树枝状大分子具有高度支化和规整的特殊结构,在生物医药、催化化学等多个领域深具发展前景,但目前其制备均采用化学合成方法.文中发展了一种利用自组装手段构筑树枝状大分子的新方法.通过中心分子4臂-聚乙二醇-金刚烷(4 arm-PEG-Ad)和迭代单元β-环糊精-肉桂(β-CD Ci)以及α-环糊精-己二胺-金刚烷(α-CD-hex-Ad)之间的主客体识别,在水体系中,逐步组装得到超分子树状聚合物.通过动态光散射及透射电镜发现,随着代数增长,超分子树状聚合物在溶液中粒径逐渐变大.由于环糊精与客体基团可响应温度变化产生解包舍,这种树状超分子结构在温度上升到60℃以上时会发生瓦解,超分子树状聚合物的粒径由最初的单分散性变为多分散性.
Dendrimers have great potential in biomedical materials,catalysis chemistry,and other applications due to their hyperbranced and regular structure.However,up to now,most dendrimers were prepared by chemical synthesis.In this study,a self-assembly method was developed to fabricate dendrimers.Using the host-guest interactions between 4 arm-polyethylene glycol-adamantane (PEG-Ad),β-cyclodextrin-lysine-cinnamon(β-CD-Ci),and α-cyclodextrin-hexamethylenediamine-adamantane (α-CD-hex-Ad),a dendrimeric supramolecular system was obtained by self-assembly step by step in water.Transmission electron microscopy (TEM) and dynamic light scattering (DLS) results show that the sizes of dendrimers increase with the increase of generation.Furthermore,the supramolecular dendrimers would dissociate above 60 ℃ due to the dissociation of cyclodextrin and guest groups.As a result,the size distribution of supramolecules changes from monodispersity to polydispersity.
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