PET-HBT热致液晶嵌段共聚酯的合成及表征

首先以对苯二甲酸双争羟乙酯与过量的对苯二甲酰氧合成了酰氯基封端的ET齐聚物，并以过量的双对羟基苯甲酸丁二醇酯与对苯二甲酰氯合成了酚羟基封端的齐聚物HBT。而后，以四氧乙烷为溶剂，采用溶液缩聚法以ET和HBT为原料，合成嵌段共聚酯(PET—HBT)。用偏光显微镜、^1H—NMR、WAXD及FT—IR表征了嵌段共聚酯的微观结构及结晶行为。在一定的温度范围内，该共聚酯是热致液晶高聚物。     

聚砜—热致液晶嵌段共聚物的合成

针对聚砜—热致液晶聚合物 (PSF TLCP)共混体系相容性差的问题 ,在合成不同分子量羟基封端聚砜 (PSF -OH)低聚体的基础上 ,通过溶液缩聚反应 ,合成了以下 3类嵌段共聚物增容剂 :聚砜—对羟基苯甲酸 (PSF—PHB) ,聚砜—对苯二甲酸乙二醇酯 (PSF -PET)和聚砜—对苯二甲酸对苯二酚酯 (PSF—PHQT)。红外光谱和流变性分析表明 ,合成了具有预期结构的嵌段共聚物 ,并且所合成的嵌段共聚物包含了较长的聚酯链段。     

含HTH—6和PSF的热致液晶嵌段共聚物的合成与表征

以端酰氯基团的热致液晶共聚酯ＨＴＨ－６和端酚羟基的聚砜齐聚物为原料，通过溶液缩聚法制备含ＰＳＦ和ＨＴＨ－６的嵌段共聚物，并用ＩＲ，ＰＯＭ，ＤＳＣ和ＷＡＸＤ等手段对共聚物结构，热行为和结晶行为进行了表征。结果证明，这些嵌段共聚物皆属向列型热致性液晶，在低温下无宏观相分离，而在２８０℃以上的为两相结构。共聚物的结晶结构与ＨＴＨ－６相同，结晶度随ＨＴＨ－６含量增加而增加。     

不饱和聚酯-环氧树脂嵌段共缩聚型光敏预聚物的合成

提出了一种由不饱和聚酯和环氧树脂嵌段共缩聚，合成一类新型先教预聚物的方法。谈光敏预聚物采用两步法合成。第一步先合成具有一定分子量和端羧基的不饱和聚酯，第二步使该不饱和聚酯与环氧树脂反应，生成嵌段共缩聚物。该光敏预聚物的分子量通过调节不饱和聚酯的分子量控制。不同分子量的先教预聚物呈现出不同的光敏性和力学性能。     

二元酚及丁二醇对苯二甲酸共聚酯的液晶性及其取向形态的研究

用酯交换法在聚对苯二甲酸乙二醇酯中引入(?)介晶单元可制得性能优异的热致性共聚酯液晶材料。但对结构相近的聚对苯二甲酸丁二醇酯(PBT)进行类似尝试时,却由于羟基苯甲酸的均聚而遇到困难~([1])。本文合成了以 PBT 为间隔段的热致性液晶共聚酯,并对其取向薄膜形态进行了研究。按下式合成一系列共聚酯:     

BHET-PHB热致液晶聚合物的合成及表征

本实验第一次以时苯二甲酸乙二醇酯(BHET)和对羟基苯甲酸(PHB)为原料，采用熔融缩聚的方法合成了BHET-PHB热致液晶共聚酯。通过红外和核磁验证了合成共聚酯的化学结构，并用DSC、偏先显微镜和X射线衍射研究了其液晶行为，证明合成的BHET-PHB共聚酯为典型的向列型液晶。     

间苯二甲酸对嵌段共聚酯结构和性能的影响

本文通过Ｘ光衍射，ＤＳＣ，ＳＡＸＳ等方法，考察了间苯二甲酸的含量对聚对苯二甲酸乙二醇－聚己二酸乙二醇多嵌段共聚酯结构和性能的影响，发现合成时间苯二甲酸的加入，使共聚酯的Ｗａ，ｘ，Ｔｍ，Ｌｎｋｌ均下降，同时，力学性能也下降，但间苯二甲酸含量为１０％的共聚酯的力学性能最佳。     

热致液晶共聚酯原位复合材料相容性的研究

通过加入液晶聚酯酰胺和聚碳酸酯的多嵌段共聚物, 可以有效地降低基体聚碳酸酯的玻 璃化转变温度, 提高热致液晶高分子PET/60PHB 与聚碳酸酯原位复合材料的相容性。随嵌段共 聚物含量的增加, 共混物拉伸强度有所提高, 拉伸模量提高了15% , 同时, 冲击强度也得到了增长。 通过扫描电镜(SEM ) 的观察发现, 嵌段共聚物的加入改进了共混体系中两相间界面粘合, 促进了 液晶高分子分散相的变形。      

PEG-IPDI-DMPA嵌段离聚体的合成与表征及其在水相中的溶液行为

采用溶液聚合法合成了PEG-IPDI-DMPA嵌段离聚体,通过FTIR、1H-NMR、GPC、DSC、TEM对其结构进行了表征;并通过粒径、比浓粘度、旋转粘度和电导率,对其在水相中的溶液行为进行了研究。红外光谱分析证实,合成获得了预期的聚氨酯结构嵌段离聚体;差示扫描量热分析证明,离聚体分子链段是由硬段和软段两相组成的嵌段共聚物;经透射电镜观察,嵌段离聚体在水溶液中呈现出较为规整的球形粒子状态。PEG-IPDI-DMPA嵌段离聚体粒径都在200nm左右;PEG-IPDI-DMPA嵌段离聚体是剪切变稀的。     

热致液晶芳香族共聚酯的合成与表征

本文就热致液晶芳香族共聚酯的合成与表征进行了较详细的综述，以期能促进我国液晶高分子材料的开发与应用。     

Characteristics of di- and tri-block copolymers: polymer disperse liquid crystal display

In the reported work the block copolymers are used in the polymer disperse liquid crystal (PDLC) films. The present work has been performed to investigate the effect of block copolymer addition and block ratios on the PDLC characteristics. From our experimental finding, addition of block copolymer in PDLC shows variation in droplet size, electro-optical properties, extent of phase separation, and phase transition temperature. These finding indicate the alteration in solubility parameters of solutions with the addition of block copolymers. Moreover, the tri-block copolymer shows enlarge droplet size, enhancement in the degree of phase separation, and predict improvement in electro-optical properties, as compared to di-block copolymer. Similarly upon such comparison, the study suggests the tri-block copolymer have a relative lower molecular interaction with the liquid crystal molecules.     

聚乳酸嵌段共聚物的制备及扩链研究

为了获得性能更优良的聚乳酸材料,以乳酸、ε-己内酯、丁二酸酐为原料,采用梯度升温法合成了聚乳酸嵌段共聚物,用IPDI对其扩链.采用乌氏黏度法、FT-IR、1H-NMR、TGA及XRD等手段对产物进行了表征.FT-IR和1H-NMR测试结果显示,预期的聚乳酸嵌段共聚物成功合成;几种聚合方法中,以先合成端羟基活性低聚物P(...     

Hierarchical assembly of nanostructured organosilicate networks via stereocomplexation of block copolymers

The effect of the stereochemistry of polylactide (PLA)-based block copolymers on templated inorganic nanostructures has been investigated from the self-assembly of a stereoisomer pair/organosilicate mixture followed by organosilicate vitrification and copolymer thermolysis. Isomeric PLA homopolymers, block copolymers, and a stereoblock copolymer were prepared by ring-opening polymerization of D-, L-, or rac-lactide using an organocatalytic catalyst. Both differential scanning calorimetry and atomic force microscopy showed the formation of a stereocomplex between enantiomeric stereoisomers, that is, block copolymer/block copolymer and block copolymer/homopolymer mixtures as well as a stereoblock copolymer. The unique noncovalent interactions driven by stereocomplexation of D- and L-lactide provided supramolecular structures with a hierarchical order as characterized by distinctive vertical and horizontal growth of toroidal nanostructured inorganic features. This study demonstrates the potential of hierarchically assembling suprastructures that bridge the nano- to mesoscale feature sizes in the design of tunable functional nanomaterials suitable for future applications of microelectronics, material science, and bioengineering.     

Characterization of poly(L-lactide)-block-poly(ethylene oxide)-block-poly(L-lactide) triblock copolymer by liquid chromatography at the critical condition and by MALDI-TOF mass spectrometry

Poly(L-lactide)-block-poly(ethylene oxide)-block-poly(L-lactide) triblock copolymers (PLLA-b-PEO-b-PLLA) were fractionated in terms of the number of LLA units by liquid chromatography at the critical condition (LCCC) of PEO block. The fractionated samples were identified using MALDI-TOF mass spectrometry. The dependence of the LCCC retention of the diblock and triblock copolymers on the degree of polymerization of PLLA block(s) follows Martin's rule very well. Unlike the case of PEO-b-PLLA diblock copolymer reported earlier (Lee, H.; et al. Macromolecules 1999, 32, 4143), however, a splitting of the elution peaks containing the same number of LLA units was found. The peak splitting was ascribed to the different length distributions of PLLA blocks at the two ends of the PEO block. From the relative intensities of the peaks, the split peaks were assigned to different isomeric structures of the PLLA blocks. From these results we conclude that the interaction of the triblock copolymers with the stationary phase is affected by the distribution of the interacting blocks at the two ends of the center PEO block, in addition to the total number of LLA units in the triblock copolymer.     

Ocular permeability of pirenzepine hydrochloride enhanced by methoxy poly(ethylene glycol)-poly(D, L-lactide) block copolymer

Methoxy poly(ethylene glycol)-poly(D,L-lactide) block copolymer was tested as an ocular permeation enhancer for pirenzepine hydrochloride. The block copolymers with the methoxy poly(ethylene glycol) to poly(D,L-lactide) weight ratio of 80/20, 50/50, 40/60 were synthesized by a ring-opening polymerization procedure. In vitro transcorneal experiments demonstrated that the block copolymer 80/20 significantly enhanced the transcorneal permeation of pirenzepine at the mass ratio of 1/1.4 (pirenzepine hydrochloride/copolymer). Interaction between pirenzepine and copolymer was identified by infrared spectroscopy analysis and dialysis experiments. Ocular pharmacokinetics of pirenzepine/copolymer preparation by in vivo instillation experiments confirmed that block copolymer could enhance the ocular penetration of pirenzepine. Ocular chronic toxicity experiments of block copolymer and pirenzepine/copolymer preparation were studied on rabbits, and no significant toxicity in both groups was observed within 9 months. It could conclude that pirenzepine/copolymer preparation is effective and safe in ocular delivery of pirenzepine.     

Ocular Permeability of Pirenzepine Hydrochloride Enhanced by Methoxy poly(ethylene glycol)–poly(D,L-lactide) Block Copolymer

Methoxy poly(ethylene glycol)–poly(D,L-lactide) block copolymer was tested as an ocular permeation enhancer for pirenzepine hydrochloride. The block copolymers with the methoxy poly(ethylene glycol) to poly(D,L-lactide) weight ratio of 80/20, 50/50, 40/60 were synthesized by a ring-opening polymerization procedure. In vitro transcorneal experiments demonstrated that the block copolymer 80/20 significantly enhanced the transcorneal permeation of pirenzepine at the mass ratio of 1/1.4 (pirenzepine hydrochloride/copolymer). Interaction between pirenzepine and copolymer was identified by infrared spectroscopy analysis and dialysis experiments. Ocular pharmacokinetics of pirenzepine/copolymer preparation by in vivo instillation experiments confirmed that block copolymer could enhance the ocular penetration of pirenzepine. Ocular chronic toxicity experiments of block copolymer and pirenzepine/copolymer preparation were studied on rabbits, and no significant toxicity in both groups was observed within 9 months. It could conclude that pirenzepine/copolymer preparation is effective and safe in ocular delivery of pirenzepine.     

Controlling the morphology of side chain liquid crystalline block copolymer thin films through variations in liquid crystalline content

In this paper, we describe methods for manipulating the morphology of side-chain liquid crystalline block copolymers through variations in the liquid crystalline content. By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer (BCP) backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase-segregated BCP microstructures can be precisely manipulated. Increases in LC functionalization lead to stronger preferences for the anchoring of the LC mesophase relative to the substrate and the intermaterial dividing surface. By manipulating the strength of these interactions, the arrangement and ordering of the ultrathin film block copolymer nanostructures can be controlled, yielding a range of morphologies that includes perpendicular and parallel cylinders, as well as both perpendicular and parallel lamellae. Additionally, we demonstrate the utilization of selective etching to create a nanoporous liquid crystalline polymer thin film. The unique control over the orientation and order of the self-assembled morphologies with respect to the substrate will allow for the custom design of thin films for specific nanopatterning applications without manipulation of the surface chemistry or the application of external fields.     

Photopatterning of Cross‐Linkable Epoxide‐Functionalized Block Copolymers and Dual‐Tone Nanostructure Development for Fabrication Across the Nano‐ and Microscales

The self‐assembly of block copolymers in thin films provides an attractive approach to patterning 5–100 nm structures. Cross‐linking and photopatterning of the self‐assembled block copolymer morphologies provide further opportunities to structure such materials for lithographic applications, and to also enhance the thermal, chemical, or mechanical stability of such nanostructures to achieve robust templates for subsequent fabrication processes. Here, model lamellar‐forming diblock copolymers of polystyrene and poly(methyl methacrylate) with an epoxide functionality are synthesized by atom transfer radical polymerization. We demonstrate that self‐assembly and cross‐linking of the reactive block copolymer materials in thin films can be decoupled into distinct, controlled process steps using solvent annealing and thermal treatment/ultraviolet exposure, respectively. Conventional optical lithography approaches can also be applied to the cross‐linkable block copolymer materials in thin films and enable simultaneous structure formation across scales—micrometer scale patterns achieved by photolithography and nanostructures via self‐assembly of the block copolymer. Such materials and processes are thus shown to be capable of self‐assembling distinct block copolymers (e.g., lamellae of significantly different periodicity) in adjacent regions of a continuous thin film.     

聚乙二醇单甲醚/聚己内酯嵌段共聚物的微波合成及胶束制备

微波辅助下聚乙二醇单甲醚(MPEG)引发ε-己内酯(ε-CL)开环聚合合成了聚乙二醇单甲醚/聚己内酯(MPEG-b-PCL)嵌段共聚物,利用核磁共振(1H-NMR)和凝胶渗透色谱(GPC)方法对共聚物结构进行了表征。以芘作荧光探针,研究了共聚物胶束的形成及其临界胶束浓度(CMC)),利用动态光散射(DLS)和透射电镜(TEM)分别研究了胶束的粒径分布和形态。结果表明,在微波辅助下MPEG能够在较短时间内引发ε-CL开环聚合得到嵌段共聚物,当反应时间为5min,微波功率为700 W时能够得到理想的目标共聚物;嵌段共聚物在一定条件下能够形成球形的单分散纳米级胶束,CMC的数量级为10-3mg/mL。     

Diffusion of block copolymers

Block copolymers have been attracting the attention of a great number of scientists and engineers with their beautiful ordered structures on a nanometer scale. Repulsion between dissimilar blocks of block copolymers drives micro-phase separation on the length scale—the radius of gyration of the block copolymer chains. Due to the presence of such nano-domains, the diffusion of block copolymers in the melt is significantly reduced in the direction perpendicular to the interface between the domains. In this direction, block copolymer chains diffuse by an activated hopping mechanism in which the shorter block is pulled out from its domain into the majority domain. Consequently, in this direction the diffusion coefficients of block copolymers decrease exponentially with the activation energy of the hopping process χN_sk_BT, where χ is the Flory parameter, N_s is the degree of polymerization of the shorter block, k_B is Boltzmann's constant and T is temperature. The diffusion along the domain interface is less restricted by the presence of domains. The interface diffusion coefficient depends on the degree of segregation and presence of entanglements. Experiments, theories and simulations of block copolymer diffusion in ordered structures are reviewed.