Effects of annealing on crystallinity and phase behaviour of PET/PC block copolymers

The effects of the annealing on the properties of PET/PC block copolymers, obtained by reactive blending in the presence of different catalysts and for different mixing times, have been studied. The annealing, performed in conditions that promote the crystallization, has been used to better understand the role of block length in determining the phase behaviour. The copolymers characterized by blocks with molecular weight larger than 8000 are able to reorganize towards more ordered domains. This rearrangement maintains the phase separation, as two crystalline phases are present before and after annealing, due to the immiscibility of long blocks. In copolymers characterized by blocks with molecular weight equal to about 2500, that is the higher limit for the miscibility in the amorphous state in PET/PC block copolymers studied in this work, the rearrangement of the chains during annealing causes a phase separation leading to two crystalline phases. Only in the copolymers with molecular weight of blocks lower than 1500, the very short block length hinders the crystallization: therefore, only in this case a phase separation does not take place after annealing.     

Irreversible and reversible phase transitions of alkyl monolayers. Gas chromatographic evidence of polar solvent influence on the adsorbing properties of the layer

Summary Further to Gilpin's observations in liquid chromatography of the irreversible transformation of alkyl grafts, following the replacement of an organic mobile phase by an aqueous one, we describe some gas chromatographic experiments which lead to similar (log V_s, I/T) plots, as a consequence of the same solvent release process.We use paraffin films on siliceous supports or hydroxylated liquid substrates or C₂₂-alkyl bonded silica. These experiments demonstrate that this irreversible transition and the melting-like reversible transition are completely different phenomena. They confirm the existence of at least three kinds of monomeric alkyl films.     

Stationary phase properties of the organic molten salt ethylpyridinium bromide in gas chromatography

Summary The organic molten salt, 1-ethylpyridinium bromide, is suitable for use as a stationary phase in gas chromatography. It has a usable liquid temperature range of 110 to 160°C. It undergoes a single phase transition at 110°C which corresponds to the bulk melting point. Below the melting point the phase may be used as a selective adsorbent, although column efficiency and peak symmetry deteriorate as the temperature is lowered from the melting point. Above the melting point, ethylpyridinium bromide can be used to separate a wide variety of organic compounds retaining strongly those compounds possessing large dipole or hydrogen bonding functional groups.     

Molecular aggregation in the ternary system deca glycerol dioleate/heptane/water

The phase diagram for the ternary system deca glycerol dioleate(DGD)/heptane/water was established at 25 °C. In this phase diagram it was seen that the reverse micellar solution phase extends in its area until the water content reaches 35–45 wt%, at which a liquid crystalline phase begins to appear. On the basis of the experimental results of specific conductivity, viscosity, etc. for the samples containing a definite amount of DGD (0,1 M), and varying relative amounts of heptane and water, the mechanism of the transition of reverse micellar structures to liquid crystalline phase is discussed.     

等规聚苯乙烯的分子量分级

用配位聚合法得到的高等规度的等规聚苯乙烯(i-PS),一般具有较宽的分子量分布,对其进行分子量分级是比较难的,迄今已有不少这方面的报道,其中包括采用热力学的方法,以及采用分子量降解的方法。为了获得分子量分布较窄的i-PS样品来研究单链单晶,我们也进行了i-PS的分级研究,我们选用了一种新的溶剂/不良溶剂体系对i-PS     

含L－氨基酸结构的手性液晶化合物的合成及其相变行为

合成了９种具Ｌ－氨基酸衍生物结构的介晶化合物（Ｉ－Ⅲ，Ⅳａｂ，Ⅴａ，ｂ，Ⅵａ，ｂ）、４种氨基酸衍生物（Ａ１－４）和６种介晶化合物（Ｍ１－６）．新化合物（Ⅰ－Ⅲ，Ⅳａ，ｂ，Ⅴａ，ｂ，Ⅵａ，ｂ，Ａ４，Ｍ３－６）的化学结构通过ＩＲ、１ＨＮＭＲ和元素分析证实；并用偏光显微观察和ＤＳＣ分析研究了其相变行为，结果表明有８种化合物（Ｍ３－６，Ⅵａ，ｂ，Ⅴｂ，Ⅵｂ）呈现液晶相变。测定了它们的比旋光度。通过Ｘ射线衍射研究了化合物Ⅵｈ１２０～１３０℃和Ⅵｂ１７０～１８０℃的近晶结构，Ⅵｂ显，Ⅵｂ呈。测定了化合物Ⅳｂ的电滞回线，证明其具铁电性。     

N－取代硫代磷酰胺二乙酯合成新方法的研究

以ＰＥＧ作相转移催化剂，在无机碱（Ｋ＿２ＣＯ＿３或Ｎａ＿２ＣＯ＿３）存在下，用乙基氯化物（Ｏ，Ｏ－二乙基硫代磷酰氯）与不同的胺反应，合成了六种Ｎ－取代硫代磷酰胺二乙酯，其结构经ＩＲ、ＮＭＲ和元素分析证实。     

1－芳氧基乙酰基－4－邻氯苯甲酰基氨基硫脲衍生物的合成及其生物活性研究

于固－液相转移催化条件下，合成了１０个１－芳氧基乙酰基－４－邻氯苯甲酰基氨基硫脲衍生物，用元素分析、ＩＲ和￣１Ｈ－ＮＭＲ光谱确定了它们的结构。该类化合物对小麦幼苗生长具有明显的促进作用。     

全芳香族共聚酯的结构和其液晶行为研究

本文对不同组成的对苯二甲酸(TPA),对羟基苯甲酸(PHBA),联苯二酚(BP),间苯二甲酸(IPA)共聚酯采用热台偏光显微镜、电子显微镜、X-射线衍射、激光小角散射、差热等技术进行了研究.实验结果表明,在一定的组成范围内共聚酯熔体有很好的液晶性.重点讨论了分子组成、转变行为、液晶性的关系,并对液晶相的形态结构进行了表征.     

低共熔混合锂盐相图的绘制及应用

采用热分析法对不同组成的混合锂盐二元体系进行研究, 绘制了混合锂盐体系的步冷曲线和T-x相图, 结果表明体系均为具有最低共熔点的二元体系. LiOH-LiNO3、LiOH-LiCl、LiOH-Li2CO3及LiNO3-LiCl体系的最低共熔点分别为175.7、294.5、418.2及221.6 ℃. 利用低共熔混合物LiNO3-LiOH为锂盐与不同前驱体反应, 制备出了层状结构良好的锂离子电池正极材料LiNiO2、LiNi0.8Co0.2O2及LiNi1/3Co1/3Mn1/3O2. X射线衍射分析表明, 合成的材料具有规整的层状NaFeO2结构, 且XRD衍射峰强度之比I(003)/I(104)>2.0, 电性能测试表明, 在2.7-4.3 V(vs Li/Li+)的电压范围内进行0.1C倍率充放电, LiNiO2、LiNi0.8Co0.2O2、LiNi1/3Co1/3Mn1/3O2首次充电比容量分别达168.0、225.4、194.0 mAh·g-1, 放电比容量分别为138.4、165.8、157.7 mAh·g-1.