Research On The Preparation Of Polymer Stabilized Liquid Crystal And Its Electro-optical Properties

Polymer Stabilized Liquid Crystal(PSLC)is an important electro-optical device,which has the characteristics of wide view angle,low energy consumption and no need of polarizers.It has wide application prospects in display,smart windows,light shutters,tunable lenses,phase modulators and many other fields.At present,there are still some problems existing in PSLC,such as high preparation cost and low stability of electro-optical performances,which restrict the development and application of this electro-optical device.In the present paper,UV photo-initiated polymerization-induced phase separation was used to prepare PSLC.The influences of curing conditions(curing time and curing light intensity)on the electro-optical performances of PSLC device were studied.The influences of monomer composition(monomer concentration and monomer species)on the electro-optical properties of PSLC were studied.Stearic acid was used to prepare liquid crystal vertical alignment layer by means of self-assembly,and the electro-optical properties of PSLC prepared by different kinds of alignment layers were compared.The main contents and results are as follows.(1)PSLC devices were fabricated under different curing time.When curing time is too short,the threshold voltage and saturation voltage is relatively low,whereas complete polymer networks cannot be formed in PSLC.When curing time is 300 s,the photo-polymerization reaction is sufficient and complete polymer networks are achieved,threshold voltage and saturation voltage increase.(2)The influence of curing light intensity on the electro-optical properties of PSLC was studied.With the increase of curing light intensity,the threshold voltage and saturation voltage increase.(3)PSLC devices were prepared at different monomer concentrations.When the concentration of monomer is low,the threshold voltage and saturation voltage are low,but the response time is long,fog state exists on PSLC device after electrical field is removed.With the increase of monomer concentration,the threshold voltage,saturation voltage and opening time increase,but the closing time decreases.(4)Lauryl acrylate,a kind of non-liquid crystalline monomer,was added into the liquid crystalline monomer HCM009 to prepare PSLC.When the mass fraction of lauryl acrylate is 1wt% and the mass ratio of lauryl acrylate to HCM009 is 1:5,the opening time of PSLC reduces significantly,threshold voltage and saturation voltage decrease,while the closing time increases.With the increase of amount of lauryl acrylate,the stability of PSLC electro-optical properties become worse.(5)Liquid crystal vertical alignment layer was fabricated by self-assembly of stearic acid.By using this method,liquid crystal cell can achieve a pretilt angle of 89.9°.Compared with PSLC aligned by polyimide,the transmittance-voltage relationship of stearic acid aligned PSLC is basically the same as that of polyimide aligned PSLC.When the driven voltage is 60 V,the closing time of stearic acid aligned PSLC is too long(3.228s),while at the driven voltage of 25 V,the response time of PSLC improves significantly.