| The unusual physical and chemical properties of many soft matter materials are closely associated with their contained metallic elements.Thanks to the continuous development of synthetic techniques,research on high molecular weight main-chain metallopolymers has made remarkable progress.Compared to traditional organic polymers,incorporation of metallic elements into polymer structures expands the range of properties of metallopolymers,generating distinguished redox,magnetic,optical and catalytic properties.Metallopolymers thus hold a great potential in applications in supramolecular science and nanoscale materials.Polyferrocenylsilanes(PFSs)is a class of most representative metallopolymers.The main chain of PFS is consisted of alternating ferrocene and organosilane units,including complex noncovalent interactions and presenting particular molecular conformations.PFS systems can form various interesting supramolecular ordered self-assembled structures in solution.In this thesis,we carry out a series of detailed theoretical/simulation study of the structural features and supramolecular self-assembly behaviors in PFS-based soft matter systems from microscopic to mesoscopic scale.Our work aims at deepening the understanding of physical principles underlying the rich multiscale structures and supramolecular self-assembly behaviors in PFS systems,providing theoretical interpretations for experimental results at each structural level,and offering rational guidance to the further control of properties of PFS-based supramolecular materials.The research contents of the thesis are divided into the following three parts:(1)At first,we place our attention on the molecular and single-chain structural properties of poly(ferrocenylmethylsilane)(PFDMS)which is the most representative PFS polymer.We combine quantum chemical and rotational isomeric state(RIS)model calculations to complete the first detailed quantitative study of local molecular conformations and single-chain configurational statistics of PFDMS.We use high-precision density functional theory to determine various low-energy dimeric and trimeric PFDMS oligomer states,which provide accurate input information for the further chain configurational statistics calculations.We apply the classical RIS theoretical approach to calculate important chain configurational properties.The special molecular geometry and interactions of PFDMS are addressed based on some novel treatments in constructing the RIS chain,including the introduction of one pseudoatom and two pseudobonds,and wider length scale of short-range interactions than common polymer RIS model.Several crucial quantities such as the characteristic ratio,Kuhn length and temperature coefficient of PFDMS are predicted for the first time.Our results clarify the relationship between microscopic conformations and chain configurational properties of PFDMS,giving a clear and accurate description of the microscopic structures presented in melt(particularly in the low-energy crystalline state).Our approach is insightful for studying single-chain properties of other complex polymers from theoretical and computational perspective.(2)Next,we focus on studying the self-assembly of crystalline-coil diblock copolymers in solutions(PFDMS-PDMS is a classical example).Due to the directional arrangement of crystalline segments,block polymers containing crystallizable blocks are more likely to form cylindrical micelles,where the crystallization force plays a central role in driving the selfassembly.The self-assembly of crystalline-coil diblock copolymers has been widely studied by experimentalists,but the self-assembly mechanisms and the “large phase window” of nonspherical micellar structures still lack quantitative theoretical interpretations.To this end,we develop a novel “crystalline core-interface-corona”(CCIC)free energy theory and derive the thermodynamic free energy formulas for four types of commonly observed micellar structures constructed by crystalline-coil copolymers: lamella,tube,rod and sphere.The theory includes the “chain folding” crystallization mechanism and predicts the theoretical phase diagrams for three different types of semi-crystalline block copolymer solution systems.Our theoretical predictions are consistent with hallmark experimental trends in crystalline-coil systems.The theory holds the potential to be generalized to broader crystallization-driven self-assembly(CDSA)systems.(3)CDSA and shell cross-linking methods can prepare a variety of novel comicelle structures in solution.Existed experimental reports focused on using PFS as crystallizable polymer to provide crystallinity driving force for maintaining the comicelle structures.Such comicelles are well-defined and have stable structure,which can further form various interesting supramicelle structures via self-assembly.Due to the limitations of experimental methods and characterization techniques,the main sources of supramicelle hierarchical structures and the regulation rules have not been systematically studied.In the end of this thesis,we develop a coarse-grained rod-shaped particle model,and based on Brownian molecular dynamics simulation to study a class of supramicelle systems constructed by amphiphilic cylindrical comicelles.We deeply investigate the influence of the solvent properties,comicelle concentration and comicelle block ratio to the supramicelle structures,and perform preliminary analysis to the comicelle aggregation process.Our simulation results agree well with experimental observations.Furthermore,they reveal additional structural details beyond the experimental precision,such as the finding of interesting helical comicelle arrangements in some rod-like supramicelle structures.Our research provides valuable insights to the construction of large-scale supramolecular self-assembled structures based on CDSA-type comicelles. |
PDF Full Text Request