Hamley I W, Castelletto V, Parras P, Lu Z B, Imrie C T, Itoh T
School of Chemistry, University of Reading, Reading, UKRG6 6AD.
Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, UKAB24 3UE.
Soft Matter. 2005 Oct 21;1(5):355-363. doi: 10.1039/b510512a.
Hierarchical ordering in a side group liquid crystal block copolymer is investigated by differential scanning calorimetry, polarized optical microscopy, small-angle X-ray and neutron scattering (SAXS and SANS) and transmission electron microscopy (TEM). A series of block copolymers with a range of compositions was prepared by atom transfer radical polymerization, comprising a polystyrene block and a poly(methyl methacrylate) block bearing chiral cholesteryl mesogens. Smectic ordering is observed as well as microphase separation of the block copolymer. Lamellar structures were observed for far larger volume fractions than for coil-coil copolymers (up to a volume fraction of liquid crystal block, = 0.8). A sample with = 0.86 exhibited a hexagonal-packed cylinder morphology, as confirmed by SAXS and TEM. The matrix comprised the liquid crystal block, with the mesogens forming smectic layers. For the liquid crystal homopolymer and samples with high , a smectic-smectic phase transition was observed below the clearing point. At low temperature, the smectic phase comprises coexisting domains with monolayer S coexisting with interdigitated S domains. At high temperature a S phase is observed. This is the only structure observed for samples with lower . These unprecedented results point to the influence of block copolymer microphase separation on the smectic ordering.
通过差示扫描量热法、偏光显微镜、小角X射线和中子散射（SAXS和SANS）以及透射电子显微镜（TEM）研究了侧基液晶嵌段共聚物中的分级有序性。通过原子转移自由基聚合制备了一系列具有不同组成的嵌段共聚物，其包含聚苯乙烯嵌段和带有手性胆甾醇型液晶元的聚（甲基丙烯酸甲酯）嵌段。观察到了近晶有序以及嵌段共聚物的微相分离。与线团-线团共聚物相比，观察到层状结构的体积分数要大得多（液晶嵌段的体积分数高达= 0.8）。通过SAXS和TEM证实，= 0.86的样品呈现六方堆积圆柱形态。基质由液晶嵌段组成，液晶元形成近晶层。对于液晶均聚物和高的样品，在清亮点以下观察到近晶-近晶相变。在低温下，近晶相包含共存的区域，单层S与指状S区域共存。在高温下观察到S相。这是较低样品中观察到的唯一结构。这些前所未有的结果表明嵌段共聚物微相分离对近晶有序性的影响。
