基于甲壳型液晶高分子的刚-柔型二嵌段共聚物的层状相:链伸展行为的研究

发布时间：2019-01-12 09:41

【摘要】：研究了一系列以聚己内酯(PCL)为柔性链段、甲壳型液晶高分子聚{2,5-二[(4-甲氧基苯基)氧羰基]苯乙烯}(PMPCS)为刚性链段的刚-柔型二嵌段共聚物(PCL-b-PMPCS)的微相分离结构.小角X射线散射(SAXS)和广角X射线衍射(WAXD)实验结果表明,当PMPCS为无定形态时,PCL-b-PMPCS的微相分离行为与柔-柔型二嵌段共聚物相似,其相形态主要取决于两段的体积分数.随温度升高,PMPCS链段采取伸展的棒状构象,形成六方柱状向列相(ΦHN),会诱导体系的微相分离结构出现"有序-有序"或"无序-有序"转变,使得在很宽的PMPCS体积分数(fPMPCS:40%~80%)内样品均呈现层状微相分离结构.我们对在200oC得到的层状相SAXS数据进行了一维相关函数分析,详细考察了层状相中PMPCS及PCL相区的厚度(LPMPCS、LPCL)与相应链段聚合度(NPMPCS、NPCL)的关系.对PMPCS相区,发现LPMPCS=0.2NPMPCS(nm).因棒状PMPCS链段与层的法线方向平行,该线性关系表明PCL-b-PMPCS的层状相为"单层近晶A相"结构,LPMPCS即为棒状PMPCS链段的长度,可通过控制PMPCS的聚合度予以精确控制.对PCL相区,则LPCL与NPCL近似有标度关系LPCL~NPCL0.85,说明处于熔融态的PCL链段受迫强烈伸展.进一步分析WAXD实验数据并计算每根PMPCS链段在层状相中的界面面积(S/X)可知,随NPMPS增大,PMPCS链段的液晶度从~20%增至~55%,S/X则从~2.4nm2增至~2.7 nm2.与此相应,PCL链段的伸展程度会略有降低,说明LPCL有较弱的NPMPCS依赖性.另一方面,LPCL与S/X的乘积与NPCL满足线性关系LPCL(S/X)=0.21NPCL(nm3),斜率即为PCL重复单元的体积.
[Abstract]:A series of polycaprolactone (PCL) flexible segments were studied. The crustacean liquid crystal polymer {2o 5- bis [(4-methoxy phenyl) oxo carbonyl] styrene} (PMPCS) is the microphase separation structure of rigid-flexible diblock copolymer (PCL-b-PMPCS) with rigid chain segments. The experimental results of small angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) show that when PMPCS is amorphous, the microphase separation behavior of PCL-b-PMPCS is similar to that of flexible diblock copolymers. The phase morphology mainly depends on the volume fraction of the two segments. With the increase of temperature, the PMPCS segment takes an extended rod conformation to form a hexagonal columnar nematic phase (桅 HN), induces a "order-ordered" or "disordered" transition of the microphase separation structure of the system. The microphase separation structure of the samples in a wide PMPCS volume fraction (fPMPCS:40%~80%) is layered. The one-dimensional correlation function analysis of the SAXS data of layered phase obtained by 200oC is carried out, and the relationship between the thickness (LPMPCS,LPCL) of PMPCS and PCL phase region and the corresponding degree of polymerization (NPMPCS,NPCL) in layered phase is investigated in detail. For PMPCS phase region, LPMPCS=0.2NPMPCS (nm). Was found. Because the rod-like PMPCS segment is parallel to the normal direction of the layer, the linear relationship shows that the layered phase of PCL-b-PMPCS is a "monolayer near-crystalline A phase" structure, and LPMPCS is the length of the rod-like PMPCS segment, which can be precisely controlled by controlling the degree of polymerization of PMPCS. For the PCL phase region, there is an approximate scaling relationship between LPCL and NPCL. LPCL~NPCL0.85, indicates that the PCL segment in the molten state is forced to extend strongly. Further analysis of the WAXD experimental data and calculation of the interface area (S / X) of each PMPCS segment in the layered phase show that with the increase of NPMPS, the liquid crystal degree of the PMPCS segment increases from ~ 20% to ~ 55% S / X from ~ 2.4nm2 to ~ 2.7 nm2.. Accordingly, the extension of PCL segment will decrease slightly, indicating that LPCL has a weak NPMPCS dependence. On the other hand, the product of LPCL and S / X satisfies the linear relationship with NPCL LPCL (S / X) = 0.21NPCL (nm3), and the slope is the volume of PCL repeating unit.
【作者单位】：北京大学化学学院高分子化学与物理教育部重点实验室;中石化北京化工研究院材料科学研究所;
【基金】：国家自然科学基金(基金号20990232,21634001)资助项目
【分类号】：O631.1;O753.2

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