Study On Synthesis,Structure And Properties Of Brush-like Thermoplastic Elastomer Based On Cellulose

Cellulose is a rich renewable natural resource in the world and has a wide range of application prospects.Reasonable and effective use of cellulose can effectively alleviate the energy crisis.The covalent modification of cellulose can endow it with grafting copolymer properties.In this paper,biodegradable cellulose is used as a rigid backbone grafted polymer side chain to obtain a cellulose grafted thermoplastic elastomer.The focus of this research is to control the molecular structure,micro structure and mechanical properties by controlling the side chain composition,molecular mass and graft density.Explore the dependence of changes in the internal microstructure of the material system on the structure of the molecular chain,and establish the relationship between structure and performance.The main content includes the following aspects:1.Select cellulose as the rigid backbone,use the modified cellulose as the macroinitiator(Cell-BiB),adopt the method of atom transfer radical polymerization(ATRP),and use n-butyl acrylate(BA)as the monomer of the soft segment obtains cellulose-graft-poly(n-butyl acrylate)(Cell-g-PBA).Subsequently,Cell-g-PBA was used as the macroinitiator to initiate the ATRP polymerization of methyl methacrylate(MMA)monomer using halogen exchange technology,and finally obtained cellulose-graft-poly(n-butyl acrylate)-block-poly(methyl methacrylate)bottlebrush thermoplastic elastomer(Cell-g-PBA-b-PMMA).The dates of FTIR,NMR and DSC characterization methods indicate that we have successfully prepared a series of thermoplastic elastomers with different molecular weights.The relationship between the microphase separation structure and the macroscopic mechanical properties was explored by AFM,SAXS and mechanical properties.AFM micrographs show that the internal microstructure of all samples is columnar microstructure.With the increase of PMMA chain length,the modulus and mechanical strengths at break of elastomer increase,while with the increase of PBA chain length,the elasticity and resilience of elastomer are enhanced.2.By controlling the molecular chain length of PBA and PMMA,the mechanical properties of Cell-g-PBA-b-PMMA bottlebrush thermoplastic elastomer can be adjusted.A series of thermoplastic elastomers with longer PBA molecular chains were prepared,and it was found that the series of thermoplastic elastomers had a mechanical behavior similar to that of human and animal skin after being subjected to a step-cyclic tensile deformation at room temperature.The immiscibility of the two components of PBA and PMMA in the grafted side chain leads to the self-assembly of PMMA to form physical cross-linking points.The long-chain PBA block gives the thermoplastic elastomer good elasticity and recovery.The chain length of the PMMA block can regulate its tensile strength.TGA dates prove that the bottlebrush thermoplastic elastomer has good thermal stability.The rigid PMMA microphones and the soft PBA matrix act as rigid and elastic components in the skin,respectively,giving the elastomer sufficient tensile strength and elastic recovery.SAXS and TEM confirm the orientation of the nanofiber microstructure in the stretching-treated elastomer.The study of bionic polymer materials is crucial to the development of other bionic polymer materials in the future.3.As the rigid backbone of the bottlebrush,cellulose has a vital influence on the properties of bottlebrush thermoplastic elastomers.In order to study the effect of cellulose on the structure and properties of thermoplastic elastomers,a series of bottlebrush thermoplastic elastomers with higher cellulose content and shorter grafted side chains(below the critical entanglement molecular weight)were prepared.The effect of cellulose content and side chain molecular mass on the microscopic phase separation structure and macroscopic tensile properties were studied.DSC and DMA prove that the microphase separation occurred in the thermoplastic elastomer system.AFM micrographs intuitively show that the microphase separation structure is transitioned from spherical to cylindrical with the gradual increase in molecular weight of PMMA.The SAXS curves reveal that the cellulose backbones play an important role in the mechanical properties during the tensile process.4.Cellulose,PBA and PMMA play different roles in the bottlebrush polymer system.Therefore,by controlling the content of cellulose,PBA and PMMA,the microphase separation structure and various properties of the bottlebrush polymer elastomer can be adjusted.This chapter uses small-angle X-ray scattering(SAXS)to study in detail the dynamic changes in the microstructure of the short side chain bottlebrush polymer elastomer system with high cellulose content during the tensile g process,and explore the mechanism of short side chain bottlebrush polymers with good mechanical properties.The results show that the hard phase region of PMMA and cellulose backbone were aligned during the drawing process,which provided rigidity and strength for the bottlebrush polymers.