主链型液晶聚硅氧烷聚氨酯的合成及性质

合成了主链型联苯类及氧化偶氯苯类液晶聚硅氧烷聚氨酯弹性体，采用红外光谱，示差扫描量热，动态粘弹谱及带热台偏光显微镜等方法对聚合物进行了表征，讨论了它们的结构与性能．研究结果表明，这一系列多嵌段聚氨酯多数是向列型的液晶高分子聚合物，液晶相的形成同嵌段聚氨酯样品的软硬段相互作用有着密切的联系     

含液晶二醇聚氨酯研究

合成了具有液晶性质的二元醇一对苯二甲酰二羟苯甲酸丁二醇酯（ＴＯＢＢ），这种二元醇单独或与端羟基聚了二烯（ＨＴＰＢ）混合后与二异氰酸酯反应生成几种聚氨酯，用ＩＲ，ＤＳＣ，偏光显微镜和ＷＡＸＤ对它们进行了表征，证明这种二元醇和聚氨酯都具有液晶性质。     

固体变温核磁共振碳谱研究主链型热致液晶聚醚聚氨酯弹性体

固体变温核磁共振碳谱研究主链型热致液晶聚醚聚氨酯弹性体陈群，杨光，王源身（华东师范大学分析测试中心上海２０００６２）余学海（南京大学高分子系南京２１０００８）黑子弘道，安藤勋（日本东京工业大学高分子工学科）关键词主链型热致液晶聚氨酯弹性体，固体变温高...     

偶氮液晶基元封端聚氨酯的合成与性能研究

以丁二酸酐、苯胺和对硝基苯胺为原料,经两步反应制得一种偶氮液晶基元(2);2与不同分子量的聚氨酯预聚体通过封端反应合成了一系列偶氮液晶聚氨酯(4a～4e),其结构和液晶性能经UV,NMR,FT-IR,TGA,DSC,POM和XRD等表征.结果表明,2从室温到熔点温度均表现出液晶态的强双折射.4a～4e为热致/溶致型液晶聚氨酯,具有较宽的液晶相温度区间.4的DMF溶液的临界浓度[w(4)]为3%～6%.     

有机硅改性席夫碱聚氨酯型液晶固定相的制备、表征及色谱性能

以对苯二胺、3-氯丙醇和4-羟基苯甲醛为原料,合成对苯二(对苯丙氧基醇)亚胺液晶基元,再与对苯二异氰酸酯和1,3-双(3-氨基丙基)四甲基二硅氧烷反应,合成席夫碱型硅氧烷聚氨酯液晶聚合物。 通过红外光谱法、X射线衍射、热分析、偏光显微镜等技术手段对其结构和性能进行了表征。 结果表明,该物质为席夫碱有机硅聚氨酯液晶聚合物,属于近晶相液晶,液晶区间为103~150 ℃,热分解温度为300 ℃。 用席夫碱型硅氧烷聚氨酯液晶固定相制备填充色谱柱,考察固定液的相对极性及其对取代苯位置异构体的色谱分离性能。 合成的席夫碱型硅氧烷聚氨酯液晶聚合物的液晶温度范围为103~146 ℃,属于强极性固定液(P_x=79),各组分色谱峰的分离度为0.96~3.33。     

芳香族偶氮苯封端的液晶聚氨酯膜的制备及其液晶性能

以苯胺或对硝基苯胺为主要原料,经重氮偶合反应制得液晶基元对氨基偶氮苯(LC1)或对硝基偶氮苯胺( LC2),再用聚氨酯预聚体[由聚乙二醇(PEG400,含-OH)和二苯基甲烷二异氰酸酯(MDI,含-NCO)制得,r=n(-OH)∶n(-NCO)]封端合成了一系列偶氮液晶聚氨酯膜LCPU'1和LCPU'2,其结构和液晶性能经UV,IR,TGA,POM与XRD表征.结果表明,LCPU'1和LCPU'2为具有良好热稳定性的热致型向列型液晶聚氨酯.LCPU3/41的接触角较大,耐水性相对较佳,硬度也相对适中.     

手性丙烯酸酯侧链液晶聚合物液晶行为的聚合物效应

研究了手性丙烯酸酯侧链液晶聚合物聚４ 丙烯酰十一烷氧基 ４′ ［Ｓ（ ） ２ 甲基丁氧基］ 联苯（ＰＡ １１）的分子量对其液晶行为的影响，结果表明，ＰＡ １１的相变温度随聚合度增大而升高，当聚合度大于１５以后，分子量对相变温度影响不明显，低聚合度的ＰＡ １１只表现出双向性的ＳＡ相，而聚合度大于７的ＰＡ １１不仅具有双向性ＳＡ相，而且还表现出双向性ＳＣ相；分子量分布对ＰＡ １１的液晶相转变也有影响     

新型侧链液晶聚氨酯扩链剂的合成与表征

本文合成了用以制备侧链型液晶聚氨酯的扩链剂二醇－４（４－甲氧基苯酰氧基）苯甲酸－双（β－羟乙基）氨基乙酯（ＩＶ），并以ＨＮＭＲ。ＦＴＩＲ、元素分析等测试手段对此二醇进行了表征，测试结果与设定结构相一致     

甲壳型液晶高分子的化学结构及其与性能间关系的研究

设计并合成了7种新型甲壳型液晶高分子,研究了液晶基元的化学结构和立体效应对单体及其聚合物液晶性的影响.发现在液晶基元的末端引入极性或可极化的原子基团提高了单体的熔点和液晶相的热稳定性;液晶基元的长径比越大,单体的熔点和清亮点越高;聚合使单体的液晶稳定性增加、液晶相温度范围变宽;侧链液晶基元的极性、刚性和空阻越大,聚合物的玻璃化温度越高;酰胺基团无论是在分子的末端还是在连接部位,都使单体的熔点和聚合物的玻璃化温度提高,但在分子末端时液晶相较稳定,作为中心桥键时不利于液晶相的稳定形成.     

液晶聚酯与环氧嵌段共聚物的合成及表征

近年来 ,人们利用高分子液晶作为热固性环氧树脂的改性剂 ,不仅可以提高环氧树脂的韧性和强度 ,而且可以改善其热性能 ,为制备高性能的环氧树脂提供了一条新的途径[1,2 ] .目前报道所使用的液晶聚合物大多为液晶聚酯[3 ] 或液晶性聚氨酯[4] ,这些液晶聚合物与环氧树脂由于存在相容性不好的问题 ,给其实际应用带来了困难 .为了改善二者的相容性 ,本文采用溶液法合成了末端带有反应活性基团的聚酯型液晶聚合物 ,将它再与双酚Ａ环氧预聚物反应 ,制得了高分子液晶环氧嵌段共聚物 ,其合成路线如下 :2ＨＯＣＯＯＣＨ3+ ＨＯ(ＣＨ2 ) 6 ＯＨ　　Ｈ…     

Marangoni stresses and surface compression rheology of surfactant solutions. Achievements and problems

In the presence of soluble surfactants, the motion of liquid surfaces involves Marangoni effects. As a consequence, the surfaces exhibit elastic responses, even frequently behaving as rigid surfaces, especially at low surfactant concentration. The Marangoni effects can be conveniently quantified introducing surface viscoelastic compression parameters that characterize the mechanical response of the surface near equilibrium. Many experimental techniques allow measuring the viscoelastic parameters. However, many difficulties are encountered during the interpretation of the surface response in the various types of hydrodynamic velocity fields involved in the different techniques. The role of adsorption and desorption energy barriers appears crucial, despite the fact that little is known yet about their values. In this short review, we will present examples illustrating the different problems.     

Studies on Liquid Crystalline Bis[4-(p-phenoxy)-phenylbenzoate]-Alkyldicarboxylate

ＳｔｕｄｉｅｓｏｎＬｉｑｕｉｄＣｒｙｓｔａｌｉｎｅＢｉｓ［４┐（ｐ┐ｐｈｅｎｏｘｙ）┐ｐｈｅｎｙｌｂｅｎｚｏａｔｅ］Ａｌｋｙｌｄｉｃａｒｂｏｘｙｌａｔｅ＊ＸＩＮＧＰｅｉ－ｘｉａｎｇ,ＴＩＡＮＹａｎ－ｑｉｎｇ,ＷＡＮＧＪｕｎ－ｚｕｏＮＡＨｕｉ,Ｔ...     

Study of the electrocaloric effect in ferroelectric liquid crystals

ABSTRACT

Electrocaloric effect (ECE) in two ferroelectric liquid crystalline (FLC) materials has been evaluated by mean of two indirect characterization methods: the photopyroelectric (PPE) technique and the polarization current reversal one. The obtained results show a good correspondence of the adiabatic temperature change associated with the ECE evaluated from both methods. This validates the possibility to use the PPE technique to investigate the ECE in FLCs. This study also demonstrates that FLCs can be used as electrocaloric material. More particularly, it shows that as for their solid homologous, liquid crystals displays more pronounced ECE in the vicinity of a first order transition than that measured near to second-order one.     

H-shaped liquid crystals inducing nematic order in the isotropic liquid

ABSTRACT

We prepared a homologous series of H-shaped liquid crystals I-n and investigated their phase transition properties using optical microscopy and differential scanning calorimetry. All the compounds exhibited a nematic phase at room temperature. The phase transition behaviour is explained in terms of molecular shape anisotropy. Furthermore, those compounds were found to exhibit electro-optical switching in the isotropic liquid in the vicinity of the nematic–isotropic liquid transition, indicating that the microscopic nematic order with a certain coherence length of the molecules exists in the optically isotropic temperature range.     

The correlation between molecular polarizability of PAHs and their retention data on various stationary phases in reversed-phase HPLC

Summary The equation for the potential energy of interactions established for gas-liquid chromatography has been confirmed in reversed phase liquid chromatography. Equations derived for molecular polarizabilities of PAHs and their retention data have very high correlation coefficients. The results indicate that the inductive effect between solute and stationary phase is the main one and the dispersive effect is very small compared with the inductive effect but its contribution increases with the carbon chain length of the stationary phase.     

Evaluation of the cytotoxicity on breast cancer cell of extracts and compounds isolated from Hyptis pectinata (L.) poit

Abstract

Hyptis pectinata is a herb popularly used in Brazil for the treatment of inflammations, pain, bacterial infections and cancer. In the present study, inflorescences (MPIn), leaves (MPL), branches (MPB), root (MPR) extracts and three compounds isolated from MPIn were assayed against breast tumor cell lines. The structures of the three compounds (pectinolide J, hyptolide and pectinolide E) were determined by means of spectroscopic analysis. Pectinolide J was isolated for the first time. The MPIn, MPL and MPR exhibited specific antiproliferative activity on tumor cell lines when compared to normal cell lines with IC₅₀ of 52.01?±?0.64, 45.91?±?0.02?μg/mL and 82.84?±?0.03?μg/mL, respectively. Although the isolated substances did not present good antiproliferative activity, when the three were associated, a greater biological effect was observed, suggesting a synergistic effect. Hyptolide (5.6?±?0.4?μg/mL) showed IC₅₀ sufficiently low to be considered as a drug prototype.     

Thermotropic polyesters. 1: Synthesis, characterization and thermal transition of poly[4,4-bis(ω-alkoxy)biphenyl isophthalate]

A new homologous series of thermotropic polyesters has been synthesized by polycondensation reaction between isophthaloyl chloride and mesogenic diols 4,4^′-bis(ω-hydroxyalkoxy)biphenyl in which the spacer length is varied from 3 to 6 methylene units. The thermal behavior of the polymers has been characterized using polarized light microscopy and differential scanning calorimetry (DSC). The odd members exhibit a smectic C (S_C) phase in a narrow temperature interval, while the even members form a smectic A (S_A) phase in a broader temperature range. All of the obtained compounds were characterized by conventional spectroscopic methods.