聚醚酯多嵌段共聚物结晶行为研究

对硬链段具有一定分布的聚醚酯多嵌段共聚物的结晶行为进行了研究。从所得结果表明,其结晶过程可以类比于均聚物在溶液中的分级过程。软硬链段的组成决定了某一长度硬链段的丰度;而结晶条件及试样的热历史则决定了各种不同长度硬链段的超饱和程度,分聚速率和结晶速率。究竟那些长度的硬链段能结晶取决于上述两因素。     

软段和硬段结构对交联的嵌段共聚物力学阻尼及相容性的影响

本文研究了链段结构对多嵌段共聚物网的相容性及动态力学阻尼性能的影响。分别以端乙烯基低聚物作为软链段,乙烯类聚合物作为硬链段,制备了一系列具有不同链段结构共聚物网。它们在大于50℃的温度范围,能阻尼机械振动。共聚物网中某些软链段和硬链段成分是半相容的。基于这些配方的许多共聚物网,在需要的温度范围,tanδ>1.75。     

聚甲基丙烯酸胆甾醇酯共聚物的合成、结构与性能研究 Ⅳ.PMACE的相态转变及光学性质

Finkelmann和等人对侧链胆甾型高分子液晶的研究表明,将具有液晶功能的低分子基团,经过一个软段连接到柔性高分子主链上的梳型高分子在一定的温度下可以形成液晶态,调节侧链高分子液晶的分子结构、软段长度,可以改变其相态转变温度及微区形态。前已报导具有不同侧链结构的聚甲基丙烯酸胆甾醇酯共聚物的合成、相态转变及光学性质,本文通过对聚甲基丙烯酸胆甾醇乙烯酯共聚物(PMACE)的液晶态及结晶态的微细结构及相态转变与胆甾侧链含量关系的研究,给出了液晶态的形成条件及结构特征。     

长碳链聚醚酰胺弹性纤维开发及其弹性机理

以长碳链聚酰胺弹性体为原料,通过熔融纺丝技术制备了高性能化新型长碳链聚醚酰胺(LPAE)弹性纤维.该弹性体是以基于生物来源单体的长碳链聚酰胺为硬段,以聚醚为软段,其弹性可通过调节软硬段比例有效调控.测试结果表明,与目前市场上应用广泛的氨纶莱卡(LYCRA)相比,软段含量较高的LPAE纤维具有高断裂伸长,低初始模量的特点;在200%伸长范围内,其弹性回复率与氨纶相当,耐热性优于氨纶.分析得知,LPAE纤维的高弹性源于硬段聚酰胺存在强氢键相互作用且结晶度高,同时硬段充当物理交联点;软段具有良好的柔性,可以发生大变形,这种软硬段交替的嵌段分子链结构形成三维网络.大应变下,LPAE纤维弹性回复率降低是由分子链滑移及软段拉伸诱导结晶共同造成的.     

环氧树脂-聚醚-三乙烯四胺嵌段聚合物的表面活性研究

本文对含有环氧树脂分子链段、聚醚链段及三乙烯四胺链段的系列多嵌段聚合物（TETA-DGEPG-EPON828、TETA-DGEPG-EPON834及TETA-DGEPG-EPON1001加成物）进行了合成与表征。其HLB的估算值分别为16.6、15.8、13.0;浊点分别为91.0℃、89.0℃、81.0℃,它们能将水溶液表面张力从74mN•m-1降低到36.4~39.4mN•m-1。通过其理化性能的研究,结果表明TETA-DGEPG-EPON834具有优良的水溶性和良好的表面活性。选用它作为相反转乳化剂,可制备出稳定的纳米级的CARDURA E-10封端的EPON828-TETA加成物的水性环氧固化剂胺基分散体乳液。     

环氧树脂-聚醚-三乙烯四胺嵌段聚合物的表面活性

对含有环氧树脂分子链段、聚醚链段及三乙烯四胺链段的系列多嵌段聚合物(TETA-DGEPG-EPON828、TETA-DGEPG-EPON834及TETA-DGEPG-EPON1001加成物)进行了合成与表征. 其HLB的估算值分别为16.6、15.8和13.0,浊点分别为91.0、89.0和81.0 ℃. 合成物能将水溶液表面张力从74 mN/m降低至36.4～39.4 mN/m. 理化性能研究结果表明,TETA-DGEPG-EPON834具有优良的水溶性和良好的表面活性,用它作为相反转乳化剂,可制备出稳定的纳米级CARDURA E-10封端的EPON828-TETA加成物水性环氧固化剂胺基分散体乳液.     

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。     

聚醚型多嵌段共聚物软链段结晶特性的研究

本文使用虹外光谱及膨胀计等方法,对聚四亚甲基醚二醇类多嵌段共聚物的软链段结晶性进行了研究。在聚醚-聚酯多嵌段共聚物中(PTMEG>60％),其软链段结晶的熔点和结晶速率均随PTMEG含量减少而下降。而在聚醚-聚脲胺酯多嵌段共聚物中,由于N—H和C—O—C之间氢键的作用,即使在低温下,其软链段也难于结晶。此外,高倍拉伸会提高上述二类多嵌段共聚物中软链段结晶的熔点和结晶速率。     

聚乙二醇-聚乳酸-聚甲基丙烯酸羟乙酯两亲性三嵌段聚合物的合成及其自组装研究

具有生物相容性的两亲性嵌段共聚物在水中易形成胶束,在医学诊断、体内药物缓释及药物靶向输送方面具有广阔的应用前景.利用二嵌段聚合物聚乙二醇-聚乳酸(PEG-PLA)引发甲基丙烯酸羟乙酯的原子转移自由基聚合,制备了两亲性三嵌段聚合物聚乙二醇-聚乳酸-聚甲基丙烯酸羟乙酯(PEG-PLA-PHEMA),利用凝胶渗透色谱(GPC),红外光谱(FT-IR),1H NMR表征了其聚合物组成;然后利用透析法制备了不同分子量的聚合物胶束,动态光散射(DLS)和透射电镜(TEM)结果表明其形貌规整、尺寸均一,而且胶束粒径在PEG和PLA链段长度不变的条件下,随PHEMA链段的变长而增大.PHEMA链上大量羟基的存在为聚合物胶束的功能化改性提供了反应位点,加上本身完全由具良好生物相容性的聚合物制备,使其在可控药物释放方面具有很大的应用潜力.     

聚(苯乙烯-ε-己内酯)嵌段共聚物的研究

本文采用活性阴离子聚合方法合成聚(苯乙烯-ε-己内酯)嵌段共聚物。研究了聚合反应条件,并用GPC、柱上溶解分级及红外光谱进行表征。对产物进行结构分析,产物为聚(苯乙烯-ε-己内酯)嵌段共聚物,具有多相结构,是由无定形聚苯乙烯链段、无定形聚-ε-己内酯链段和结晶型聚-ε-己内酯链段组成的嵌段共聚物。对该嵌段共聚物的性能进行了测试。     

EFFECTS OF SOLVENT TREATMENT ON SURFACE MORPHOLOGY AND COMPOSITION OF POLY(METHYL METHACRYLATE)-g-POLY(ETHYLENE OXIDE)

Surface morphology and composition of solution-cast films of poly(methyl methacrylate)-g-poly(ethylene oxide)(PMMA-g-PEO) were investigated by using XPS, DSC, SEM and contact angle measurement. The microphase separatedstructure of the copolymers was studied by TEM. Generally, for the same graft copolymer, the surface content of PEO orhydrophilicity can be as follows: Surface treated with petroleum ether or cyclohexane>surface untreated with solvent>surface treated with water or ethyl alcohol. Graft copolymer having longer PEO side chains and higher PEO content shows aseparated PEO phase with even a certain degree of crystallinity on the surface. PEO crystallinity was destroyed by water orethyl alcohol treatment, however, surface treatment with petroleum ether or cyclohexane favors the growth of PEO crystal.TEM shows that graft copolymers with longer PEO side chains (M_n of PEO, 3200) may readily undergo microphase separation and the shape and size of domains depend on the copolymer's composition.     

Isothermal crystallization kinetics of PEO in poly(ethylene terephthalate)–poly(ethylene oxide) segmented copolymers. I. Effect of the soft‐block length

The isothermal crystallization kinetics of poly(ethylene oxide) (PEO) block in two poly(ethylene terephthalate) (PET)–PEO segmented copolymers was studied with differential scanning calorimetry. The Avrami equation failed to describe the overall crystallization process, but a modified Avrami equation, the Q equation, did. The crystallizability of the PET block and the different lengths of the PEO block exerted strong influences on the crystallization process, the crystallinity, and the final morphology of the PEO block. The mechanism of nucleation and the growth dimension of the PEO block were different because of the crystallizability of the PET block and the compositional heterogeneity. The crystallization of the PEO block was physically constrained by the microstructure of the PET crystalline phase, which resulted in a lower crystallization rate. However, this influence became weak with the increase in the soft‐block length. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3230–3238, 2000     

Hydrophilic–hydrophobic AB diblock copolymers containing poly(trimethylene carbonate) and poly(ethylene oxide) blocks

AB‐type block copolymers with poly(trimethylene carbonate) [poly(TMC); A] and poly(ethylene oxide) [PEO; B; number‐average molecular weight (M_n) = 5000] blocks [poly(TMC)‐b‐PEO] were synthesized via the ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of monohydroxy PEO with stannous octoate as a catalyst. M_n of the resulting copolymers increased with increasing TMC content in the feed at a constant molar ratio of the monomer to the catalyst (monomer/catalyst = 125). The thermal properties of the AB diblock copolymers were investigated with differential scanning calorimetry. The melting temperature of the PEO blocks was lower than that of the homopolymer, and the crystallinity of the PEO block decreased as the length of the poly(TMC) blocks increased. The glass‐transition temperature of the poly(TMC) blocks was dependent on the diblock copolymer composition upon first heating. The static contact angle decreased sharply with increasing PEO content in the diblock copolymers. Compared with poly(TMC), poly(TMC)‐b‐PEO had a higher Young's modulus and lower elongation at break. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4819–4827, 2005     

DETERMINATION OFTHE CRYSTALLINITY IN DIFFERENT TYPE POLY (OXYETHYLENE-STYRENE)BLOCK COPOLYMERS BY X-RAY DIFFRACTION METHOD

By means of the intensity theory of X-ray scattering and the two-phase concept of high polymer, the basic formula of the crystaUinity in block copolymers has been proposed after the corrections of atomic, temperature, absorption, Lorentz and polarization factor. Application of this method to different type poly (oxyethylene-styrene)block copolymers and the same type block copolymers with different EO contents indicates that the crystallinity in poly (oxyethylene-styrene ) block copolymers increases with the increase of the EO content and decreases in the order: PEO-PS-PEO>PEO-PS>PS-PEO-PS.     

Synthesis and Characterization of New Block Copolymers with Poly(ethylene oxide) and Poly[3(S)‐sec‐butylmorpholine‐2,5‐dione] Sequences

Four different types of polydepsipeptide‐polyether block copolymers were synthesized via ring‐opening polymerization of 3(S)‐sec‐butylmorpholine‐2,5‐dione (BMD) in the presence of hydroxytelechelic poly(ethylene oxide) (PEO) with stannous octoate as a catalyst.The polymers were an AB block copolymer, an ABA block copolymer, an (A)₂B star shaped copolymer and an (A)₂B(A)₂ copolymer, where A is a poly[3(S)‐sec‐butylmorpholine‐2,5‐dione] (PBMD) and B a poly(ethylene oxide) block. The molar ratio of BMD to PEO was varied to obtain copolymers with different weight fractions of PBMD blocks ranging from 59.8 to 96.7 wt.‐%. The crystallinity of the PEO phase in the copolymers decreases in the following order: AB > (A)₂B > ABA > (A)₂B(A)₂ . The static contact angle θ decreases with increasing PEO content in the block copolymers.     

Poly(ethylene imine)‐graft‐poly(ethylene oxide) brush‐like copolymers: Preparation,thermal properties,and selective supramolecular inclusion complexation with α‐cyclodextrin

Poly(ethylene imine)‐graft‐poly(ethylene oxide) (PEI‐g‐PEO) copolymers were synthesized via Michael addition reaction between acryl‐terminated poly(ethylene oxide) methyl ether (PEO) and poly(ethylene imine) (PEI). The brush‐like copolymers were characterized by means of Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. It is found that the crystallinity of the PEO side chains in the copolymers remained unaffected by the PEI backbone whereas the crystal structure of PEO side chains was altered to some extent by the PEI backbone. The crystallization behavior of PEO blocks in the copolymers suggests that the bush‐shaped copolymers are microphase‐separated in the molten state. The PEO side chains of the copolymers were selectively complexed with α‐cyclodextrin (α‐CD) to afford hydrophobic side chains (i.e., PEO/α‐CD inclusion complexes). The X‐ray diffraction (XRD) shows that the inclusion complexes (ICs) of the PEO side chains displayed a channel‐type crystalline structure. It is identified that the stoichiometry of the inclusion complexation of the PEI‐g‐PEO with α‐CD is close to that of the control PEO with α‐CD. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2296–2306, 2008     

Hydrophilic segmented block copolymers based on poly(ethylene oxide) and monodisperse amide segments

Segmented block copolymers based on poly(ethylene oxide) (PEO) flexible segments and monodisperse crystallizable bisester tetra‐amide segments were made via a polycondensation reaction. The molecular weight of the PEO segments varied from 600 to 4600 g/mol and a bisester tetra‐amide segment (T6T6T) based on dimethyl terephthalate (T) and hexamethylenediamine (6) was used. The resulting copolymers were melt‐processable and transparent. The crystallinity of the copolymers was investigated by differential scanning calorimetry (DSC) and Fourier Transform infrared (FTIR). The thermal properties were studied by DSC, temperature modulated synchrotron small angle X‐ray scattering (SAXS), and dynamic mechanical analysis (DMA). The elastic properties were evaluated by compression set (CS) test. The crystallinity of the T6T6T segments in the copolymers was high (>84%) and the crystallization fast due to the use of monodisperse tetra‐amide segments. DMA experiments showed that the materials had a low T_g, a broad and almost temperature independent rubbery plateau and a sharp flow temperature. With increasing PEO length both the PEO melting temperature and the PEO crystallinity increased. When the PEO segment length was longer than 2000 g/mol the PEO melting temperature was above room temperature and this resulted in a higher modulus and in higher compression set values at room temperature. The properties of PEO‐T6T6T copolymers were compared with similar poly(propylene oxide) and poly(tetramethylene oxide) copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4522–4535, 2007     

NUCLEATION MECHANISM OF PEO BLOCK IN DOUBLE-CRYSTALLINE POLY（ETHYLENE-co-BUTENE）-b-POLY（ETHYLENE OXIDE） BLOCK COPOLYMERS

In this paper, we proposed a method to determine the nucleation effect of pre-existing crystals on crystallization of the second block in double crystalline block copolymers, which is usually covered by the suppression effect. The nucleation mechanism of poly（ethylene oxide） （PEO） block from the pre-crystallized polyethylene （PE） block in poly（ethylene-cobutene）-b-poly（ethylene glycol） （EmEOn） diblock copolymers was investigated under variable crystallization environments. The crystallization environment for the PEO block was altered by cooling at different cooling rates or successive selfnucleation （SSN） to the PE block. It was found that the presence of nucleation effect is strongly dependent on composition of the block copolymers. The crystallization temperature （Tc） of PEO block in E174EO90 increases as cooling rate applied to the PE block decreases, indicating that PE block can nucleate the crystallization of PEO block and more perfect PE crystals have stronger nucleation effect. In E182EO41 crystallization of the PEO block is confined, shown by the disappearance of selfnucleation domain, and the PE block has no nucleation effect on the crystallization of PEO block. Double crystallization peaks are observed for the PEO block in E182EO41 and the intensity of the crystallization peak at higher temperature increases as the PE crystals become more perfect. After exclusion of homogeneous nucleation mechanism, the higher temperature crystallization peak of the PEO block in E182EO41 is tentatively ascribed to surface nucleation.     

苯乙烯-氧乙烯-苯乙烯三嵌段聚合物的受限结晶行为的反气相分析

 采用反气相法研究了苯乙烯 氧乙烯 苯乙烯三嵌段结晶聚合物 (PS PEO PS)的结晶熔融相变 ,测定了PS PEO PS的结晶度、熔点以及熔程 ,探讨了正构烷烃探针分子的碳链长度对测定结果的影响。研究结果表明 :PS PEO PS的微相分离对PEO链段的结晶行为有较大的影响 ,其晶体结构中存在由多种不完善PEO结晶和PS非结晶构成的中间层 ;正构烷烃探针分子的碳链长度对测定PS PEO PS的熔点和熔程无影响 ,但对结晶度测定和PEO结晶熔融相变的检测影响较大 ,所测得PS PEO PS的结晶度随正构烷烃探针分子碳链的增长而降低。     

Micellization phenomena of biodegradable amphiphilic triblock copolymers consisting of poly(beta-hydroxyalkanoic acid) and poly(ethylene oxide)

This paper reports the studies on micelle formation of new biodegradable amphiphilic poly(ethylene oxide)-poly[(R)-3-hydroxybutyrate]-poly(ethylene oxide) (PEO-PHB-PEO) triblock copolymer with various PHB and PEO block lengths in aqueous solution. Transmission electron microscopy showed that the micelles took an approximately spherical shape with the surrounding diffuse outer shell formed by hydrophilic PEO blocks. The size distribution of the micelles formed by one triblock copolymer was demonstrated by dynamic light scattering technique. The critical micellization phenomena of the copolymers were extensively studied using the pyrene fluorescence dye absorption technique, and the (0,0) band changes of pyrene excitation spectra were used as a probe for the studies. For the copolymers studied in this report, the critical micelle concentrations ranged from 1.3 x 10(-5) to 1.1 x 10(-3) g/mL. For the same PEO block length of 5000, the critical micelle concentrations decreased with an increase in PHB block length, and the change was more significant in the short PHB range. It was found that the micelle formation of the biodegradable amphiphilic triblock copolymers consisting of poly(beta-hydroxyalkanoic acid) and PEO was relatively temperature-insensitive, which is quite different from their counterparts consisting of poly(alpha-hydroxyalkanoic acid) and PEO.