The Study For The Compatibilization Of Block Copolymer On Incompatible Polymer Blends

Polymer blends has become an economical and convenient way to produce advanced composite materials,while the incompatibility between the components of polymer blends seriously restricts the performance and applications of materials.Moreover,the application of the compatibilization techniques to improve the compatibility of components of polymer blends has significant economic benefits on the development and application of new materials.Block copolymer is always used to compatibilize the immiscible polymer blends due to its special molecular structure.But the block copolymer easily forms micelles in the blends when the micelle concentration is above critical value,which can reduce the compatibilization efficiency of block copolymer.Therefore,the study for the mechanism of block copolymers compatibilizing immiscible polymer blends has important theoretical value and practical significance on the improvement of the compatibilized application of block copolymer.In this thesis,PS-b-PMMA(SM)block copolymers was selected as compatibilizer to prepare the system of poly(methyl methacrylate)/poly(cyclohexyl methacrylate)(PMMA/PCHMA)and polystyrene/poly(methyl methacrylate)(PS/PMMA)via the method of melt blends.The influence of processing conditions,the structures and concentration of SM on the morphology of the blends,block copolymer micellar architectures formed in the blends and migration behavior of block copolymer molecules at the interface of components of polymer blends were systematically studied.Furthermore,the morphology and rheological behavior of the blends were investigated by using transmission electron microscope and rotary rheometer.The main results were as follows:1.The effects of shear rate,mixing time and mixing protocol on the size and distribution of PMMA dispersed phase particles in the blends of SM/PMMA/PCHMA were studied.The results showed that the size of dispersed phase particle was smallest when the shear rate was 100 rpm.The time for the equilibrium of blends reached can be extended by the compatibilizer.The compatibilization efficiency of block copolymer related to the solubility of block copolymer in the components of the blends.When the block copolymer preferentially added to the components with high solubility,the compatibilizing efficiency of the block copolymer was highest.2.The micellar structure of SM formed in the PCHMA and PMMA was compared,and the migration behavior of SM with different molecular weight at the interface of PCHMA/PMMA was investigated.Moreover,the degree of bonding of SM was characterized by using rotary rheometer.The results indicated SM were formed core-corona micelles in the PCHMA and PMMA.The micelle core was PMMA when the PS-b-PMMA was blended with PCHMA,while the micelle core was PS when the PS-b-PMMA was blended with PMMA.When wet brushes were formed by the block copolymer at the interface of the mixed phase,the micelles generated in PCHMA phase were migrated to PMMA phase.The size of dispersed phase particle was smallest when the molecular weight of PS-b-PMMA was 50kg/mol.3.SM with different molecular structure was utilized to compatibilite PMMA/PCHMA and PS/PMMA,and the effects of the content and molecular structure of SM on the morphology of blends were studied.The results showed that PMMA dispersed phase particle size decrease roughly with the increasing content of compatibilizer.SM with the shorter chains can more quickly diffuse to the interface,but could not prevent static coalescence in the annealing.When the chain length of SM is longer than that of the contents of blend,SM can not only decrease the size of dispersed phase particles,but also effectively stabilize the phase morphology of the blends.The longer segment of SM located in dispersion phase can inhibit the rupture of dilute fiber in dispersion phase particles,thereby improved the continuity of the dispersed phase.