Poly(epsilon-caprolactone)/poly(ethylene oxide) diblock copolymer .1. Isothermal crystallization and melting behavior

The isothermal crystallization and melting behavior of the poly(epsilon-caprolactone) (PCL)/poly(ethylene oxide)(PEO) diblock copolymer has been studied by WAXD, SAXS, and DSC methods. Only the PCL block is crystallizable; the PEO block of weight fraction 20% cannot crystallize, although its corresponding homopolymer has strong crystallizability. The long period, amorphous layer, and crystalline lamella of the PCL/PEO block copolymer all increase with the rise in the crystallization temperature, and the thickness of the amorphous layer is much larger than that of crystalline lamella due to the existence of the PEO block in the amorphous region. The isothermal crystallization of the PCL/PEO block copolymer is investigated by using the theory of Turnbull and Fischer. It is found that the amorphous PEO block has a great influence on the nucleation of PCL block crystallization, and the extent of this influence depends on crystallization conditions, especially temperature. The outstanding characteristics are the phenomenon of the double melting peaks in the melting process of the PCL/PEO block copolymer after isothermal crystallization at different temperatures and the transformation of melting peaks from double peaks to a single peak with variations in the crystallization condition. They are related mainly to the existence of the PEO block bonding chemically with the PCL block. In summing up results of investigations into the crystallization and melting behavior of the PCL/PEO block copolymer, it is interesting to notice that when the PCL/PEO block copolymer crystallizes at three different crystallization temperatures, i.e., below 0 degrees C, between 0 and 35 degrees C, and above 35 degrees C, the variation of peak melting temperature is similar to that of overall crystallization rates in the process of isothermal crystallization. The results can be elucidated by the effect of the PEO block on the crystallization of the PCL block, especially its nucleation. (C) 1996 John Wiley & Sons, Inc.

NMR-STUDY ON THE RELATIONSHIP BETWEEN MISCIBILITY AND ANTIAGING PERFORMANCE OF BLENDS CONTAINING BLOCK-COPOLYMERS

The anti-aging performance of blends of polystyrene (PS), styrene-butadiene triblock copolymers (SBS), and PS/styrene-butadiene (SB)-4A (Carm star SE block copolymer) has been studied by means of C-13 NMR techniques. It is found that the anti-aging performance of these kinds of blends largely depends on their miscibility with PS of different molecular weight M(PS). The larger the quantities of PS solubilized in polybutadiene (PBD) domains, the better the anti-aging performance of the blends. It is also found that the anti-aging performance of these blends has dependence on molecular architectures of the SE block copolymers. For the aged blends, the double bonds of PBD were broken, meanwhile serious cross-linking networks formed in the blends. The proposed anti-aging mechanism is that the PS solubilized in PBD domains can efficiently prevent oxygen molecules from diffusing into PBD domains, therefore, successfully stop the oxidative process of PBD.

COMPATIBILITY AND CRYSTALLIZATION OF TETRAHYDROFURAN-METHYL METHACRYLATE DIBLOCK COPOLYMER/POLYTETRAHYDROFURAN BLENDS

The compatibility and crystallization of tetrahydrofuran-methyl methacrylate diblock copolymer (PTHF-b-PMMA)/tetrahydrofuran homopolymer (PTHF) blends were studied. Our results showed that the crystallization and morphology of compatible PTHF-b-PMMA/PTHF

Crystallization Behavior of Poly(tetrahydrofuran-b-methyl methacrylate) Diblock Copolymer

Crystallization behavior of a series of newly synthesized poly (tetrahydrofuran-b-methyl methacrylate) diblock copolymer has been studied by differential scanning calorimetry (DSC) and X-ray scattering and diffraction techniques. The results show that the

THE COMPATIBILITY AND CRYSTALLIZATION OF THE MIXTURES OF POLY (TETRAHYDROFURAN-b-METHYL METHACRYLATE) DIBLOCK COPOLYMER WITH POLYVINYL CHLORIDE HOMOPOLYMER

The compatibility and crystallization behaviour of the mixtures of poly (tetrahydrofuran-methyl methacrylate) diblock copolymer (PTHF-b-PMMA) with polyvinyl chloride has been studied. We found that the compatibility of these blends, in which there is special interaction between the homopolymer and the PMMA block of the copolymer, is much better than that of the AB/A type blends; and that the crystallization rate and crystallinity of PTHF microdomain changed greatly due to the swollen by PVC homopolymer. In this paper, these changes in cryatallization are well explained according to the theories of block copolymer blends and the density gradient model presented by JIANG Ming.

RELATIONSHIP BETWEEN CRYSTALLIZATION OF THE PDMS BLOCK AND MORPHOLOGY OF POLY(BUTADIENE-B-DIMETHYLSILOXANE)

Studies using transmission electron microscopy, differential scanning calorimetry, and X-ray diffraction showed correlations between the crystallization behavior of the polydimethylsiloxane (PDMS) block and the morphology of the block copolymer poly (butadiene-b-dimethylsiloxane) (PB-PDMS). When the PDMS component existed as spheres dispersed in a PB matrix, the crystallization rate of the PDMS block was lower than when the PDMS phase existed in rod or cylinder form.

PS-b-PEO嵌段共聚物薄膜的结晶与微相分离

半结晶性嵌段共聚物中，嵌段间的不相容性导致的微相分离与结晶嵌段的结晶行为之间存在相互竞争与协同作用。现阶段的大部分工作主要集中于半结晶性嵌段共聚物相分离发生后的结晶行为的结晶动力学和内部链折叠，而对于结晶与微相分离同时发生时的结晶与微相分离行为的研究还较少。 本论文以半结晶性的聚苯乙烯和聚环氧乙烷的二嵌段共聚物（PS-b-PEO）薄膜为研究对象，研究其破坏性（break out）结晶行为，以及研究方形片晶与微相分离结构的关系。 首先，本论文研究了不同相分离取向对结晶行为的影响。我们通过控制膜厚得到垂直基底和平行基底的微相分离薄膜。在溶剂蒸汽中，微相分离取向垂直基底时，仅仅是有序度增加，片晶协同生成。退火时间增加，结晶成核控制生长向扩散控制生长转变，导致片晶周围树枝晶生长。微相分离结构为平行基底取向时，焓主要用于取向转变和有序度增加，体系没有片晶生成，仅边缘效应使树枝晶产生。在结晶取向方面，研究了溶剂蒸汽氛围内界面作用改变使分子链轴垂直基底（flat-on）结晶向分子链轴平行基底（edge-on）结晶的转变。随着溶剂分子扩散到基底界面，结晶嵌段PEO与基底相互作用从强变弱，是发生这种转变的决定因素。 其次，从片晶与微相分离相互转变和片晶上微相分离刷的形成两方面研究片晶与微相分离的竞争与协同关系。退火溶剂的选择性影响片晶与微相分离的竞争。在PEO不良溶剂蒸汽环己烷中发生以下转变：片晶生成，逐渐被微相分离破坏，片晶重新生成；PEO良溶剂水中仅存在结晶到微相分离的转变。即晶体溶解，与PS发生微相分离以获得能量上的有利状态。可溶解嵌段的自由体积增加和结晶嵌段的低溶胀性分别是微相分离和结晶发生的关键因素。片晶与微相分离协同关系研究上，通过调控二嵌段共聚物片晶上聚合物刷的密度（小于14.3大于3.8），获得具有微相分离结构的聚合物刷。PS-PS刷的弱相互作用以及PS与PEO（连接PEO片层结构未结晶的PEO链）之间的强不相容性对片层上微相分离刷的形成起来决定作用。

溶剂诱导嵌段共聚物薄膜的微观相分离

通过研究发现薄膜厚度、溶剂对不同链段的选择性以及溶剂蒸汽处理时间对嵌段共聚物薄膜表面形态的演变有重要影响。对于对称双嵌段共聚物（PS-b-PMMA）薄膜在薄膜厚度小于0.5L_o时，在PMMA的选择性溶剂中处理不同时间时，除了得到垂直的lamellae形态外，还得到了有序纳米孔洞以及有序纳米孔洞和片层共存的新形态。同时其表面组成发生了变化，由最初PS位于表面层而转变为PMMA位于表面层。更进一步，得到的纳米结构图案化的薄膜具有环境敏感性。当将其置于对PS嵌段具有选择性的溶剂蒸汽中时，表面形貌发生了反转。另外研究发现，二元双嵌段共聚物共混体系，即小分子量的PS-b-PMMA和大分子量的PS-b-PMA共混，在硅基底上发生自组装形成具有有序孔洞结构的薄膜。这种结构完全不同于某一组分单独存在时所形成的微相结构。根本原因在于PMA和PMMA嵌段化学结构上的相似性，使PMMA链部分嵌入能量上优先吸附于极性基底的PMA嵌段中，形成了两种分子中的PS相容在一起构成的连续相围绕着塌陷的PMMA相的形态。

聚苯乙烯-聚丁二烯嵌段共聚物反转相行为的研究

本论文以聚苯乙烯（PS）一聚丁二烯（PB）三嵌段和二嵌段共聚物体系为研究对象，利用聚合物的软有序化，控制聚合物分子链的取向和聚集条件，系统地考察了嵌段共聚物在由溶液成膜的过程中动力学效应和墒效应对其相结构和相转变行为的影响。并探讨了不同相结构和其力学性能之间的构效关系。设计了聚苯乙烯（PS）一聚丁二烯（PB）（PS≈30wt％）／非选择性溶剂体系，通过改变溶剂的挥发速率，控制了嵌段共聚物薄膜相结构形成的动力学过程。在快速挥发的条件下，在嵌段共聚物中观察到了特殊的反转相结构，即共聚物中含量多的组分（PB）形成了分散相，而当溶剂挥发很慢的条件下，得到的是热力学较稳定的正常相的结构。对不同分子量的一系列嵌段共聚物的研究表明，反转相的形成和分子量相关，与聚合物的链段数目无关，只有在低于临界分子量 （Mw=70-100 KDa）的嵌段共聚物中，成膜过程的动力学过程才影响嵌段共聚物薄膜的最终相态，即形成反转相。这种依赖于分子量的相转变行为，揭示了分子链运动速度与环境变化速率的匹配对嵌段共聚物薄膜有序相结构形成的重要作用，即动力学效应对聚合物软有序化的重要作用。利用冷冻干燥的方法，进一步研究了嵌段共聚物在极慢的溶剂挥发下，由溶液膜变成固体膜的过程中，随着溶液浓度的增加，不同聚合物分子链在溶液中自组织形成有序结构的过程。结果表明反转相是由稀溶液向亚浓溶液转变的过程中形成的。通过选取具有代表性的不同亲和性的溶剂：苯和环己烷及其混合溶剂，研究了溶剂对不同链段亲和性的差异对反转相形成的影响。由聚合物一溶剂相互作用参数判断，苯是体系的良溶剂，环己烷是体系的。溶剂，而苯对PS链段有较好的亲和性，与之相反环己烷对PB链段有较好的亲和性，通过对聚苯乙烯（PS）一聚丁二烯印B）二嵌段共聚物在苯和环己烷极其混合溶剂中的相转变行为的研究发现，随着溶剂对含量少的PS链段亲和性的降低，反转相不再出现。这是由于苯与PS．链段、环己烷与PB链段有更好的亲和性，嵌段共聚物在稀溶液中，在耗尽吸引的（depletion attraction）作用下，与溶剂亲和性弱的链段，在溶液中优先发生聚集，而有序聚集后导致的混合熵的损失会被更多的因有序聚集后小分子自由体积增加引起的平移嫡的增量所补偿，因此导致了嫡驱动的软有序化。最后，通过原子力显微镜纳米压印法，分别对反转相和正常相结构的纳米力学性能进行了对比研究，讨论了不同相结构间模量的差异，结果表明软段（PB）形成分散相结构时薄膜的模量总是小于硬段（PS）形成分散相结构时薄膜的模量，这主要是由嵌段共聚物不同组分的相对含量及形成的相的结构决定的。

Crystallization and morphology of poly(ethylene oxide-b-lactide) crystalline-crystalline diblock copolymers

The crystallization behaviors and morphology of asymmetric crystalline-crystalline diblock copolymers poly(ethylene oxide-lactide) (PEO-b-PLLA) were investigated using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and microscopic techniques (polarized optical microscopy (POM) and atomic force microscopy (AFM)). Both blocks of PEO5-b-PLLA(16) can be crystallized, which was confirmed by WAXD, while PEO block in PEO5-b-PLLA(30) is difficult to crystallize because of the confinement induced by the high glass transition temperature and crystallization of PLLA block with the microphase separation of the block copolymer.

Molecular weight dependence of phase Behavior of PEO/P(EO-b-DMS) blends: Application of Sanchez-Lacombe lattice fluid theory

Molecular weight dependence of phase separation behavior of the Poly (ethylene oxide) (PEO)/Poly(ethylene oxide-block-dimethylsiloxane) (P(EO-b-DMS)) blends was investigated by both experimental and theoretical methods. The cloud point curves of PEO/P(EO-b-DMS) blends were obtained by turbidity method. Based on Sanchez-Lacombe lattice fluid theory (SLLFT), the adjustable parameter, epsilon*(12)/k (quantifying the interaction energy between different components), was evaluated by fitting the experimental data in phase diagrams. To calculate the spinodals, binodals, and the volume changes of mixing for these blends, three modified combining rules of the scaling parameters for the block copolymer were introduced.

Aliphatic Poly(ester-carbonate)s Bearing Amino Groups and Its RGD Peptide Grafting

This article deals with (1) synthesis of novel cyclic carbonate monomer (2-oxo [1,3]dioxan-5-yl)carbamic acid benzyl ester (CAB) containing protected amino groups; (2) ring-opening copolymerization of the cyclic monomer with L-lactide (LA) to provide novel degradable poly(ester-carbonate)s with functional groups; (3) removal of the protective benzyloxycarbonyl (Cbz) groups by catalytic hydrogenation to afford the corresponding poly(ester-co-carbonate)s with free amino groups; (4) grafting of oligopeptide Gly-Arg-Gly-Asp-Ser-Tyr (GRGDSY, abbreviated as RGD) onto the copolymer pendant amino groups in the presence of 1,1'-carbonyldiimidazole (CDI).

Synthesis and characterisation of novel functional polyolefin containing sulfonic acid groups

The strong polar group, sulfonic acid, has successfully been introduced into ethylene/allylbenzene copolymers without degradation or crosslinking via chlorosulfonation reaction with chlorosulfonic acid as a chlorosulforiating agent in 1, 1,2,2-tetrachloroethane followed by hydrolysis. The degree of sulforiation (DS) can be easily controlled by changing the ratio of chlorosulfonic acid to the pendant phenyls of the copolymer. The microstructure of sulfonated copolymers were unambiguously revealed by H-1 NMR and H-1-H-1 COSY spectral analyses, which indicates that all the sulforiation reactions exclusively took place at the para-position of the aromatic rings.