嵌段共聚物PS-b-PMMA在PCHMA/PMMA共混体系中增容效果的研究:嵌段比、分子量及粘度的影响

采用熔融共混方式,利用两嵌段共聚物聚苯乙烯-b-聚甲基丙烯酸甲酯(PS-b-PMMA)来增容聚甲基丙烯酸环己酯(PCHMA)/聚甲基丙烯酸甲酯(PMMA)共混体系,主要研究PS-b-PMMA嵌段比、均聚物的分子量以及体系粘度对增容效果的影响。研究发现,非对称结构的嵌段共聚物较对称结构的嵌段共聚物更容易在体相形成胶束,胶束的形成减少了嵌段共聚物在界面的利用率。均聚物分子量增大,嵌段共聚物的胶束均增加。分散相分子量增大,造成了界面的嵌段共聚物稳定性减弱,容易扩散至分散相内部,形成胶束。连续相分子量增大致使链段溶胀力减小,嵌段共聚物胶束外围的乳化效果降低,而且连续相粘度增大,使得嵌段共聚物胶束滞留在连续相,难以迁移至界面。共混体系的混合剪切增加,粘度变小,嵌段共聚物的扩散速率加快。通过调控均聚物分子量和体系粘度,能有效地减少体相胶束的形成,增大嵌段共聚物在界面的利用率。通过Leibler干湿刷理论、焓驱溶胀聚合物刷以及Stokes-Einstein扩散理论可以解释相关的结论。     

共混顺序对非对称两嵌段共聚物增容体系微观形貌的影响和机理探究

研究了熔融共混过程中共混顺序对非对称的聚苯乙烯-b-聚甲基丙烯酸甲酯嵌段共聚物(PS-b-PMMA,分别命名为SM1和SM2)增容聚苯乙烯/聚甲基丙烯酸甲酯(PS/PMMA)共混体系微观形貌的影响.扫描电镜(SEM)结果发现:合适的共混顺序可以导致分散相相尺寸的明显降低.为研究其增客机理,还选择了聚甲基丙烯酸环己酯/聚甲基丙烯酸甲酯(PCHMA/PMMA)共混体系,并以SM1为增容剂.透射电镜(TEM)结果发现:当SM1首先与连续相PCHMA混合再与PMMA混合,几乎全部的嵌段共聚物分散在共混界面上,增容效率极大提高;反之,SM1首先与分散相PMMA混合再与PCHMA共混,胶束形成并存在于PMMA相内,未起到增容作用.     

嵌段共聚物增容共混聚合物的相形貌及胶束迁移行为研究

主要研究了对称性的聚苯乙烯-聚甲基丙烯酸甲酯嵌段共聚物(PS-b-PMMA,简称SM)对聚甲基丙烯酸甲酯/聚甲基丙烯酸环己酯(PMMA/PCHMA)熔融共混体系的增容。采用透射电子显微镜(TEM)表征了SM和PMMA分子量对共混体系微观相形态和胶束迁移行为的影响。研究表明,SM分别在PMMA与PCHMA均聚物中形成不同结构的胶束,当SM在PMMA/PCHMA界面上形成"湿刷"时,SM在PCHMA相中形成的胶束才能迁移到PMMA相中。SM的加入改善了PMMA与PCHMA之间的相容性,但其增容效果取决于SM的分子量。随着分散相PMMA分子量从19kg/mol增加到39kg/mol,PMMA粒子的平均粒径逐渐增加。     

嵌段共聚物在共混体系中的增容作用研究II.PS-b-PMMA对PVC/SBS共混体系相态结构的影响

合成了一系列分子量和单体组成比不同的聚苯乙烯 -聚甲基丙烯酸甲酯两嵌段共聚物 ( PS- b- PMMA)作为PVC/SBS共混体系的增容剂。系统研究了 PVC/SBS的组成比、增容剂的用量以及增容剂的分子结构等因素与共混体系相态结构之间的关系。结果表明 ,增容剂的不同结构对共混体系的相态结构影响很大 ,在所合成的 4种增容剂中 ,分子量相对较小 ,分子内聚甲基丙烯酸甲酯嵌段的分子量与聚苯乙烯嵌段的分子量比较接近的增容剂分子 ,具有更好的增容效果 ,其增容的共混体系具有典型的韧性特征。     

嵌段共聚物在共混体系中的增容作用研究Ⅱ.PS-b-PMMA对PVC/SBS共混体系相态结构的影响

合成了一系列分子量和单体组成比不同的聚苯乙烯-聚甲基丙烯酸甲酯两嵌段共聚物(PS-b-PMMA)作为PVC/SBS共混体系的增容剂.系统研究了PVC/SBS的组成比、增容剂的用量以及增容剂的分子结构等因素与共混体系相态结构之间的关系.结果表明,增容剂的不同结构对共混体系的相态结构影响很大,在所合成的4种增容剂中,分子量相对较小,分子内聚甲基丙烯酸甲酯嵌段的分子量与聚苯乙烯嵌段的分子量比较接近的增容剂分子,具有更好的增容效果,其增容的共混体系具有典型的韧性特征.     

嵌段共聚物在共混体系中的增容作用研究Ⅲ.PS-b-PMMA对PVC/SBS共混体系动态力学行为的影响

采用自制的一系列分子量和单体组成比不同的聚苯乙烯-聚甲基丙烯酸甲酯两嵌段共聚物(PS-b-PMMA)作为PVC/SBS共混体系的增容剂.研究增容剂的用量、PVC/SBS的组成比以及增容剂的分子结构等因素与共混体系动态力学性能之间的关系.结果表明,增容效果与增容剂的分子结构有密切关系,在所合成的4种增容剂中,分子量相对较小,分子内聚甲基丙烯酸甲酯嵌段的分子量与聚苯乙烯嵌段的分子量比较接近的PS-b-PMMA-1和PS-b-PMMA-2对PVC/SBS具有更好的增容效果.     

嵌段共聚物在共混体系中的增容作用研究：Ⅱ.PS—b—P …

合成了一系列分子量和单体组成比不同的聚苯乙烯－聚甲基丙烯酸甲酯两嵌段共聚物（ＰＳ－ｂ－ＰＭＭＡ）作为ＰＶＣ／ＳＢＳ共混体系的增容剂。系统研究了ＰＶＣ／ＳＢＳ的组成比、增容剂的用量以及增容剂的分子结构等因素与共混体系相态结构之间的关系。结果表明,增容剂的不同结构对共混体系的相态结构影响很大,在所合成的４种增容剂中,分子量相对较小,分子内在两烯酸甲酯嵌段的分子量与聚苯乙烯嵌段的分子量比较接近的增容剂分     

共聚物在不相容共混体系中界面行为的Monte Carlo模拟

用自由体积扩散(FVD)算法模拟了不同结构的共聚物在不相容熔融共混体系中的界面行为,模拟结果表明,加入少量共聚物后,共混体系的相分离程度明显降低,从其形貌来看,分散相相区尺寸变得更小,更分散.所有这些表明,加了共聚物作为增容剂后,共混体系的相容性有明显的提高.而交替共聚物比相应的二嵌段共聚物增容效果更好,与文献中报道的实验现象基本吻合.     

PCL-b-PMMA/PEO共混薄膜的微相分离形貌

通过聚氧化乙烯(PEO)与聚己内酯-聚甲基丙烯酸甲酯嵌段共聚物(PCL-b-PMMA)的共混来调节聚己内酯(PCL)与聚甲基丙烯酸甲酯(PMMA)嵌段的微相分离行为。采用原子力显微镜研究了PEO的质量分数和相对分子质量对PCL-b-PMMA/PEO共混薄膜微相分离形貌的影响。结果表明,共混薄膜形成了以PMMA/PEO为连续相,PCL呈柱状微区垂直于薄膜表面的微相分离形貌,PMMA/PEO链段无法在PCL柱状微区上方形成完全覆盖,导致薄膜表面形成许多孔洞。随着PEO含量增加,PCL链段聚集趋势增强,柱状微区尺寸不断增大;随着PEO相对分子质量的增加,PMMA/PEO在PCL微区上方形成的有效覆盖减少,薄膜表面的孔洞数量和尺寸增大;当PEO与不同嵌段比PCL-b-PMMA共混后,随嵌段共聚物中PCL链段体积分数增加,柱状微区向层状形态转变,薄膜表面孔洞消失。     

嵌段共聚物的共混体系中的增容作用研究：Ⅲ.PS—b—P …

采用自制的一系列分子呈和单体组成比不同的聚苯乙烯－聚甲基丙烯酯甲酯两嵌段共聚物（ＰＳ－ｂ－ＰＭＭＡ）作为ＰＶＣ／ＳＢＳ共混体系的增容剂。研究增容剂的用量、ＰＶＣ／ＳＢＳ的组成比以及增容剂的分子结构等因素与共混体系动态力学性能之间的关系。结果表明,增容效果与增容剂的分子结构有密切关系,在所合成的４种增容剂中,分子量相对较小,分子内聚甲基丙烯酸甲基丙烯酸甲酯嵌段的分子量与聚苯乙烯嵌的分子量比较接近的Ｐ     

Compatibility studies of natural rubber/poly(methyl methacrylate) blends by viscometry and phase separation techniques

The compatibility of binary blends of natural rubber (NR) and poly(methyl methacrylate) (PMMA) has been analysed from the viscosity behaviour. For this, the equations developed by both Krighbaum and Wall, and their modified forms by Williamson and Wright, were used. The interaction between polymers in solution has been interpreted qualitatively based on the heat of mixing (ΔH) and interaction parameter (X1). Viscometry and spectroscopy studies and calculation of the heat of mixing and the interaction parameter indicated the heterogeneous nature of NR/PMMA blends. The effects of graft copolymer of natural rubber and poly(methyl methacrylate) (NR-g-PMMA) as an emulsifying agent on the interfacial properties of NR/PMMA blends were studied based on the phase separation behaviour. The demixing behaviour is found to be a function of graft copolymer concentration, mode of mixing, nature of solvent and molecular weight of homopolymers and graft copolymers. The demixing behaviour has been studied by noting the phase separation time and volume of the phase separated region. The addition of graft copolymer decreases the demixing behaviour of the blends. This revised version was published online in November 2006 with corrections to the Cover Date.     

两嵌段共聚物PMMA-b-PHEMA的合成与表征

采用分步法合成了两嵌段共聚物聚甲基丙烯酸甲酯-b-聚甲基丙烯酸-2-羟乙酯.首先以AIBN为引发剂,FeCl<,3>/PPh<,为>催化体系,通过甲基丙烯酸甲酯(MMA)的反向原子转移自由基聚合,得到端基含Cl的聚合物PMMA-Cl,其分子量分布为1.36;然后以此为大分子引发剂,FeCl<,2>/PPh<,3>为催化...     

Processability of PVDF/PMMA blends studied by torque rheometry

The processing characteristic of blends of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA), in different compositions, were studied by torque rheometry. The polymers were mixed in a batch mixer in proportions of 20, 40, 60 and 80% by weight of PVDF, at 190 °C using rotor speeds of 30, 60 and 100 rpm. The results have shown that the increase of the PMMA content improved the processability of the blends, in spite of an increase of the activation energy of flow. Higher speeds of blending caused a reduction of the homogenization blending times of the blends. The PMMA processing at different speeds studied by parallel plate rheometer showed that a similar behavior and did not affect considerably the degradation of PMMA, according the Carreau model.     

纳米铜/PMMA-b-PS的超声合成及有序组装

在超声辐射作用下,以α-溴代丙酸乙酯为引发剂,溴化亚铜/2,2-联吡啶为催化体系,通过原子转移自由基聚合(A-TRP)制备了分子链末端含有一个α-溴原子的聚甲基丙烯酸甲酯(PMMA-Br)。以此为大分子引发剂引发苯乙烯单体进行ATRP反应,制得聚甲基丙烯酸甲酯嵌段聚苯乙烯(PMMA-b-PS)共聚物。通过硼氢化钠还原聚合物体系中的溴化亚铜,从而得到纳米铜/PMMA-b-PS复合粒子。红外光谱(FT-IR)和核磁共振(1H-NMR)表征嵌段共聚物的结构;凝胶渗透色谱(GPC)测定了共聚物的相对分子量和多分散系数;X射线光电子能谱(XPS)证明纳米铜和PMMA-b-PS嵌段共聚物中PMMA之间存在一定的相互作用;通过高分辨透射电子显微镜(HTEM)观察到纳米铜具有诱导聚合物组装的现象。     

α-PSMA共聚物与PMMA共混物的相容性

用浊点测定、傅里叶变换红外光谱、微差扫描热分析和透射电子显微镜等方法研究了苯乙烯-顺丁烯二酸酐交替共聚物(α-PSMA)与聚甲基丙烯酸甲酯(PMMA)的相容性。结果表明:α-PSMA共聚物与PMMA共混物在共混比7/93～30/70范围内相容性得到改善,其原因是由于α-PSMA与PMMA之间存在特殊的相互作用。     

以乙基黄原酸丙酸乙酯为链转移剂的PMMA-b-PS的可逆加成断链转移自由基聚合

将乙基黄原酸丙酸乙酯作为链转移剂,进行甲基丙烯酸甲酯(MMA)的可逆加成断链转移自由基聚合(RAFT),并将得到的产物作为大分子链转移剂,加入第二单体苯乙烯(St)进行扩链反应,制备了PMMA-b-PS嵌段共聚物。通过红外光谱、核磁共振、凝胶渗透色谱、热重分析和差示扫描量热等测试手段对制备的PMMA-b-PS嵌段共聚物进行分析表征。研究表明,第二单体St与大分子链转移剂发生了共聚,形成了嵌段共聚物;制备所得PMMA-b-PS嵌段共聚物的数均相对分子质量明显增加,相对分子质量分布变宽,初始热分解温度明显提高,玻璃化转变温度介于PMMA与PS的玻璃化转变温度之间。     

Effect of grafted polymer species on particle monolayer structure at the air-water interface

We have studied poly(methyl methacrylate)-grafted(PMMA) particle monolayer systems at the air-water interface. In previous papers, we reported that PMMA chains grafted from particles (silica particle and polystyrene latex) were extended on water surfaces. Through observing deposited particle monolayers on substrates using SEM, we have confirmed that PMMA of large molecular weights were either dispersed or arrayed in structure with long inter-particle distances approximately 500 nm. In contrast, low molecular weight PMMA were observed to aggregate upon deposition. We speculated that the difference in morphology in deposited particle monolayers would be attributed to the affinity between the grafted polymer and the substrate. To examine the effect of this affinity three new polymer-grafted silica particles were synthesized with a fairly high graft density of about 0.14 approximately 0.43 nm(-2). As well as PMMA-grafted silica particles (SiO2-PMMA), poly(2-hydroxyethyl methacrylate) and poly(t-butyl methacrylate)--grafted silica particles (SiO2-PHEMA and SiO2-PtBuMA) were also prepared and subjected to pi-A isotherm measurements and SEM observations. These pi-A isotherms indicated that polymer-grafted silica formed monolayer at the air-water interface, and the onset area of increasing surface pressure suggests that the polymer chains are extended on a water surface. However, the morphology of the deposited monolayer is highly dependent on polymer species: SiO2-PHEMA showed that the dispersed particle monolayer structure was independent of grafted molecular weight while SiO2-tBuMA showed an aggregated structure that was also independent of grafted moleculer weight. SiO2-PMMA showed intermediate tendencies: dispersed structure was observed with high grafted molecular weight and aggregated structure was observed with low grafted molecule weight. The morphology on glass substrate would be explaiened by hydrophilic interaction between grafted polymer and hydrophilic glass substrate.