类型对聚氨酯（PU）的结构性能有较大影响。分别采用1,4-丁二醇（BDO）、对苯二酚二羟乙基醚（HQEE）、3,3’-二氯-4,4’-二氨基二苯基甲烷（MOCA）和封端二苯基甲烷二胺（S-MDA）为扩链剂,制备了聚四氢呋喃醚二醇（PTMG）/MDI型PU弹性体。通过红外光谱、差示扫描量热法、动态力学热分析及热重分析等方法,研究了扩链剂结构对PU微相分离及性能的影响。结果表明,胺类扩链剂生成的脲基有利于硬段间形成强氢键,软硬段间微相分离程度更大,提高了硬段结晶度、力学强度和耐热性,降低了软段玻璃化转变温度和损耗因子。     

傅里叶变换红外光谱衰减全反射谱研究聚氨酯和聚脲

用傅里叶变换红外光谱(FTIR)衰减全反射谱(ATR)研究了溶液聚合的四种模型嵌段聚氨酯(聚氨酯-氨酯、聚脲-氨酯、聚氨酯-脲和聚脲-脲)。用ATR谱说明了在硬段微区和硬段微区软段微区的相界面区,不同键对这些聚合物热性质和力学性质的影响,并详细讨论了ATR谱的羟基C=O、醚氧键C—O—C、酰胺Ⅱ谱带及氢键的情况。     

聚氨酯脲的表面组成及结构

用ＡＴＲ－ＦＴ－ＩＲ和ＸＰＳ研究了聚氨酯脲以及聚二甲硅氧烷改性聚氨酯脲的表面组成和结构,发现与空气接触面和与模板接触面含有的ＰＤＭＳ和聚四亚甲基醚软段浓度远远大于其体体浓度,并且与空气接面比与模板接触面含有更多的ＰＤＭＳ和ＰＴＭＯ段。将聚酯脲水合至３个星期,其表面组成和氢键未发生任何变化。     

含叔胺基聚氮酯的结构与力学性能

讨论了以聚环氧丙烷为软段，二苯基甲烷－４，４‘－二异氰酸酯，Ｎ－甲基二乙醇胺和１，４－丁二醇为硬段，不同ＭＤＥＡ含量的含叔胺基聚氨酯的合成。用ＭＤＳＣ，拉伸试验研究了ＭＤＥＡ含量对ＮＰＵ结构与力学性能的影响。结果表明，ＭＤＥＡ引入ＮＰＵ主链，使硬段微区的内聚能以及软，硬段的相分离程度降低；材料的拉伸强度下降，伸长率增加。     

反应注射成型(聚氨酯-聚苯乙烯)间充复合弹性体的热性能研究

通过ＤＳＣ、ＴＧ考察了反应注射成型（聚氨酯－聚苯乙烯）间充复合弹性体各相态间的相互作用及其热降解规律。结果表明，ＰＵＲ交联密度提高有利于其软段相与ＰＳ相形成部分互溶的微相结构，而ＮＣＯ／ＯＨ的提高则促进软段的微相分离及增大ＰＳ与ＰＵＲ的相容性。该共混体系的热裂解属无规热降解反应，不同热裂解温度区域内各相态的热失重均有所偏重。     

Effect of glycerol cross-linking and hard segment content on the shape memory property of polyurethane block copolymer

Effect of glycerol cross-linking and hard segment content on the shape memory property of polyurethane block copolymer is comprehensively investigated. Phase separation of hard and soft segment is dependent on glycerol cross-linking and hard segment content as judged from FT-IR and DSC data. Hydrogen bonding and dipole–dipole interaction between hard segments provides strong interaction between copolymer chains in addition to chemical cross-linking by glycerol. As the hard segment content increases, the copolymer shows better tensile mechanical properties and higher melting temperature of soft segment (T _m). Effect of glycerol cross-linking on mechanical properties and T _m of soft segment is low compared to hard segment effect. Although XRD peak at 2θ = 19.5° is observed, clear difference between the copolymers with various hard segment and cross-linking content is not observed. Significant increase in shape recovery rate in the case of 30 wt% hard segment copolymer is observed after glycerol cross-linking. The drastic change of the properties of polyurethane block copolymer is discussed in the point of copolymer chain interaction.     

Structure-property relationships of polyurethanes based on toluene di-isocyanate

Eight series of polymers containing 2, 4 toluene di-isocyanate (2, 4 TDI) or 2, 6 TDI, butanediol and 1000 or 2000 molecular weight polyether or polyester soft segment were prepared, and their thermal transitions and structures studied by differential scanning calorimeter, thermo-mechanical analysis, infra-red spectroscopy and X-ray methods in order to obtain the effect of compositional variables on transition behaviour, the extent of phase segregation, and polymer properties. Results indicate that polyester soft segment contributes to greater phase mixing than the polyether, even competing with crystallization of 2, 6 TDI hard segment. This implies that hydrogen bonding of urethane NH to polyester is stronger than to polyether. In weakly phase-segregated samples, hydrogen bonding in the mixed phase raises the T _g beyond the value predicted from the copolymer equation and i.r. estimates of the degree of phase mixing. The additional increase in T _g can be accounted for by treating hydrogen bonding as cross-links. The results also indicate the effectiveness of increased polyether soft segment molecular weight in promoting phase segregation while less pronounced molecular weight effects occur with polyester soft segment. Thermal behaviour of hydrogen bonding suggests that the cause of hydrogen bond dissociation bears little relation to the state of structural organization.     

RIM—PUR／PS间充复合弹性体的结构与性能研究

报导了采用反应注射成型制备ＰＵＲ／ＰＳ间充复合弹性体，并通过ＩＲ、ＤＳＣ、ＳＥＭ研究了该材料的氢键作用及其相态结构。结果表明，所得制品呈较理想的多相微区结构，各相之间存在部分互溶，ＰＵＲ仍保持较强的氢键作用，由此提出了该材料的相态结构模型。并推知软段的柔顺性为材料提供了优良的高弹性能而材料的高强度则源于硬段微区及ＰＳ微粒的自增强作用以及ＰＵＲ强的氢健艇。     

The structure,microphase-separated morphology,and property of polyurethanes and polyureas

The structure–morphology–property relationship of thermoplastic polyurethanes and polyureas was reviewed. The effect of hard segment structure and chemistry, and the hydrogen bonding on the morphology and properties of polyurethanes elastomers was presented. Special attention was made on polyureas with strong bidentate hydrogen bonding, and they are important candidates for thermoplastic elastomers with processibility by careful selection of the hard segment symmetry and hydrogen bonding capacity.     

催化剂对异佛尔酮二异氰酸酯制备的脂肪族聚氨酯弹性体结构和性能的影响

采用一步法通过异佛尔酮二异氰酸酯与聚丙二醇和1,4-丁二醇反应合成了脂肪族聚氨酯（PU）弹性体。考察了催化剂的种类和含量对PU弹性体结构和性能的影响。结果表明,以辛酸亚锡为催化剂时,PU弹性体的软段相和硬段相间的相分离程度最明显且分子量最低,导致其力学性能最差;以辛酸铋为催化剂时,PU弹性体软段相和硬段相的相容性较好且...     

聚氨酯/ZnO纳米复合材料的制备和性能

采用原位聚合法制备了聚氨酯(PU)/ZnO纳米复合材料。DSC和FT-IR测试结果表明,PU/ZnO纳米复合材料中的氨酯羰基氢键化程度和硬段的有序化程度较纯PU低,而且PU/ZnO纳米复合材料中PU软硬段间有更好的相混合程度;TEM照片显示,ZnO以纳米尺寸较均匀地分散在PU体系中,且纳米ZnO粒子与PU基体有较强的界面作用;力学性能测试结果表明,少量纳米ZnO粒子的加入,对PU有很好的增强和增韧效果。     

聚硅氧烷-聚脲多嵌段共聚物形态结构的研究

本文采用广角X光衍散(WAXD)表征了在聚硅氧烷软段引入极性氰丙基对聚脲硬段结晶性能的影响。并进一步利用小角X光散射(XAXS)研究了软段极性基团对改善两相相容性的作用以及聚脲硬段分子量对相分离的影响。 结果表明,聚(氰丙基、甲基)硅氧烷聚脲的两相相容性较聚二甲基硅氧烷聚脲有明显改善,两相界面区域增加。随着两相相互作用加强,“硬段微畴”趋于减小且分散均匀,硬段结晶性随软段极性基团的引入而下降。     

红外二向色性法研究聚氨酯薄膜的取向行为

采用红外二向色性法对聚四氢呋喃醚二醇／４,４′－二苯基甲烷二异氰酸酯系氨酯薄膜样品的拉伸聚向行为进行了研究,结果表明,随着拉伸倍率的增大,ＣＨ２角色团发生取向。当拉伸倍率大于８０％时,NH基团也发生取向,即在外力作用下,软链段较易取向,向硬链段的取向较难。同时发现,在拉伸过程中,聚氨酯大分子中的氢键受到破坯。     

Tough Hydrogels with Fast,Strong, and Reversible Underwater Adhesion Based on a Multiscale Design

Hydrogels have promising applications in diverse areas, especially wet environments including tissue engineering, wound dressing, biomedical devices, and underwater soft robotics. Despite strong demands in such applications and great progress in irreversible bonding of robust hydrogels to diverse synthetic and biological surfaces, tough hydrogels with fast, strong, and reversible underwater adhesion are still not available. Herein, a strategy to develop hydrogels demonstrating such characteristics by combining macroscale surface engineering and nanoscale dynamic bonds is proposed. Based on this strategy, excellent underwater adhesion performance of tough hydrogels with dynamic ionic and hydrogen bonds, on diverse substrates, including hard glasses, soft hydrogels, and biological tissues is obtained. The proposed strategy can be generalized to develop other soft materials with underwater adhesion.