PPO-PDMS-PHS_n三元多嵌段共聚物的形态结构和性能

利用DMA,TEM和SAXS对以聚苯醚(PPO)为硬段、聚对羟基苯乙烯(PHS)为半硬段和聚二甲基硅氧烷(PDMS)为软段的三元多嵌段共聚物(?)PPO-PDMS-PHS(?)_n的形态结构和性能进行了研究.结果表明,(?)PPO-PDMS-PHS(?)_n以三种嵌段相容相为连续相,PPO与PHS的相容相和PDMS相为两种分散相,其tanδ随温度变化曲线在-100℃至200℃一直是一很高的平台,并具有优异的力学性能,较好地解决了含有机硅类嵌段共聚物强度低的弱点,同时又保留了嵌段共聚物微相分离的特性.     

[-PPO-PDMS-PHS-]n三元多嵌段共聚物的形态结构和性能

利用DMA, TEM和SAXS对以聚苯醚(PPO)为硬段、聚对羟基苯乙烯(PHS)为半硬段和聚二甲基硅氧烷(PDMS)为软段的三元多嵌段共聚物[-PPO-PDMS-PHS-]n以三种嵌段相容相为连续相, PPO与PHS的相容相和PDMS相为两种分散相, 其tan δ随温度变化曲线在-100℃至200℃一直是一很高的平台, 并具有优异的力学性能, 较好地解决了含有机硅类嵌段共聚物强度低的弱点, 同时又保留了嵌段共聚物微相分离的特性。     

聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物的微相分离与结晶

本工作研究了多分散和单分散聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物(PEO-PS-PEO)的结晶行为,及这些试样按非晶型嵌段共聚物进行微相分离后再结晶的结晶特点.     

聚合物链长及表面吸附强度对三维受限下嵌段共聚物微观相分离的影响

利用动态密度泛函(Dynamic density functional theory, DDFT)方法研究了三维受限下嵌段共聚物的微观相分离, 讨论了共聚物链长和表面吸附强度对微观相形成与取向的影响. 体系中随机分布的等径微球提供三维限制结构, 体积分数为0.6. 增加微球的半径和体积分数, 能够使其从破坏微相规整结构的纳米掺杂过渡到提供三维限制结构. 调整嵌段共聚物与微球表面的相互作用对微相形成与取向有重要影响.     

聚苯乙烯/聚二甲基硅氧烷嵌段共聚物的表面形态研究

采用原子力显微镜(AFM)和透射电镜(TEM)研究了聚苯乙烯/聚二甲基硅氧烷嵌段共聚物(PS-b-PDMS)薄膜的相形态.结果表明,当采用甲苯作为溶剂,旋转涂膜的薄膜样品呈现网络状的形态分布在表面,而样品所对应的透射电镜照片中,PDMS相作为球状分布在PS的连续相中.退火温度对共聚物表面形态有一定的影响,当退火温度高于PDMS的玻璃化温度,表面中PDMS相增多.PS-b-PDMS嵌段共聚物的表面形态随着所用溶剂的变化而有所不同,当采用甲苯作为溶剂时,样品的PS相形成凹坑分布在PDMS的相区之中,而采用环己烷作为溶剂时,PS相作为突起分布在PDMS相区之中.另外,基底对共聚物薄膜表面形态的有较大的影响,当采用硅晶片作为基底时,样品中的PDMS相和PS相呈现近似平行于表面的层状结构.     

嵌段共聚物薄膜中条纹形态的螺旋结构

利用溶液滴膜的方法在云母表面制备聚苯乙烯-聚异戊二烯-聚苯乙烯(SIS)三嵌段共聚物薄膜, 用原子力显微镜(AFM)观察其表面形态. 发现共聚物经微相分离, 在薄膜中形成平行于表面的条纹形态, 相周期约(38±5) nm, 并且观察到条纹环绕形成的螺旋图案, 图案尺寸超过1 μm. 在螺旋中心某一组分形成闭合端, 而其它区域条状相沿螺旋切线方向平行排列. 嵌段共聚物溶液成膜过程中, 螺旋图案的产生是由于微相分离过程耦合流体力学相互作用产生的不稳定性所导致.     

嵌段共聚物苯乙烯-丁二烯-苯乙烯(SBS)/苯酰化聚苯醚共混分相动力学

<正> 对高分子-高分子共混体系相分离动力学过程的研究,人们一般局限于均聚物-均聚物,均聚物-无规共聚物共混体系,对于均聚物-嵌段共聚物共混体系的分相过程很少涉及。原因其一是很难找到具有临界相行为的嵌段共聚物-均聚物共混体系,其二是嵌段共聚物存在微相分离,使得宏观相分离动力学过程研究变得复杂。Paul的工作似乎为这方面的研究工作开辟了道路。     

聚四氢呋喃-聚甲基丙烯酸甲酯两嵌段共聚物的结晶行为

报导了系列聚四氢呋喃-聚甲基丙烯酸甲酯结晶-非晶(硬段型)两嵌段共聚物的结晶行为，结果表明，其微相分离和结晶规律与文献上唯一进行过系统研究的同类嵌段共聚物(PEO－b－PS)都有较大的差别；结晶段结晶能力的大小是制约这类体系微相分离和结晶规律的一个重要因素．     

动态密度泛函理论在嵌段共聚物介观结构模拟中的应用

采用动态密度泛函理论(DDFT)方法对两嵌段和三嵌段共聚物熔体微相分离后的三维介观结构进行了模拟研究,考察了共聚物链长．N—12下组分A、B不同配比的11种两嵌段共聚物和10种三嵌段共聚物,通过等密度面图很好地表述了微相分离后的三维介观结构。通过比较序参数户、自由能F和熵S随时间的变化,发现当组分A与组分B的链节数之比．NA／NB和模拟参数均相同时,两嵌段共聚物熔体比三嵌段共聚物熔体容易发生微相分离,而三嵌段共聚物越不对称,微相分离越容易。     

显式溶剂模型模拟嵌段共聚物在纳米微滴中的图案化结构

采用耗散粒子动力学(DPD)方法研究了嵌段共聚物在纳米微滴中的相分离行为.模拟是将共聚物纳米微滴置于溶剂环境中进行自发相分离,从而形成一些图案化结构.由于是受限体系,所形成的结构和在溶液或熔融体中形成的相分离结构有所差异,这些结构的形成与亲/疏溶剂嵌段比例(RH/T)有关系.随着亲/疏溶剂嵌段比例的增加,依次形成了枣糕球体、排球状相、多层囊泡(洋葱相)、笼状相、纳米杆状相和分散胶束等结构.我们对洋葱相的形成过程进行了详细的描述.溶剂粒子的集群属性有助于更加深入地了解洋葱相的结构衍化.采用密度曲线分析了洋葱相的结构.在较高的亲/疏溶剂嵌段的比例条件下,嵌段共聚物主要表现为亲溶剂性,通过吸收大量的溶剂溶胀形成疏松结构或瓦解形成分散的胶束悬浮在溶剂中.本文模拟结果与理论或实验结果基本吻合.     

MICROPHASE SEPARATED STRUCTURES AND PROPERTIES OF PDMS-MDI-PEG COPOLYMER SURFACE

A series of poly(dimethylsiloxane)(PDMS)-4,4′-diphenylmethanediisocyanate(MDI)-poly(ethylene glycol)(PEG) multiblock copolymers were synthesized by employing two-step growth polymerization and investigated by AFM,XPS. contact angle system,protein adsorption and platelets adhesion measurements,respectively.It was found that as the molecular weight of PDMS increased,the surface of copolymers had increasing phase separation,while the increase in the molecular weight of PEG decreased the phase separation ext...     

Ideal tetrafunctional amphiphilic PEG/PDMS conetworks by a dual‐purpose extender/crosslinker. I. Synthesis

The synthesis of a new type of amphiphilic conetwork (APCN) consisting of well‐defined hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) segments is described. The conetwork is ideal (the lengths of each PEG and PDMS chain segments, respectively, are identical) and tetrafunctional (exactly four chains emanate from each crosslink site). The synthesis of the conetworks was achieved by the use of a novel dual‐purpose extender/crosslinker Y (bis [(dimethylsilyl)oxy]‐[(etoxydimethylsilyl)oxy]phenylsilane, (SiPh(SiH)₂OEt)), in two steps: (1) Synthesis of a new linear random multiblock copolymer (MBC) (AY)_n(BY)_m, where A is the hydrophilic PEG and B is the hydrophobic segment, and (2) Crosslinking the multiblocks by catalytic condensation of the SiOEt groups in the Y units. The extender/crosslinker fulfills two totally different functions: First, it extends two incompatible hydrophilic and hydrophobic prepolymers (PEG and PDMS) to a random MBC, and, subsequently, it cross‐links the multiblocks to the target APCN. The synthesis and characterization of the extender/crosslinker is also presented. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4953–4964, 2005     

Synthesis and surface properties of environmentally responsive segmented polyurethanes

Polyurethanes, containing well-defined assemblies of perfluoro-polyether (PFPE or hexafluoropropene oxide oligomer), polydimethylsiloxane (PDMS), and polyethylene glycol (PEG) segments, exhibit oleophobic, hydrophobic, and hydrophilic properties in response to the polarity of the contacting medium. These polymers were prepared by reacting hydroxy(polyethyleneoxy)-propylether-terminated PDMS block copolymer (HO-PEG-PDMS-PEG-OH) with 4,4'-methylene-bis(phenylene isocyanate) (MDI) in the presence of dibutyltin dilaurate catalyst, followed by reaction with 1,2-diol functional PFPE and chain extension with 2,2,3,3-tetrafluoro-1,4-butanediol (FB). The oleophobic and hydrophobic properties of the segmented polyurethanes (SPU) are due to the segregation of PFPE segments at the polymer-air interface. Wettability studies revealed that the same surface becomes hydrophilic, presumably due to the segregation of the PEG segments at the polymer-water interface. This hydrophobic-to-hydrophilic transformation of the surface prevails not only when the polymer is in contact with liquid water but with water vapor as well. The understanding of the reconstruction mechanism of this novel family of SPU surfaces would furnish valuable information for various applications where dynamic transformation of surface activity is desired.     

Effect of annealing on the microphase separated behavior and properties of PDMS–MDI–PEG multiblock copolymer films

A model multiblock copolymer based on (Poly dimethylsiloxane) (PDMS),–4, 4′‐diphenylmethanediisocyanate (MDI)–(poly ethylene glycol) (PEG) was synthesized by employing two step growth polymerization technique. The effect of annealing on microphase separation of the copolymer surface and bulk, surface composition, hydrogen‐bonding and some properties was investigated by AFM, SAXS, XPS, FTIR, contact angle measurement, and protein adsorption experiment, respectively. It was found that increasing the annealing temperature availed formation of microphase separation and surface enrichment of PDMS, which was accompanied by increase in average interdomain spacing, long period, and the crystallizing degree in the hard domains. But the best microphase separated structure seemed to occur at the annealing temperature of 140 °C; exorbitant annealing temperature might demolish the ordered structure. The annealing temperature dependence of microphase separation was further confirmed by the changes in urea hydrogen‐bonding and melting points characterized by FTIR and DSC, respectively. Protein adsorption experiments revealed that all annealed copolymer films possessed the low protein adsorption. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 208–217, 2007     

Synthesis and characterization of (AB)n-type poly(l-lactide)-poly(dimethyl siloxane) multiblock copolymer and the effect of its macrodiol composition on urethane formation

An (AB)_n-type multiblock copolymer containing alternating poly(l-lactide) (PLLA) and poly(dimethyl siloxane) (PDMS) segments was synthesized by chain extension of hydroxyltelechelic PLLA-PDMS-PLLA triblock copolymers, which were prepared by the ring-opening polymerization of l-lactide initiated by α,ω-functionalized hydroxyl poly(dimethyl siloxane), using 1,6-hexamethylene diisocyanate as a chain extender. The triblock and the multiblock copolymers were characterized by FT-IR, ¹H NMR and GPC. From the results of thermal analysis, two glass transition temperatures which were measured by DSC showed the occurrence of phase separation phenomena in the triblock and multiblock copolymers because of the difference of solubility parameters between PLLA and PDMS segments. The effect of the chemical composition of the triblock copolymers, including the Mw and the constitutive segment chain length of the macrodiol, on the development of the Mw of the multiblock was discussed based on diffusion effect. Furthermore, the consumption of the isocyanate groups was determined by FT-IR to investigate the dependence of the reaction kinetics of the urethane formation on the chemical composition of the triblock copolymer. The results reveal that the order of the chain extension reaction depended on the Mw of the triblock copolymer: a second order reaction was transformed into a third reaction as the Mw of the triblock copolymer increased from 7000 to 25,000 (g/mol) perhaps because of the inhibition of the formation of an active complex involved in the catalyzed-urethane reaction by the polymer chain aggregation. Finally, the mechanical properties of the multiblock copolymers demonstrated that the introduction of the extremely flexible PDMS segment substantially improved the elongation at breakage, and the tensile strength and the tensile modulus declined due to the intrinsic elasticity of such segments.     

Novel amphiphilic triblocks fitted with photocrosslinkable termini,and their photocrosslinking to conetworks

Two new telechelic amphiphilic triblock copolymers, HE₃‐PEG‐b‐PDMS‐b‐PEG‐HE₃ and HE₃‐PEG‐b‐PDMS‐b‐PEG‐HE₃, i.e., sequence‐reversed triblocks of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) segments fitted with photocrosslinkable tri[2‐(3,4‐cyclohexane oxide)ethyl‐dimethylsiloxy]silane (HE₃) termini, were synthesized, characterized, photocrosslinked to amphiphilic conetworks (APCNs), and the properties of the APCNs were analyzed. APCNs in which the crosslinking sites are located in the hydrophobic domains exhibited significantly better mechanical properties than those in which the crosslinks were in the hydrophilic domains. The stiff domains formed of the UV‐crosslinkable HE₃ chain‐end substituents provide not only crosslinking but reinforcement as well. The crosslinking/reinforcement efficiency was greatly enhanced by the addition of excess HE₃. Water‐swollen APCNs were optically clear and exhibited mechanical properties appropriate for biomedical application. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 174–185, 2008     

含聚氧化乙烯嵌段的三元多嵌段共聚物的合成和性能

用聚乙二醇、聚丙二醇、遥爪羟基聚苯乙烯和二氯甲烷在氢氧化钾存在下合成了氧亚甲基连接的聚氧化乙烯－聚氧化丙烯－聚苯乙烯多嵌段聚合物；并研究其乳化性能和相转移催化性能。     

Multiblock copolymers of poly(2,5‐benzophenone) and disulfonated poly(arylene ether sulfone) for proton‐exchange membranes. I. Synthesis and characterization

Nanophase‐separated, hydrophilic–hydrophobic multiblock copolymers are promising proton‐exchange‐membrane materials because of their ability to form various morphological structures that enhance transport. A series of poly(2,5‐benzophenone)‐activated, telechelic aryl fluoride oligomers with different block molecular weights were successfully synthesized by the Ni(0)‐catalyzed coupling of 2,5‐dichlorobenzophenone and the end‐capping agent 4‐chloro‐4′‐fluorobenzophenone. These telechelic oligomers (hydrophobic) were then copolymerized with phenoxide‐terminated, disulfonated poly(arylene ether sulfone)s (hydrophilic) by nucleophilic, aromatic substitution to form hydrophilic–hydrophobic multiblock copolymers. High‐molecular‐weight multiblock copolymers with number‐average block lengths ranging from 3000 to 10,000 g/mol were successfully synthesized. Two separate glass‐transition temperatures were observed via differential scanning calorimetry in the transparent multiblock copolymer films when each block length was longer than 6000 g/mol. Tapping‐mode atomic force microscopy also showed clear nanophase separation between the hydrophilic and hydrophobic domains and the influence of the block length as it increased from 6000 to 10,000 g/mol. Transparent and creasable films were solvent‐cast and exhibited moderate proton conductivity and low water uptake. These copolymers are promising candidates for high‐temperature proton‐exchange membranes in fuel cells, which will be reported separately in part II of this series. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 284–294, 2007     

Synthesis and properties of multiblock copolymers based on polydimethylsiloxane and polyamides from dicarboxylic acid and diisocyanate terminated functionalities

Polydimethylsiloxane (PDMS)–polyamide multiblock copolymers were successfully synthesized via diisocyanate route by two different procedures, i.e., the one-step and two-step methods, In the two-step method, α, ω-diisocyanate-terminated polyamide oligomers, which were prepared in situ from a mixture of isophthalic acid (IPA) and azelaic acid (AZA) with 4,4′-methylenedi (phenyl isocyanate) (MDI) in 1,3-dimethyl-2-imidazolidone (DMI) in the presence of 3-methyl-1-phenyl-2-phosopholene 1-oxide catalyst, were reacted with α, ω-bis (10-carboxydecyl) polydimethylsiloxane (PDMS-diacid) leading to the formation of multiblock copolymers. In the one-step method, the reaction components, MDI, IPA, AZA, and PDMS-diacid were reacted all together in DMI in the presence of the catalyst. These polymerizations gave multiblock copolymers having inherent viscosities in the range of 0.36–1.12 dL/g in N,N-dimethylacetamide (DMAc). These multiblock copolymers were soluble in amide-type solvents, and transparent (or translucent) and ductile films could be cast from the solutions in a mixture of DMAc and bis(2-ethoxyethyl) ether. The multiblock copolymers prepared by the two-step method had better-defined, microphase-separated morphology than those obtained by the one-step method. The mechanical properties of PDMS–polyamide multiblock copolymer films were found to be highly dependent on the PDMS content; the tensile strength and modulus of the films decreased with increasing the PDMS content.     

含氟/PEG的有机硅基双亲防污涂层的制备及性能

以不同分子量的端氢硅油(PDMS)和聚乙二醇二烯丙基醚(PEGDE)为原料,通过硅氢加成合成了系列双键封端的含有机硅和聚乙二醇(PEG)链段的多嵌段共聚物(PDMS-b-PEG)m,再用三甲氧基氢硅烷进行端基官能化,生成三甲氧基硅烷封端的多嵌段聚合物,即含PEG前驱物.含PEG前驱物、含氟前驱物(FMS-9922)与有机硅基体树脂通过缩合聚合制备了含PEG的氟硅双亲弹性防污涂层.通过核磁共振氢谱、红外光谱对PEG前驱物的结构进行了表征.吸水率、SEM-EDS和接触角测试考察了含PEG前驱物中疏水链段的长度,含氟前驱物的含量对涂层表面重排的影响,结果表明PEG前驱物中疏水链段越长,涂层的吸水率越低,在水中越稳定,且表面不易发生重排.而含氟前驱物的加入能促使PEG链段向表面方向迁移.抗蛋白、抗菌和抗藻附着性能测试表明:含有FMS-9922的样品防污性能均优于不含FMS-9922的样品,而且随着FMS-9922用量增加,涂层防污性能呈上升趋势;但是FMS-9922用量太高时,体系相容性下降,防污性能也随之变差,故FMS-9922的含量控制在7%为宜.