Preparation,Structure And Properties Of Liquid Crystals Microcapsules

Microcapsulation of liquid crystal is a technology that stabilizes liquid crystal in the film-forming material to broaden the scope of liquid crystal application.It presents advantages of cost saving,ease of processing and mass production,thus shows huge application prospects in dynamic filter,optical switch,flat panel display,information storage,optical communications,security and other areas.However,it remains a great challenge,how to form liquid crystal microcapsules with high liquid crystal loading,low residual impurities,good monodispersity.First of all,liquid crystal microcapsules were formed using P0616 A and SLC123217-200 as the liquid crystals.Microcapsulation helped to disperse,stabilize and protect liquid crystals.By employing methylmethacrylate(MMA),2-(trifluoromethyl)acrylate(MTFMA)and ethylene dimethacrylate(EGDMA)as the monomers,potassium persulfate(KPS)or azobisisobutyronitrile(AIBN)as the initiator,hydrolyzed styrene-maleic anhydride copolymer(HSMA)as the emulsifier,liquid crystals microcapsules with methacrylate polymers as shells were prepared via in situ emulsion polymerization.Using interface sol-gel reaction,tetraethyl orthosilicate(TEOS)and 3-ammoniapropyltriethoxysilane(APTES)as the precursors,HSMA as the emulsifier,liquid crystal microcapsules with Si O2 as shells were prepared under acidic condition.Using interface polymerization method,bisphenol A glycidyl ether epoxy resin(E 51)as the monomer,tetraethylenepentamine(TEPA)or N,N-dimethylbenzylamine(BDMA)as the initiator,epoxy resin and ethylene glycol copolymer(E 325)as the emulsifier,liquid crystal microcapsules with epoxy resin as shells were prepared.The processing conditions of microencapsulation include oil-water ratio,reaction temperature,emulsification time,stirring speed and emulsifier content were optimized by analyzing the morphology,particle size and size distribution of liquid crystal microcapsules.Secondly,differential scanning calorimetry(DSC)was used to study the phase behavior of liquid crystals under chemical and physical confinements.The results show that the phase transition temperature of liquid crystals P0616 A is almost unchanged,while the phase transition temperature of the fluorinated liquid crystals SLC123217-200 is increased because of the interaction with the shell.Finally,the orientation of liquid crystals in a single microcapsule was observed by three-photon fluorescence microscopy.The results show that with the decrease of microcapsule size,the order of liquid crystals was changed from bipolar structure to planar structure.