聚(苯乙烯-丁二烯-苯乙烯)三嵌段共聚物链结构的研究

<正> 以丁基锂引发二步加料法制备聚(苯乙烯-丁二烯-苯乙烯)三嵌段共聚物(简称SBS),往往在共聚物的中间链段聚丁二烯段中含有少量苯乙烯,即中间链段末端含有部份无规丁苯,得不到很纯的三嵌段共聚物,本文用超导核磁共振仪(H~1-NMR)、傅立叶红外光谱仪(FT-IR)、粘弹谱仪研究了上述SBS链结构,发现非嵌段苯乙烯芳环质子共振峰由二     

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.     

SBS三嵌段共聚物在丁酮溶剂中的降解

论文研究了SBS三嵌段共聚物在选择性溶剂丁酮中的降解。采用超速离心沉降速度法、毛细管粘度法、GPC和IR的研究手段,证实了SBS/丁酮溶液存放时间较长时,溶液中SBS分子发生降解,降解发生在聚丁二烯嵌段的不饱和双键。从而也表明SBS/丁酮溶液中胶束行为的不稳定归国于SBS分子的降解。     

基团转移聚合法合成A-B型嵌段共聚物

用基团转移聚合法(GTP)合成嵌段共聚物是近年来国际上高分子研究的热门之一.在室温下制备嵌段共聚物是GTP的一大特点.本文利用三类不同GTP单体的活性差别^[1,2],控制适当的加料顺序及聚合条件,首次用GTP法合成含丙烯腈嵌段的A-B型共聚物并进行表征.     

线形苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)的粘弹弛豫与相形态

研究了不同温度下苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)的粘弹弛豫与相形态. DSC分析发现, SBS的相结构特别是其中质量分数较低的PS相畴的大小受热历史影响显著. 用TEM表征了SBS的双相连续形态和两相相畴尺寸. 用动态流变学方法研究了不同温度下SBS嵌段大分子的松弛行为. 结果表明, 在低于PS相玻璃化转变温度时, 嵌段分子中的PB段已可发生运动; 而当高于PS玻璃化转变温度后, 由于PB与PS间的相互作用及PB的链缠结所限制, 体系仍保持较高的弹性模量, 呈现“第二平台”特征流变行为.     

SBS改性沥青机理研究进展

介绍了沥青的特性、苯乙烯-丁二烯-苯乙烯三嵌段共聚物(SBS)的性能,分析了SBS与基质沥青之间的溶胀性和相容性问题,着重论述了SBS改性沥青机理的研究进展,指出机理主要分为物理共混和化学改性两类:物理共混——SBS微粒受到沥青组分中油分的作用发生溶胀而均匀分散在沥青中,SBS与沥青之间没有发生化学作用,只是一种分子间作用力;化学改性——加入添加剂使沥青和SBS之间发生加成、交联或接枝等化学反应,形成较强的共价键或离子键,改善沥青的化学性质。提出化学改性是提高SBS改性沥青路用性能的重要手段。     

分子水平研究不同嵌段结构苯乙烯/丁二烯共聚物的表面结构

利用具有准单分子层灵敏度的和频振动光谱(SFG)、原子力显微镜(AFM)和接触角(CA)测定技术研究链结构和溶剂对苯乙烯(S)/丁二烯(B)嵌段共聚物表面准分子层化学结构形成的影响.结果表明,两嵌段共聚物SB比三嵌段共聚物SBS更有利于聚丁二烯(PB)组分在膜表面富集.利用PB的选择性溶剂环己烷做溶剂时,SB膜表面层完全由纯的PB组分组成,而SBS表面则是聚苯乙烯(PS)与PB二组分共存.利用PS的选择性溶剂甲苯做溶剂时,SB与SBS表面都是PS与PB二组分共存,其中SBS表面PS组分的含量更高.原因是由于溶剂影响嵌段共聚物分子在溶液中的构象从而影响溶剂挥发后聚合物表面结构的形成.     

苯乙烯-丁二烯-苯乙烯/聚乙烯基甲基醚共混体系相容性的FT-IR及DSC研究

嵌段高聚物、均聚物共混体系相容性是近年来研究的热点。本工作以光学显微镜、DSC、FT-IR为手段,研究了三嵌段高聚物苯乙烯-丁二烯-苯乙烯(SBS);SBS-48、SBS-30,SBS-28与聚乙烯基甲基醚共混体系的相容性。DSC结果表明,随SBS中PS含量的升高,体系相容性变好,PS段分子量增大,也有助于体系相容。FT-IR结果表明PVME中COCH_3在1100cm~(-1)附近呈现的双峰的相对强度对体系的相容性十分敏感,而由于苯环C—H振动产生的698cm~(-1)峰位却不象PS/PVME体系那样随相容性的改变而有显著的改变。总而言之,嵌段高聚物SBS/均聚物PVME共混体系中,体系的相容性依赖于嵌段高聚物在体系中的组份含量及嵌段高聚物中PS的重量百分含量,PS段分子量的大小对体系相容性也有影响。     

含聚氧乙烯链段的两亲嵌段共聚物及接枝共聚物的分子设计,合成及性能

论述了由聚烯链段与聚苯乙烯或聚（甲基）丙烯酸酯链段组成的各种嵌段或接枝共聚物（包括二嵌段、两种三嵌段、星型嵌段、多嵌段、二种规整接枝共聚物等）的分子设计及合成,并总结了其两亲性质、络合碱金属离子性及微观相分离等特性。     

硫醇类配体修饰金纳米粒子在嵌段共聚物中自组装的研究进展

本文综述了不同类型硫醇配体修饰金纳米粒子的合成方法以及功能性金纳米粒子在嵌段共聚物薄膜中的自组装研究进展,重点介绍了硫醇类配体修饰金纳米粒子的合成方法,包括Brust合成法、原位合成法、grafting from合成法、配体置换法、单晶模板法等。总结了硫醇基小分子或聚合物配体修饰的金纳米粒子与嵌段共聚物之间自组装的调控方法,如利用配体与嵌段共聚物组分的隔离作用、配体与嵌段共聚物组分形成的氢键作用、溶剂蒸气退火或热退火等诱导嵌段共聚物/纳米粒子复合薄膜自组装。展望了功能性金纳米粒子以及嵌段共聚物/金纳米复合材料的发展方向。     

SBS与甲基丙烯酸丁酯本体接枝反应的研究

本文研究了以过氧化苯甲酰(BPO)为引发剂,甲基丙烯酸丁酯(BMA)既作溶剂又作为单体与苯乙烯-丁二烯嵌段共聚物(SBS)进行接枝共聚反应。用红外光谱、核磁共振谱及透射电镜表征了接枝共聚物(SBS-g-BMA)的组成及结构,讨论了时间、温度及SBS和BPO的用量对接枝的影响。     

Chemical initiation of graft copolymerization of methyl methacrylate onto styrene–butadiene block copolymer

When a solution containing both styrene–butadiene block copolymer (SBS) and methyl methacrylate is treated with an initiator both homopolymerization of the methyl methacrylate and graft copolymerization of the methyl methacrylate onto the SBS occur. The amount of graft copolymerization depends upon the time and temperature of the reaction, the concentrations of all species, and the identity of the solvent and initiator. The combination of benzoyl peroxide in chloroform gives the highest graft yield and the reaction occurs by removal of an allylic hydrogen from the SBS by the initiator radical and subsequent addition of monomer units to that site; there is a significant solvent effect. Both AIBN and BPO function by the removal of an allylic hydrogen atom from SBS; BPO is able to effect this reaction relatively easily while AIBN can remove the hydrogen atom only with great difficulty and to a limited extent. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 965–974, 1997     

两步合成法对SBS结构与性能的研究

<正> 以单官能团烷基锂为引发剂,用两步法合成苯乙烯-丁二烯-苯乙烯(SBS)嵌段共聚物文献中仅见一般性介绍,较为详细的只有Cunningham的研究报告,据认为用n-BuL(正丁基锂)为引发剂时共聚物的物性不佳。我们以环己烷为溶剂,n-BuLi为引发剂,对两步法合成SBS进行了研究。由于在系统中引入了少量THF(四氢呋喃),并找到了消除体系中微量杂质的有效方法,因而试验重复性好,产品物性优良,超过文献值而与Shell公司偶联法工业化产品相近。     

Thermal properties and morphology of α-methylstyrene-butadiene-α-methylstyrene triblock copolymer

Poly(α-methylstyrene-butadiene-α-methylstyrene) (mSBmS) was synthesized by two stages living anionic polymerization. Sodium naphthalene was used as initiator and HMPT as promoter to accelerate cross-over reactions. The microstructure and composition of mSBmS were identified by infrared and nuclear magnetic resonance spectroscopes. The domain size was roughly calculated from TEM observation. It was observed that the morphology changed with the composition. The mSBmS exhibited two T_g^s, ?4 and 172°C, that associated with polybutadiene and poly-α-methylstyrene, respectively. Comparing stress relaxation behaviors of mSBmS and styrene-butadienestyrene (SBS) at various temperatures, mSBmS showed a better thermal stability and degradation resistance than SBS. From the thermal gravimetric analysis, at 200°C, mSBmS gave a weight loss less than 1%, which provided a further evidence of better thermal stability of this material than of SBS.     

High performance poly(styrene-b-diene-b-styrene) triblock copolymers from a hydrocarbon-soluble and additive-free dicarbanionic initiator

A new hydrocarbon-soluble (additive-free) dicarbanionic organolithium initiator, obtained by a simple halogen-lithium exchange reaction (Gilman's reaction) from a diarylhalide containing a side C15 alkyl chain, has been designed and used to initiate the anionic polymerization of butadiene and styrene. The dilithiated species formed afford well-defined poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymers with a high percentage of 1,4-microstructure polybutadiene (91%) and excellent mechanical properties, such as ultimate tensile strength higher than 30 MPa and elongation at a break of 1000%. This represents a breakthrough in the synthesis of SBS polymers, one of the most used thermoplastic elastomers.     

一种新颖丙烯腈基含糖共聚物的合成和表征

利用无保护的糖内酯与甲基丙烯酸-2-氨乙基酯盐酸盐反应高效简便合成了一种新颖的直链糖,并用水相沉淀聚合的方法将其与丙烯腈进行了共聚合。考察了单体配比、聚合时间、引发剂浓度和总单体浓度对聚合行为的影响,红外、核磁用来表征聚合物,证明水相沉淀聚合是一种有效的聚合方式。     

In-situ direct polycondensation in polymer matrices. II. In-situ direct polycondensation in styrene–butadiene block copolymers

Direct polycondensation of 3-substituted-4-hydroxybenzoic acid was carried out in solutions of styrene-butadiene block copolymers (SBS) at room temperature in the presence of triphenylphosphine and hexachloroethane as an initiator for the direct polycondensation of these monomers. Solution casting after the direct polycondensation provided opaque films in which the aromatic polyester was finely dispersed within the matrix of SBS. Mechanical properties of these films were examined by tensile tests. A great improvement of tensile strength was achieved by the incorporation of phenyl substituent in the resulting polyester. In-situ direct polycondensation leads to the formation of new composites of rigid polymers and flexible polymers. © 1993 John Wiley & Sons, Inc.     

Controlled placement of polystyrene-grafted CdSe nanoparticles in self-assembled block copolymers

Surface functionalization of semiconductor CdSe nanoparticles has been achieved with polystyrene (PS) brushes by “grafting from” technique for further addition to a polystyrene-b-polybutadiene-b-polystyrene (SBS) block copolymer in order to obtain self-assembled composites. For modification of nanoparticle surface 3-glycidoxypropyltrimethoxysilane (GPS) was used at first for the later attachment of the 4,4′-azobis(4-cyanopentanoic acid) azo initiator. Fourier-transform infrared spectroscopy confirmed the presence of GPS and PS on the surface of nanoparticles. Atomic force microscopy was used for morphological characterization of SBS/CdSe nanocomposites. Modification of nanoparticles with PS brushes by radical polymerization improved their affinity with PS block and the dispersion of nanoparticles avoiding agglomeration. CdSe nanoparticle size was measured to be around 2 nm by the use of X-ray diffraction and UV–Vis techniques. Optical properties were characterized using fluorescence measurements.     

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。