对称型双端过渡态丁二烯／苯乙烯嵌段共取的性能研究

采用以双卤代烷取代型双锂齐聚物为引发剂、环已烷为溶剂、丁二烯（B）、苯乙烯（S）单体一次加入的方法，合成了对称型双端过渡成丁二烯／苯乙烯嵌段共聚物S－（S／B）－B－（B／S）－S，并对其性能进行了研究。结果表明，对称型双端过渡态丁二烯／苯乙烯嵌段共聚物具有明显的海岛两相结构，嵌段共聚物存在两个玻璃化温度；随着单体配比（质量比）S／B的增大，嵌段共聚物的各项物理性能变化趋势不明显。     

克拉顿公司SBS和SIS涨价

美国克拉顿聚合物公司自2008年6月1日起,上调北美和南美地区的嵌段共聚物产品售价。苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）和充油的苯乙烯-丁二烯-苯乙烯嵌段共聚物（O／E SBS）每吨上调330美元,或每磅上调15美分。     

科腾SBS和SIS涨价

据美国《橡胶世界》报道,由于原材料、能源和包装成本前所未有的持续上涨,美国科腾（Kraton）聚合物公司自2008年6月1日起,上调北美和南美地区的嵌段共聚物产品售价。苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）和充油的苯乙烯-丁二烯-苯乙烯嵌段共聚物（O／E SBS）每吨上,调330美元,或每磅上调15美分。苯乙烯-异戊二烯-苯乙烯嵌段共聚物（SIS）每吨上调220美元,或每磅上调10美分。     

对称型双端过渡态丁二烯/苯乙烯嵌段共聚物的研制Ⅱ.结构研究

以双锂为引发剂、环乙烷为溶剂,合成了对称型双渡态丁二烯／苯乙烯（Ｂ／Ｓ）嵌段共聚物Ｓ－（Ｓ／Ｂ）－Ｂ－（Ｂ／Ｓ）－Ｓ,并对其结构进行了研究。结果表明：随着Ｓ／Ｂ的增大、极性添加剂（２Ｇ）／Ｌｉ的增加,嵌段共聚物中苯乙烯含量增加;嵌段共聚物具有微观相分离结构,分子量分布约为１．２。     

2017年全球SBS需求量达190万t

苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）是以苯乙烯、丁二烯为单体的三嵌段共聚物,兼有塑料和橡胶的特性,被称为＂第3代合成橡胶＂,是苯乙烯-丁二烯嵌段共聚物（SBC）中产量最大（占70%以上）、成本最低、应用较广的一个品种。     

宁波科源公司投资建设SBS装置

8月26日．宁波科源石化公司宣布将在宁波清兹化工园区投资建设7万吨／年SBS（苯乙烯-丁二烯-苯乙烯嵌段共聚物）生产装置,以及贮存设施、原材料预处理装置和沥青生产装置。     

苯乙烯系热塑性弹性体及其注射重叠成型

苯乙烯系热塑性弹性体（以下简称TPES）主要是指由苯乙烯链段（S）为硬段、丁二烯链段（B）或乙烯／丁烯链段（EB）为软段的三嵌段或多嵌段共聚物SBS和SEBS的复合物。     

苯乙烯—甲基丙烯酸叔丁酯三嵌段共聚物的合成及其表征

在10℃下,以萘锂为引发剂,以甲苯／THF的混合溶剂为反应介质,采用两步加料法,合成了分子量可控、分子量分布较窄（Mw／Mn≤1．20）的苯乙烯（S）-甲基丙烯酸叔丁酯（TBMA）三嵌段共聚物（PTBMA－b-PS-PTBMA）。并对所得共聚物进行了CPC、IR、1H－NMR、TC及TEM的表征。     

对称型双端过渡态丁二烯/苯乙烯嵌段共聚物的性能研究

采用以双卤代烷烃取代型双锂齐聚物为引发剂、环己烷为溶剂、丁二烯 (B)、苯乙烯 (S)单体一次加入的方法 ,合成了对称型双端过渡态丁二烯 /苯乙烯嵌段共聚物S— (S/B)—B— (B/S)—S ,并对其性能进行了研究。结果表明 ,对称型双端过渡态丁二烯 /苯乙烯嵌段共聚物具有明显的海岛两相结构 ,嵌段共聚物存在两个玻璃化温度 ;随着单体配比 (质量比 )S/B的增大 ,嵌段共聚物的各项物理性能变化趋势不明显。     

国产SEBS流变性能评价

通过对国产SEBS(氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物)流变性能进行测试．分析不同结构、不同嵌段的S／B质量比值、不同相对分子质量、不同加工温度对SEBS产品流变性能的影响．促进用户对国产SEBS性能的了解。     

P2VP-b-PS-b-PI三嵌段共聚物的RAFT合成及表征

以S-十二烷基-S’-(α,α’-二甲基-α’’-乙酸)-三硫代碳酸酯(DDMAT)为链转移剂,通过可逆加成-断裂链转移自由基聚合(RAFT)方法制备了窄分布的聚2-乙烯基吡啶。再以该聚合物为大分子链转移剂,引发苯乙烯的RAFT聚合,得到聚2-乙烯基吡啶-b-聚苯乙烯(P2VP-b-PS)的两嵌段共聚物。以P2VP-b-PS为RAFT试剂,合成聚2-乙烯基吡啶-b-聚苯乙烯-b-聚异戊二烯(P2VP-b-PS-b-PI)的三嵌段共聚物。运用1H NMR、IR和凝胶渗透色谱(GPC)等技术对产物的结构和分子量及分子量分布进行表征,采用原子力显微镜(AFM)观察三嵌段共聚物薄膜的微相分离结构。结果表明,所得三嵌段共聚物P2VP72-b-PS136-b-PI300分子量分布较窄(PDI=1.69),合成过程具有活性/可控聚合特征,聚合物薄膜经溶剂退火处理后出现了明显的微观相分离结构。     

Effect of block copolymers of various molecular architecture on the phase morphology and tensile properties of LDPE rich (LDPE/PS) blends

The emulsification efficiency of three different block copolymers consisting of hydrogenated polybutadiene (HPB) and polystyrene (PS), i.e. a pure diblock , a tapered diblock and a triblock copolymer has been compared in low density polyethylene/polystyrene (LDPE/PS) blends rich in polyethylene. The comparison relies upon the ability of these potential interfacial agents to stabilize fine phase dispersion and to promote good interfacial adhesion. Based on the phase morphology, the ultimate tensile properties and the dynamic viscosity of the modified blends, the tapered diblock copolymer is clearly the most efficient emulsifier. For instance a plateau is observed in the property-copolymer content dependence when 2 wt% tapered diblock are used compared to ca. 5 wt% in case of the pure diblock. In contrast, no plateau is observed when the triblock copolymer is used. This is assumed to result from a less quantitative localization of these two copolymers i.e. the pue diblock or the triblock at the LDPE/PS interface.     

Influence of block lengths and symmetries of block copolymers on phase behavior of polymer A/polymer B/block copolymer ternary blends

Monte Carlo simulations were used to investigate the compatibilizing effects of diblock copolymers in A/B/A-B diblock copolymer ternary blends and triblock copolymers in A/B/triblock copolymer ternary blends, respectively. The volume fraction of homopolymer A was 19% and was the dispersed phase. The simulation results show that diblock copolymers with longer A-blocks are more efficient as compatibilizers, and symmetric triblock copolymers with a shorter middle block length are easily able to bridge each other through the association of the end blocks. This kind of triblock copolymers have relatively high ability to retard phase separation as compatibilizers.     

Crosslinkable surfactants based on linoleic acid-functionalized block copolymers of ethylene oxide and ε-caprolactone for the preparation of stable PMMA latices

Amphiphilic diblock and triblock copolymers consisting of poly(ethylene oxide) (PEO) as (central) hydrophilic segment and poly(ε-caprolactone) (PCL) as hydrophobic segment(s) were prepared by ring opening polymerization. The length of the PEO segment was kept constant , whereas the length of the PCL block(s) was either 6 or 10 units for diblock copolymers and 3 or 5 units at each end for the triblock copolymers. These block copolymers were end-functionalized by esterification with linoleic acid (LA), which contains reactive double bonds. The autoxidative behavior of PEO₄₅-(CL₃-LA)₂ functionalized triblock copolymers was investigated by exposure of films to air at ambient conditions. Ninety percent of the double bonds had disappeared in 15 d and a crosslinked structure was obtained after 30 d. Critical micelle concentrations (CMC) of the crosslinkable surfactants were in the range of 0.08-0.19 mmol/l for the diblock copolymer and of 0.19-0.26 mmol/l for the triblock copolymer. The surface tension of aqueous surfactant solutions at the CMC (γ_CMC) (25 °C) varied from 47.1 to 51.4 mN/m for the diblock and from 45.6 to 48.1 mN/m for the triblock systems. For both systems CMC and γ_CMC increase with increasing HLB values. These surfactants were used in PMMA latex preparations. The latices of PMMA prepared with LA-functionalized diblock and triblock copolymers yielded narrow particle size distributions and particle sizes of 180 and 370 nm, respectively, whereas latices prepared with SDS had a particle size of 90 nm. After extraction of the latex particles with methanol, the amounts of the unextractable (either buried or copolymerized) LA-functionalized diblock and triblock copolymers found in extracted PMMA latex particles were 10 and 24% of the initial amount of surfactant added respectively. Control experiments with a stearic acid (SA) containing diblock copolymer showed that the amount of buried surfactant in PMMA latices was 6.5%. By comparing the overall latex characteristics and stability (shelf stability, freeze-thaw testing and addition of electrolyte solutions and ethanol) it was concluded that an LA-functionalized diblock copolymer (MPEO₄₅-CL₁₀-LA) gave better stabilization of PMMA latices than an LA-functionalized triblock copolymer of comparable composition and HLB value.     

A new approach in the study of tethered diblock copolymer surface morphology and its tethering density dependence

A poly(l-lactic acid)-block-polystyrene-block-poly(methyl methacrylate) (PLLA-b-PS-b-PMMA) triblock copolymer was synthesized with a crystalline PLLA end block. Single crystals of this triblock copolymer grown in dilute solution could generate uniformly tethered diblock copolymer brushes, PS-b-PMMA, on the PLLA single crystal substrate. The diblock copolymer brushes exhibited responsive, characteristic surface structures after solvent treatment depending upon the quality of the solvent in relation to each block. The chemical compositions of these surface structures were detected via the surface enhanced Raman scattering technique. Using atomic force microscopy, the physical morphologies of these surface structures were identified as micelles in cyclohexane and “onion”-like morphologies in 2-methoxyethanol, especially when the PS-b-PMMA tethered chains were at low tethering density.     

The influence of styrene–butadiene diblock copolymer on styrene–butadiene–styrene triblock copolymer viscoelastic properties and product performance

The effects of the styrene–butadiene (SB) diblock copolymer on the viscoelastic properties of styrene–butadiene–styrene (SBS) triblock copolymers were examined in both in the the neat state and within specific product applications. The addition of the SB diblock copolymer into a pure SBS triblock copolymer resulted in a significant decrease in the plateau storage modulus and a quantitative linear rise in tan delta. In a pure triblock, in which all endblocks are anchored in polystyrene domains, all entanglements are physically trapped. The SB diblock embodies untrapped polybutadiene endblocks that are able to relax stress by chain reptation through the rubbery polybutadiene matrix. The SB diblock copolymer quantitatively lowered the microphase separation temperature (MST) of the SBS triblock copolymer. These changes in linear viscoelastic behavior manifest themselves into a reduction in the efficiency and performance of the SBS triblock copolymer in asphalt pavement binders and hot-melt adhesive blends. Specifically, the SB diblock diminished the complex shear modulus and elasticity of a polymer-modified asphalt, which translated into lower predicted rutting specification values. The increase in diblock content altered the viscoelastic response of the hot-melt adhesive blend, translating into a reduction in the shear holding power and shear adhesion failure temperature. The lack of network participation, coupled with the relaxation of the polybutadiene endblocks, accounts for the lower strength and greater temperature susceptibility of the diblock-containing systems. © 1995 John Wiley & Sons, Inc.     

Thermoreversible gelation of mixed triblock and diblock copolymers in n-octane

The thermoreversible gelation of blends of polystyrene-block-poly(ethylene/butylene)-block-polystyrene (SEBS) and polystyrene-block-poly(ethylene/propylene) (SEP) copolymers in n-octane was studied. The solvent is selective for the polyolefine blocks of the copolymers. The influence of the composition of the hybrid gels on the sol-gel transition and on the mechanical properties of the gels was analyzed. The sol-gel transition temperature increased with the concentration of both type of copolymers and did not depend on the hybrid gel composition for SEBS2 proportions higher than 50% at a total copolymer concentration higher than 6 wt%. The mechanical properties of the different gels were examined through oscillatory shear and compressive stress relaxation measurements. The elastic storage modulus increased with the triblock copolymer concentration but kept almost constant with the diblock copolymer concentration for SEBS concentrations higher than 5.0%. The stress relaxation rate was not dependent on the concentration of triblock and diblock copolymers, but the hybrid gels show lower stress relaxation rates than the pure SEBS2 gels. In the hybrid SEBS/SEP gels the SEP chains impart stability to the micelles or nodes of the network whereas the SEBS chains are responsible for the bridges that keep the gel as one-phase system.     

荧光法研究PSt-b-PCA-b-PSt与牛血清白蛋白的相互作用

采用可逆加成-断裂链转移聚合方法(RAFT)合成了聚苯乙烯-b-聚肉桂酸-b-聚苯乙烯两亲性三嵌段聚合物(PSt-b-PCA-b-PSt),采用荧光光谱法研究了PSt-b-PCA-b-PSt与牛血清白蛋白的相互作用。结果表明,PSt-b-PCA-b-PSt在选择性溶剂中自组装形成半径约为50nm的胶束;根据Stern-Volmer方程计算得到双分子猝灭过程速率常数、结合常数和结合数,表明三嵌段聚合物PSt-b-PCA-b-PSt与牛血清白蛋白之间发生了较强的静态荧光猝灭作用。     

Viscoelastic properties of a styrene-isoprene-styrene triblock copolymer and its blends with polyisoprene homopolymer and styrene-isoprene diblock copolymer

The effects of added polyisoprene homopolymer (PI) and polyisoprene-blockstyrene diblock copolymer (SI) on the viscoelastic properties of a polystyrene-block-polyisoprene-block-polystyrene triblock copolymer (SIS) having a spherical domain morphology have been examined. The former two species are used to model the effects of imperfections in structures that result from triblock copolymers missing, respectively, two or one polystyrene end blocks. The results indicate that the loss modulus and tangent delta in the plateau region can be dominated by imperfections in the copolymer structure. The interpretation of viscoelastic data in the rubbery plateau region as an indication of interface structure in block copolymers is therefore greatly complicated. Small angle X-ray scattering (SAXS) and rheological tests were also used to determine the order-disorder transition temperature for an SIS triblock copolymer and its blend with an SI diblock. The SAXS data are consistent with Han's rheological criteria for determining the order-disorder transition temperature. However, the complex viscosity does exhibit Newtonian behavior for low rates at the highest temperatures, even though the domain morphology persists. Stress relaxation and dynamic modulus data at high temperatures clearly show a secondary “rubbery” plateau at long times, and we offer a qualitative explanation for this feature based on a proposed relaxation mechanism.     

Micelles and networks formed by symmetric triblock copolymers in dilute solutions that are poor solvents for the terminal blocks

Summary A simulation for symmetric triblock copolymers in dilute solution shows a rich variety of structures when the solvent produces a net attractive interaction between the terminal blocks. Depending on the strength of this interaction, the system can form transitory aggregates, large independent micelles, or branched structures in which bridging soluble internal blocks connect dense particles formed by the aggregation of insoluble terminal blocks. The formation of the branched structure with the ABA triblock copolymer can be seen under conditions where the corresponding AB diblock copolymer would provide steric stabilization for a polymer colloid.