Effect Of Crystallinity Of Polyethylene Chain In Graft/Block Polymer On Its Self-assembly Morphology

In this paper,We have synthesized a series of crystalline/non-crystalline triblock,graft copolymers based on polyethylene(PE)and polymethyl methacrylate(PMMA)by ADMET,and atom transfer radical polymerization(ATRP),and oxime-olefin click chemistry.And we studied the effect of the crystallinity of the PE chain in the graft/block copolymer on its self-assembly morphology.1.The triblock copolymers of unsaturated polyethylene(PMMAm-b-uPEn-b-PMMAm)and saturated polyethylene(PMMAm-b-PEn-b-PMMAm)were designed and synthesized,the crystallinity of the middle polyethylene block was changed by hydrogenation reaction,and the effect of crystallization on self-assembly morphology was investigated in solvent vapor conditions while maintaining the polymer structure and molecular weight.Studies have shown that selfassembly morphology is affected by solvent vapor annealing time,temperature and other factors,and the crystallinity of the polyethylene block and the polymethyl methacrylate block is an important driving force for the self-assembly of the polymer into micelle aggregates of different morphologies.2.We designed and synthesized a non-equal-graft graft copolymer based on PE backbone and PMMA branch(PEn-g-PMMAm).Among them,due to the disordered arrangement of PMMA branches along the PE main chain,the polyethylene backbone still has certain crystallinity,and the crystallinity of the main chain can be controlled by changing the chain length of the branches.We studied the self-assembly behavior of the above polymers in a toluene/acetone cosolvent.The studies have shown that the increase of acetone content in the solvent leads to the transformation of the self-assembly morphology from spherical to rod-shaped;and the decrease in the crystallinity of the polyethylene backbone affects the size of the aggregate and results in a change in morphology.3.The equidistant graft copolymer with a main chain of unsaturated PE(uPEn-g-PMMAm)and saturated PE(PEn-g-PMMAm)was designed and prepared.The crystallinity of PE was changed by hydrogenation reaction.The effect of PE crystallinity on the self-assembly morphology of the copolymer solution was investigated while maintaining the structure and molecular weight of the copolymer.The studies have shown that the addition of poor solvent(acetone)of PE to the toluene solution of the copolymer causes the micelles to change from spherical to columnar morphology;as the PMMA segment grows,the interaction between hydrophilic PMMA and its good solvent(acetone)increases,and the columnar micelles transform to spherical micelles;and the crystallinity of polyethylene is beneficial to the transformation of spherical micelles into columnar micelles,and the short columnar micelles self-assembled by solvent will undergo "active" self-assembly under the driving force of crystallization of polyethylene crystals.behavior.