Study on Synthesis,Properties and Applications of Hyperbranched Polyethylene-g-polymath-Acrylates-based Polymers

Author:Deng Zheng

Supervisor:wang li yu hao jie

Database:Doctor

Degree Year:2018

Download:393

Pages:181

Size:20579K

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Hyperbranched polyethylene exhibits unique branched topology and properties.However,hyperbranched polyethylene lacks polar functionality,which limited its further application.Introduction of polar functionality into hyperbranched polyethylene via graft polymerization method can extend its application scope.Herein,in this thesis,a series of hyperbranched polyethylene grafted-based polymethacrylates polymers were synthesized through a combination of coordination polymerization and atom transfer radical polymerization.Their application in self-assembly nano-materials,anti-migration burning rate catalyst and carbon nanotube dispersant were studied respectively.1.HBPE-g-PFcEMA was synthesized and characterized.Then,the self-assembly behaviors of HBPE-g-PFcEMA with different concentration were studied in THF/n-hexane and n-hexane respectively.It was found that solvent properties have significant effects on the self-assembly behavior of HBPE-g-PFcEMA.In THF/n-hexane,HBPE-g-PFcEMA micelles with specific morphology were obtained at low polymer concentration.But,no regular HBPE-g-PFcEMA micelles was obtained at higher polymer concentration.In n-hexane,HBPE-g-PFcEMA micelles with various morphologies(e.g.unimolecular micelle,micellar sheet,hollow micro-sphere and patchy sphere)were obtained via adjusting the concentration(varied from 0.1-10.0 mg/mL)of HBPE-g-PFcEMA.2.HBPE-g-PFcEMA was synthesized as burning rate catalyst for solid propellant.It was found that HBPE-g-PFcEMA exhibited excellent thermal stability under 210 ℃.Besides,HBPE-g-PFcEMA showed excellent electro-chemical properties.According to TGA results,HBPE-g-PFcEMA was able to effectively accelerate the high-temperature thermal decomposition of AP,meanwhile lower its final decomposition and maximum weight loss temperature of 78 ℃ and 80 ℃ respectively.Furthermore,based on anti-migration results,we concluded that HBPE-g-PFcEMA was an efficient anti-migration burning rate catalyst.3.HBPE-g-PFcEMA was synthesized as a non-covalent dispersant for MWCNTs.The dispersibility of MWCNTs employing HBPE-g-PFcEMA was evaluated via TGA,UV-vis,TEM and SEM technology.These results indicated that MWCNTs were effectively dispersed with a maximum MWCNTs concentration of 150.4 mg/L.Existence of π-π stacking interactions between HBPE-g-PFcEMA and MWCNTs was proved by UV-vis results.Then,HBPE-g-PFcEMA/MWCNTs/PET composite film was fabricated and its conductivity was measured to be 0.0943 S cm-1,which might find its potential application in electronic devices.4.HBPE-g-PtBMAwas synthesized and characterized.Then dispersing MWCNTs by HBPE-g-PtBMA in CHCl3 was studied.It turned out that the mass ratio of HBPE-g-PtBMA/MWCNTs had remarkable influence on the concentration of MWCNTs.The maximum concentration was achieved when HBPE-g-PtBMA/MWCNTs=2.0.According to the TEM and SEM results,we found that MWCNTs were dispersed into single carbon nanotube by HBPE-g-PtBMA.HBPE-g-PtBMA/MWCNTs/PET composite film was fabricated via spin-coating method.The resultant film exhibited uniform MWCNTs networks and excellent conductivity(13.14 S cm-1).Moreover,the composite film showed good conductivity even it was bent(150°).Furthermore,about 30%increase of the resistance was observed after the composite film being bent and released for 1000 times.5.HBPE-g-PMAA was synthesized and characterized.Then,Then dispersing MWCNTs in water by HBPE-g-PMAA was studied.HBPE-g-PMAA was an amphiphilic polymer which self-assembled into micelles with an average diameter of 30 nm and some micellar aggregates.TEM,AFM and SEM results indicated that HBPE-g-PMAA was able to disperse MWCNTs efficiently.TGA results showed that the concentration(60-135 mg/L)of MWCNTs in water increased as the mass ratio of HBPE-g-PMAA/MWCNTs increased(0.25-5.0).