Morphological Study On Aggregates Of T-type And H-type Rigid And Flexible Amphiphilic Molecules

Functional polymers connected by covalent bonds have a very stable structure,but it is limited tuning the property by changing external conditions.Supramolecular polymers with non-covalent bonds are dynamic reversible and environmentally sensitive,and self-assembled aggregates exhibit significant properties and recycling ability through adaptability and stimulus response,which gives such materials self-healing and multifunctional properties.In many self-assembled systems,rigid and flexible oligomers can form stable supramolecular aggregates in bulk and solution states,due to the microphase separation between flexible and rigid segments and the hydrophilic and hydrophobic interaction in selective solution.A variety of ordered supramolecular aggregates can be prepared by adjusting the synergistic effects of several parameters,such as rigid-flexible volume ratio,rigid or flexible chain length and cross-sectional area of coil segments.Among many nanomaterials,nanofibers belong to one-dimensional nanomaterials with high specific surface area and length-diameter ratio,has the potential applications in materials science.Through the changes of system environments,the molecules can further arrange into various nanostructures,such as nanofiber,singlewalled nanotube,nano cage,helical fiber.Prior to this,although researchers have done a lot of research on nanofibers,but most of these studies are based on the individual nanofiber structure of the material.In this paper,starting from the study of individual nanofibers,H-type and T-type rigid flexible block amphiphilic molecules were designed and synthesized,and their special molecular configurations were used to assemble nanostructures in polar solvents,and on this basis,the functional properties of the assembly were studied.In this thesis,the self-assembly behavior of H-and T-type rigid/flexible block amphiphilic molecules is described in detail.First,a series of H-and T-type rigid/flexible block amphiphilic molecules are designed and synthesized.The experimental results show that by changing the flexible chain length and introducing side chain,supramolecular nanostructures can be controlled,driven by hydrophilic/hydrophobic effect molecular steric hindrance,in the mixed solution of tetrahydrofuran and water.Supramolecular nanostructures such as nanotubes,cage and nano fibers for H-shaped molecules and the nanometer sheet,helical fibers for T-shaped molecules,were constructed in this work.In addition,the mechanism of the transition from onedimensional nanofibers to complex nanostructures has been studied,and these transitions provide hollow nanostructures,which have potential applications in membrane science.We believed that various nanomaterials constructed by rigid/flexible amphiphilic molecules,further used as smart nanoreactor or drug dilivery system,through stimuli of these molecular system in selective solvents.