丁腈橡胶标准物质的~1H-NMR表征

应用1H -NMR技术对系列丁腈橡胶 (BNR)标准物质的结构进行了表征。测定了丁腈橡胶标准物质中聚丁二烯链段中的顺式和反式结构含量、聚丁二烯链段中 1,4加成聚合与 1,2加成聚合的含量以及丁腈橡胶标准物质中结合丙烯腈的含量     

丁腈橡胶标准物质的^H—NMR表征

应用＾１Ｈ－ＮＭＲ技术对系列丁腈橡胶（ＢＮＲ）标准物质的结构进行了表征。测定也丁腈橡胶标准物质中聚丁二烯链段中的顺式和反式结构含量、聚丁二烯链段中１，４加成聚合与１，２，加成聚合的呈以及丁腈橡胶标准物质中结合丙烯腈的含量。     

不同氢化度氢化丁腈橡胶的结构表征与分子模拟

通过核磁共振波谱(¹H NMR)、 红外光谱(IR)及热分析等方法研究了不同氢化度氢化丁腈橡胶(HNBR)分子结构之间的差异, 结果表明, 在丁腈橡胶(NBR)加氢过程中, 聚丁二烯上的乙烯基加氢速率最快, 其次是反式1,4结构, 顺式1,4结构的加氢速率最慢, 而腈基基本不发生氢化反应. 采用核磁共振谱法对不同氢化度HNBR中不同链段的含量进行定量分析, 依据此结果建模并进行分子模拟计算, 得到不同氢化丁腈橡胶的密度、 内聚能密度(CED)和玻璃化转变温度(T_g)等参数, 模拟值与实验结果吻合. 实验结果表明, 随着氢化度的增加, HNBR的热氧化稳定性逐渐增加, 这主要是由于氢化度增加后分子链中双键含量逐渐减少而CED增加的缘故. 分子模拟可以有效地计算出多种结构参数, 为共聚橡胶材料的制备与加工提供基础数据及理论指导.     

聚丁二烯1,2-结构含量和SBS中聚丁二烯段1,2-结构含量的调节

以正丁基锂为引发剂,环己烷为溶剂,研究了四氢呋喃(THF)对聚丁二烯1,2-结构和丁苯嵌段共聚物SBS中聚丁二烯段1,2-结构含量的影响,指出在一定温度下,聚丁二烯1,2-结构含量与体系中THF的浓度有指数关系。控制体系中THF的浓度和聚合反应温度,可调节聚合产物中聚丁二烯1,2-结构含量。     

裂解色谱法(PGC)分析聚丁二烯分子链结构

近年来热裂解色谱法(PGC)发展不断完善,已成为高分子结构分析的有力手段。利用PGC法对聚丁二烯分子链结构的研究已有很多报导。庄野曾提出用VCH/BD(克分子比)表征聚丁二烯分子链中1,4-结构的含量;Perry通过对1,2-和1,4-结构的聚丁二烯热裂解反应研究,建议用C_2/BD表征聚丁二烯分子链中1,2/1,4结构克分子比。但由于方法的     

线型聚芳醚砜-聚醚氨酯嵌段共聚物的合成及其结构性能的初步探讨

<正> 具有抗凝血性和其它一些特殊性能的聚醚氨酯嵌段聚合物,最近颇受注视。本文以异氰酸酯的氢转移加成聚合反应为主的合成方法,在聚合物的主链中引入具有一定结构的其它链段组份,合成了一类新的线型聚芳醚砜-聚醚氨酯嵌段共聚物。并就其结构与性能的关系进行了初步探讨。     

以高顺式聚丁二烯为软段的三嵌段共聚物的制备

从高顺式端羟基聚丁二烯(HTPB)出发,分别以ε-己内酯和苯乙烯为单体合成了2类以高顺式聚丁二烯为软段的三嵌段共聚物.以高顺式HTPB为大分子引发剂、辛酸亚锡为催化剂,引发ε-己内酯的开环聚合,合成了聚己内酯-b-聚丁二烯-b-聚己内酯三嵌段共聚物(CLBCL);通过高顺式HTPB末端羟基与2-溴代异丁酰溴(BBi B)间的酯化反应制备了ATRP大分子引发剂(Bi B-PB-Bi B),进而引发苯乙烯进行电子转移活化再生催化剂原子转移自由基聚合(ARGET ATRP)反应,合成了聚苯乙烯-b-聚丁二烯-b-聚苯乙烯三嵌段共聚物(SBS),反应具有较好的可控性,产物分子量分布较窄.通过红外光谱(FTIR)、核磁共振氢谱(1H-NMR)和碳谱(13CNMR)、热重分析(TGA)和示差扫描量热分析(DSC)等对所制备共聚物的结构和性能进行了测试表征.TGA曲线表明,提高聚己内酯链段的含量,可在一定程度上提高CLBCL共聚物的热稳定性;SBS共聚物的热分解过程表现为一个阶段,与HTPB相比,其热稳定性略有提高.从CLBCL共聚物的DSC曲线上可明显观察到聚丁二烯链段的玻璃化转变温度和聚己内酯链段的熔点;SBS共聚物具有2个玻璃化转变温度,为–104.1和102.4oC,分别对应于聚丁二烯链段和聚苯乙烯链段的玻璃化转变温度.     

线性/三臂星型端羟基聚丁二烯的活性负离子聚合及其表征

在环己烷溶剂中,以自制的叔丁基二甲基硅氧基丙基锂为引发剂,丁二烯为单体,四氢呋喃为结构调节剂,采用活性负离子聚合法合成了线形端羟基聚丁二烯(L-HTPB).在此基础上,以甲基三氯硅烷为偶联剂合成了星形端羟基聚丁二烯(S-HTPB).采用GPC和1H-NMR对L-HTPB和S-HTPB结构进行了表征,结果表明,采用负离子聚合法合成的2种聚合物具有相同的微观结构,且线形端羟基聚丁二烯的平均官能度大于1.9,星形端羟基聚丁二烯的平均支化度和平均官能度大于2.8,与理论设计值基本相符.另外,实验中通过调节溶剂中环己烷和四氢呋喃的比例来控制聚合物主链的微观结构.实验结果证实,随复配溶剂中环己烷用量的增加,聚合物1,4-结构相对含量逐渐增大,特别是顺式1,4-结构相对含量增大的趋势比较明显;当聚合溶剂采用单一的环己烷时,聚合物主链1,4-结构相对含量大于90%,顺式1,4-结构相对含量高达70%以上,聚合物主链中1,2-结构相对含量约为5.70%;相反,当聚合溶剂采用单一的四氢呋喃时,聚合物主链1,2-结构相对含量大于90%,而顺式1,4-结构相对含量趋于0,样品的外观表现为塑料.     

辐射交联顺1,4-聚丁二烯的NMR研究

用１３Ｃ ＮＭＲ方法,测定了辐射交联顺１,４ 聚丁二烯在室温下的自旋 晶格弛豫时间（Ｔ１）,核Ｏｖｅｒｈａｕｓｅｒ因子（ＮＯＥ）,和１３Ｃ ＮＭＲ线宽．以及凝胶本体１Ｈ ＮＭＲ的Ｔ１和Ｔ２弛豫时间,结果表明,辐射交联顺１,４ 聚丁二烯体系中,随着凝胶含量的增加各碳核质子的Ｔ１值变化很小,而—ＣＨ２—核的ＮＯＥ因子明显降低和１３Ｃ ＮＭＲ线宽增宽．以及１Ｈ ＮＭＲ的Ｔ１和Ｔ２表现的双指数弛豫特性反映了交联体系中大分子链段长程运动受阻以及饱和交联叔碳核—ＣＨ对链段运动的影响．     

含反-1,4聚丁二烯链段的顺-1,4聚丁二烯橡胶的合成、鉴认和性能

顺-1,4聚丁二烯橡胶是合成橡胶中的第二大品种,具有耐磨、生热低等优点,是轮胎胎面胶的重要组成部分。本工作研究了含量少反-1,4聚丁二烯链段的顺-1,4丁二烯橡胶的合成、鉴认及其生胶、母胶和硫化胶的性能。     

NMR and DSC investigations of the miscibility of blends of cis-1,4-polyisoprene with polybutadienes of different microstructures

Differential scanning calorimetry and torsional braid analysis investigations of the phase diagram of cis-1,4-polyisoprene/polybutadiene blends as a function of the polybutadiene microstructure were reported by several authors. Polybutadienes containing a high vinyl content were shown to be miscible with cis-1,4-polyisoprene on the DSC spatial scale, whereas polybutadienes containing a low vinyl content were immiscible. In this article, we used variable-temperature determinations of ¹H NMR free induction decays and low-temperature, high-resolution solid-state ¹³C NMR measurements of proton spin-lattice relaxation times in the rotating frame to probe the phase behavior of the cis-1,4-polyisoprene/polybutadiene blends at the smaller spatial scale of the NMR technique. Blends of cis-1,4-polyisoprene with a polybutadiene having a large number of vinyl 1,2 linkages appeared to be miscible on the molecular scale, in spite of small regions in which the polybutadiene component is not uniformily dispersed in the other polymer. On the contrary, blends in which the polybutadiene has a low content of vinyl 1,2 sequences were phase separated over the whole temperature range considered and no intermixed regions could be detected. The limiting case was observed with the polybutadiene containing 33 wt % vinyl 1,2 units, for which miscibility on a molecular scale is highly dependent on the blend composition. © 1995 John Wiley & Sons, Inc.     

溶聚丁苯链化学结构的NMR研究

溶聚丁苯链化学结构的NMR研究;溶聚丁苯; 链化学结构; 相容性     

裂解色谱法测定环化顺1,4聚丁二烯的环化度

用裂解色谱法研究了不同环化度的环化顺１，４聚丁二烯，建立了测定ＣＰＢｄ环化度方法，分析了不同实验条件下生成的ＣＰＢｄ的环化度，结果与ＮＭＲ测定值一致。     

Assignment of the relative configuration of spiro[4.5]decanes by 13C, 15N and 17O NMR

The relative configuration of 11 1,4-diazaspiro[4.5]decanes (1a-1j and 1m), 15 1,4-oxazaspiro[4.5]decanes (2a-2o) and 10 1,4-dioxaspiro[4.5]decanes (3a-3n) substituted at the 2-, 6-, 7- or 8-position by a methyl group or using the tert-butyl group as a model for the ananchomeric structure is reported. The relative stereochemistry was analyzed by 1H, 13C, 15N and 17O NMR and all isomers present were characterized spectroscopically. Compounds with a methyl group in the six-membered ring show a chair conformation preference with the methyl group in the equatorial position. Compounds with one or two nitrogens exhibit a tautomeric equilibrium between the imine-diazolidine forms, as demonstrated by IR and 13C NMR.     

Structural characterization of polybutadiene synthesized via cationic mechanism

The microstructure of polybutadiene synthesized via cationic polymerization using TiCl₄‐based initiating systems has been investigated using 1D (¹Н, ²Н, and ¹³С) and 2D (HSQC and HMBC) NMR spectroscopy. It was found that trans‐1,4‐unit is predominant structure of unsaturated part of polymer chain. Besides, the small amount of 1,2‐structures was also detected, while cis‐1,4‐units were totally absent. The signals of carbon atoms of three types of head groups (trans‐1,4‐, 1,2‐, and tert‐butyl) and two types of end groups (trans‐1,4‐Cl and 1,2‐Cl) were identified for the first time in macromolecules of cationic polybutadiene. It was showed that tert‐butyl head groups were formed due to the presence in monomer of admixtures of isobutylene. The new methodology for calculation of the content of different structural units in polybutadiene chain as well as the head and end groups was proposed. It was established that main part of 1,2‐units distributed randomly along the polybutadiene chain as separate units between trans‐1,4‐structures. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 387–398     

Characterization of diene polymers. I. Infrared and NMR studies: Nonadditive behavior of characteristic infrared bands

Extinction coefficients of the characteristic infrared bands due to isomeric structural units were measured for polybutadiene and polyisoprene in CS₂ or CCl₄ solutions and were compared with the isomer composition determined by NMR. The NMR signal assignments were made on the basis of the spectra of deutero derivatives of the polymers. In the case of polyisoprene, linear relations were obtained between the extinction coefficients and the isomer contents determined by NMR for the absorption bands at 1385 cm^?1 (characteristic of trans-1,4 units), 1376 cm^?1 (cis-1,4 units), and 889 cm^?1 (3,4 units). However, for the absorption bands at 840 cm^?1 (characteristic of cis-1,4 and trans-1,4 units), isomerized polyisoprenes did not give such a linear relationship. In polybutadiene, the extinction coefficient for the atactic 1,2 units was found to be lower than that of the syndiotactic 1,2 unit. These experimental facts lead to the conclusion that additivity of the extinction coefficients does not always hold for diene polymers. The deviation from the linear relation may be associated with regular sequences of one isomeric conformation in the chain.     

Glass-transition temperature and microstructure of polybutadienes

DSC and NMR are employed to determine the glass-transition temperatures and the structural features of polybutadienes with widely varying configuration isomeric compositions. The dependences of the glass-transition temperature on the contents of cis-1,4-, trans-1,4, and 1,2-units in polybutadiene chains are plotted and discussed. An analysis of the experimental results and the published data suggests that, in the study of the glass-transition-structure relationship, simplified approaches are inapplicable and it is necessary to consider the configurational and conformational geometry of polybutadiene chains.     

Influence of polar modifiers on microstructure of polybutadiene obtained by anionic polymerization. Part 4: Acid-base polar modifiers forming σ-μ complexes: Amine-alkoxide,amine-ether-alkoxide,and ether-alkoxide

The influence of acid-base polar modifiers (σ-μ complex): amine-alkoxide, amine-ether-alkoxide, and ether-alkoxide complexes on microstructure of polybutadiene obtained by anionic polymerization was studied. The content of butadiene isomeric structures was determined based on FT-IR-ATR, ¹H, and ¹³C NMR data analyses. The results obtained indicated a very similar influence of all types of polar modifiers forming σ-μ complex on polymer microstructure leading to high vinyl polybutadiene with nearly equal ratios of cis-1,4 and trans-1,4 butadiene isomeric structures.     

丁苯、丁腈基聚氨酯的形态与性能

用示差扫描量热法 (DSC)、红外分光光度计 (FTIR)和原子力显微镜 (AFM)研究了端羟基聚丁二烯 苯乙烯共聚物 (HTBS)、端羟基聚丁二烯 丙烯腈共聚物 (HTBN)和端羟基聚丁二烯 (HTPB)与甲苯二异氰酸酯、1 ,4 丁二醇构成的溶液法聚二烯烃基聚氨酯 (PU)的形态结构 .结果表明HTPB和HTBS基PU的相分离程度很大 ,而HTBN基PU的相分离程度小 .这可能归因于HTBS软段的极性低 ,不能与硬段形成氢键 ,而HTBN软段中的腈基具有很强的极性 ,且可以与硬段形成氢键作用 ,增加了软硬段间的相容性 ,相分离程度明显降低 .AFM表明HTBN PU随着硬段含量提高 ,表面粗糙度增大 ,由软段为连续相逐渐过渡到双连续结构 .在硬段含量 6 3%时 ,HTBN和HTPB基PU均呈双连续结构 ,而HTBS PU中硬段为连续相 .HTBN PU软段的相区尺寸在1 2nm左右 ,表面粗糙度较大 ,HPBS PU软段的相区尺寸在 1 1nm左右 ,表面粗糙度最小 ,HTPB PU存在 1 4nm和 5 0nm大小不等的软段相区尺寸 .力学性能表明 ,在软段中引入苯乙烯和丙烯腈结构 ,可使聚氨酯抗张强度分别提高 1 5和 2倍 ,模量和断裂伸长率也明显提高