在含嵌段共聚物的“稳固体溶液”中决定共聚物胶束作用的诸因素

 在含嵌段共聚物可结晶型“稀固体溶液”的结晶过程中,我们已发现共聚物胶束既可起着成核剂的作用,也可起抑制成核数目的作用.本文根据进一步的研究结果,论述了共聚物胶束是起着成核剂的作用,还是起抑制成核作用或对体系的成核行为无影响主要取决于共聚物和均聚物的相对结晶能力及共混体系的相容性.     

嵌段共聚物/均聚物共混体系的结晶行为 I. 非球状共聚物胶束的作用

将Leibler, Whitmore和Mayes等近期关于非晶嵌段共聚物“稀固体溶液”的理论应用于嵌段聚共聚物结晶型“稀固体溶液”结晶行为的研究。发现球状共聚物胶束既可起成核剂作用, 也可起抑制成核作用。报导了当共聚物胶束由球形变为非球形时, 共聚物胶束的上述作用都会发生较大的变化, 并根据Leibler和Mayes分别提出的球形和非球形胶束理论解释了这一实验现象。     

嵌段共聚物/均聚物共混体系的结晶行为——Ⅰ.非球状共聚物胶束的作用

将Leibler,Whitmore和Mayes等近期关于非晶嵌段共聚物“稀固体溶液”的理论应用于嵌段聚共聚物结晶型“稀固体溶液”结晶行为的研究。发现球状共聚物胶束既可起成核剂作用,也可起抑制成核作用。报导了当共聚物胶束由球形变为非球形时,共聚物胶束的上述作用都会发生较大的变化,并根据Leibler和Mayes分别提出的球形和非球形胶束理论解释了这一实验现象。     

微量PEO-PS-PEO/PEO共混体系结晶过程中共聚物胶束的成核作用

本工作将Leibler等近期关于含非晶两嵌段共聚物“稀固体溶液”的胶束理论推广并应用到含结晶三嵌段共聚物的“稀固体溶液”.对微量聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物/聚氧化乙烯均聚物共混体系的结晶行为进行了研究.结果表明,共聚物胶束在共混体系的结晶过程中可以起到成核剂的作用.这对改善结晶均聚物的性能具有一定的应用价值.     

微量PEO-PS-PEO/PEO共混体系结晶过程中共聚物胶束的成核作用

 本工作将Leibler等近期关于含非晶两嵌段共聚物“稀固体溶液”的胶束理论推广并应用到含结晶三嵌段共聚物的“稀固体溶液”.对微量聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物/聚氧化乙烯均聚物共混体系的结晶行为进行了研究.结果表明,共聚物胶束在共混体系的结晶过程中可以起到成核剂的作用.这对改善结晶均聚物的性能具有一定的应用价值.     

微量聚四氢呋喃-聚甲基丙烯酸甲酯/聚四氢呋喃共混体系稀固体溶液中共聚物胶束的抑制成核作用

本工作将Leibler、Whitmore和Mayes等近期关于非晶嵌段共聚物共混体系胶束理论应用于结晶嵌段共聚物共混体系的熔融态,对聚甲基丙烯酸甲酯-聚四氢呋喃两嵌段共聚物与聚四氢呋喃均聚物共混体系的结晶行为进行了研究.结果表明,很低的共聚物浓度(如1％),其胶束在共混体系的结晶过程中即可显著地起到抑制成核的作用.这对改善结晶均聚物的形态及性能有一定的应用价值.     

微量聚四氢呋喃-聚甲基丙烯酸甲酯/聚四氢呋喃共混体系稀固体溶液中共聚物胶束的抑制成核作用

 本工作将Leibler、Whitmore和Mayes等近期关于非晶嵌段共聚物共混体系胶束理论应用于结晶嵌段共聚物共混体系的熔融态,对聚甲基丙烯酸甲酯-聚四氢呋喃两嵌段共聚物与聚四氢呋喃均聚物共混体系的结晶行为进行了研究.结果表明,很低的共聚物浓度(如1％),其胶束在共混体系的结晶过程中即可显著地起到抑制成核的作用.这对改善结晶均聚物的形态及性能有一定的应用价值.     

成核剂对聚丙烯及其共聚物的结晶行为和性能的影响

研究了成核剂1,3:2,4-对二乙基苄叉山梨醇(EDBS)对聚丙烯及其乙烯共聚物的结晶行为和结晶形态的影响,并对其薄膜进行了光学性能的表征.结果表明,添加少量(质量分数0.5%)的成核剂,使聚丙烯样品的结晶温度大大提高,结晶度明显增加.而对于乙烯共聚聚丙烯样品,添加少量(质量分数0.5%)成核剂,不仅使其整体结晶温度大大提高,结晶度增加,而且明显强化了低有序部分的结晶.少量成核剂的加入,使聚丙烯及其共聚物的球晶尺寸明显缩小,薄膜的透光性和雾度显著改善.     

低乙烯含量聚丙烯共聚物结晶成核剂研究

利用ＤＳＣ和偏光显微镜等手段研究了部分成核剂对聚丙烯均聚物（ＰＰ）、低乙烯含量聚丙烯共聚物及聚丙烯／聚乙烯（ＰＰ／ＰＥ）共混物结晶行为的影响，结果表明所用成核剂对ＰＰ和改性ＰＰ具有一定的普适性。聚丙烯共聚物中，由于链结构规整性变差，成核剂的作用显得特别突出，而ＰＰ／ＰＥ共混物中，由于成核剂向ＰＥ相迁移而使其对ＰＰ结晶的成核效率降低。     

水溶性聚合物和两亲聚合物 21.丙烯酸/乙酸乙烯酯共聚物对碳酸钙结晶的影响

研究了晶种存在下丙烯酸／乙酸乙烯酯无规共聚物对碳酸钙从过饱和水溶液中结晶的影响。发现我们的实验条件下碳酸钙结晶包括溶液本体成核结晶和晶种上晶体生长两种不同过程，丙烯酸／乙酸乙烯酯共聚物同时具有明显抑制溶液成核结晶和抑制晶种上晶体生长的双重作用，而且这两种抑制碳酸钙结晶的作用均随共聚物中乙酸乙烯酯含量的增加而加强。     

Crystallization of micelles and matrix in dilute diblock copolymer/homopolymer solutions

The crystallization, morphology, and crystalline structure of dilute solid solutions of tetrahydrofuran–methyl methacrylate diblock copolymer (PTHF-b-PMMA) in poly(ethylene oxide) (PEO) and PTHF have been studied with differential scanning calorimetry (DSC), X-ray, and optical microscopy. This study provides a new insight into the crystallization behavior of block copolymers. For the dilute PTHF-b-PMMA/PEO system containing only 2 to 7 wt % of PTHF content, crystallization of the PTHF micellar core was detected both on cooling and on heating. Compared the crystallization of the PTHF in the dilute solutions with that in the pure copolymer, it was found that the crystallizability of the PTHF micellar core in the solution is much greater than that of the dispersed PTHF microdomain in the pure copolymer. The stronger crystallizability in the solution was presumably due to a softened PMMA corona formed in the solution of the copolymer with PEO. However, the “soft” micelles formed in the solution (meaning that the glass transition temperatures (T_g) of the micelle is lower than the T_m of the matrix phase) showed almost no effects on the spherulitic morphology of the PEO component, compared with that of the pure PEO sample. In contrast, significant effects of the micelles with a “hard” PMMA core (meaning that the T_g of the core is higher than the T_m of the PTHF homopolymer) on the nucleation, crystalline structure, and spherulitic morphology were observed for the dilute PTHF-b-PMMA/PTHF system. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2961–2970, 1998     

Rheological Properties of Silica Suspensions in Aqueous Solutions of Block Copolymers and Their Water-Soluble Components

Dynamic moduli of fumed silica suspensions in aqueous solutions of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers and PEO homopolymers were measured as a function of surface coverage. Since the block copolymers and PEO are adsorbed on the silica surface through hydrogen bonding between the ether oxygen and the silanol group on the silica surface, the interaction between the silanol groups, which is dominant for the aggregation of silica particles, should be prohibited. Dynamic moduli in the silica suspensions were strongly related to the stability of the silica suspensions and the block copolymer, and the longest PEO portion was useful for stabilizing the silica particles. However, the PEO homopolymer did not support stability of the silica particles, suggesting that chain conformation of the PEO portion in the block copolymer is different from that for the PEO homopolymer. Copyright 2001 Academic Press.     

Complexation of linear and poly(ethylene oxide)‐grafted poly(methacryl oxyethyl trimethylammonium chloride) with poly(ethylene oxide‐block‐sodium methacrylate)

The interactions between oppositely charged polyelectrolytes were studied in saline aqueous solutions as functions of the temperature and the salt and polymer concentrations. The polyanion was a diblock copolymer composed of a poly(ethylene oxide) block and a poly(sodium methacrylate) block. Two polycations were used, the homopolymer poly(methacryl oxyethyl trimethylammonium chloride) and its poly(ethylene oxide)‐grafted analogue. By dynamic light scattering and turbidity measurements, it was observed that the salt concentration, temperature, and counterion size had a significant effect on the formation of the polymer complexes in aqueous solutions. At a fixed salt concentration and a fixed temperature, it was possible to form completely soluble complexes of an ionic polymer in aqueous solutions between poly(ethylene oxide)‐grafted poly(methacryl oxyethyl trimethylammonium chloride)and the polyanion with a poly(ethylene oxide) block at a 1:1 anion/cation ratio. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1904–1914, 2003     

聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物/聚苯醚共混物的相容性和结晶行为

本工作对聚氧化乙烯-聚苯乙烯-聚氧化乙烯(PEO-PS-PEO)三嵌段共聚物与聚苯醚(PPO)均聚物共混物的相容性及结晶行为进行了研究。结果表明,共混体系的相容性与嵌段共聚物中苯乙烯段的含量有关,PS含量越高,PPO与共聚物PS段的相容性越好。共混体系的结晶行为也明显不同于一般均聚物共混体系。在DSC降温结晶过程中最多可出现三个结晶峰。