Synthesis Of Chain Giant Molecules And Adjustment Of Surface Functionalization Of Two-dimensional Crystal

The giant molecule is a new type of polymer with"molecular nanoparticle scale".Its basic building block"molecular nanoparticle"is defined as a class of cage-like nanoparticles with precise molecular composition,specific shape and surface functional groups.For example,Polyhedral Oligomeric Silsesquioxane(POSS)and Polyoxometalate(POM),giant molecules can exhibit very rich supramolecular self-assembly behavior in different physical environments,and the phase structure and phase behavior are also extremely rich.This article uses this as a starting point,using the characteristics of the multifunctional groups on the surface of POSS,using"click chemistry"and Michael addition reaction and other organic synthesis methods,designed a series of reactions to achieve rapid and precise synthesis of chain giant molecules,and through supramolecular self-assembly The regulation of its two-dimensional structure is very important for the self-assembly of giant molecules.The specific research contents of this article are as follows:Using BPOSS-Vinyl as raw material to construct the structural element monomer of giant molecule.Through the selection of mercaptoethanol,L-cysteine(N-Fmoc,S-Trityl)and maleimide as raw materials,a series of reactions such as addition,esterification,deprotection and amidation are used to synthesize and construct giant molecules.The structure of the basic monomer,the entire reaction process is to use efficient condensation reaction.Separation and purification by column chromatography,and purity analysis by nuclear magnetic hydrogen spectrum test and simulation results,the study found that each step of the reaction is accurately synthesized.Study on the process of synthesizing chain giant molecules using structural monomers as raw materials.A chain decoupling molecule was synthesized using the"deprotection-addition"strategy,from a"dead end"Fmoc-protected amino group and a"dormant end"trityl protected Based on the thiol-based structural monomer Fmoc NH-BPOSS-ST,the synthetic route was designed to open the"dead end"and"dormant end"respectively,using maleimide as a carrier to connect the structural element monomers of different functional groups.Through this repeated"deprotection-addition"cycle reaction,the molecular length and sequence composition of the chain giant molecules can be accurately controlled,and the purified product can be separated by column chromatography.The results of the nuclear magnetic hydrogen spectrum are consistent with the simulated values.The results of GPC are in accordance with the theoretical design of molecular weight.And the FTIR results show that the absorption peak of siloxane on POSS appears at 1200 cm^-1,indicating that the presence of POSS structure and the characteristic peaks of each functional group can be marked on the figure,further illustrating the success of the design of the chain giant molecule.Various macromolecules have been thermodynamically studied and found that with the increase in the number of macromolecules,the crystallization temperature and melting temperature also increase,and the sample will not be decomposed within 180?,with good thermal stability.Research on self-assembly and surface functionalization behavior of chain giant molecules.The amphiphilic structure is self-assembled by chemically reacting the previously synthesized chain giant molecules with different functional giant molecules(APOSS,HPOSS,POM).Through the adjustment of the crystal growth environment and the polarity of the solvent,the appropriate solvent ratio polarity is selected to provide the necessary environment and driving force for crystal growth.Growth crystals on carbon-coated mica flakes can be found by transmission electron microscopy.The surface of Fmoc-4BP-AP-ST is a regular diamond-shaped nano-sheet structure with a diameter of 4?m.Fmoc-4BP-POM is a diamond-shaped nanoplate with a diameter of 3?m.and there are many black spots on the surface.This is because the atomic number of the metal element in POM is too different from that of oxygen,carbon,and hydrogen,which results in the obvious difference between light and dark under the electron microscope contrast.So you can see bright black spots in the nanosheets.The surface of Fmoc-4BP-AP-ST is a smooth nano-flake structure with irregular shape and a diameter of about 2?m.The experiment shows that all the giant molecules with different functional groups at their ends can form a two-dimensional layered crystal structure,which is of reference significance for future studies.