| Liquid crystal microcapsule have the advantage of stabilizing the internal liquid crystal and inhibit its fluidity to protect it from environment.Liquid crystal microcapsule has small volume,and it's?easy to storage and be transported.The wall materials of liquid crystal microcapsules provide a stable environment for the internal liquid crystal,which makes the liquid crystal microcapsules exhibit a variety of liquid crystal characteristics.It has great potential in many fields such as laser,display technology,temperature measurement and drug transportation.In this project,the liquid crystal microcapsules with uniform size and controllable size were prepared by combining microcapsules with microfluidic technology.Polymer stabilized cholesteric liquid crystals(PSCLC),cholesterol liquid crystals and nematic liquid crystals were used as the core of the microcapsules respectively to realize the stable"cross communication",the temperature-sensitive color rendering that suitable for human body temperature measurement,and fixed-point pressing color rendering.The specific work is as follows:1.With the PSCLC as the core,liquid crystal microcapsules with high tolerance to environment and"cross-communication"were prepared based on interfacial polymerization.Contrast experiments confirm that the preparation process of liquid crystal microcapsules with intact internal structure can be obtained by adding catalyst at room temperature.Microscopic observation and reflection spectrum measurements show that microcapsules can prevent the overflow of unreacted liquid crystals caused by volume expansion after ultraviolet polymerization and maintain the integrity of liquid crystal structure.By changing the temperature and external media and comparing with liquid crystal droplets,it is concluded that the structure of microcapsules can effectively suppress liquid crystal spillover and improve the tolerance of liquid crystal to external media.2.With cholesterol liquid crystal as the core,liquid crystal microcapsules suitable for temperature measurement,sensitive discoloration and size control were prepared.The liquid crystal mixtures close to human body temperature range can be obtained by mixing COC and CN1 at 1:1.The addition of 10 wt%tetrahydrofuran and 5 wt%acetone reduces the viscosity of liquid crystal mixtures and optimizes the preparation process of microfluidic control.Microencapsulation of liquid crystal by interfacial polymerization can isolate the liquid crystal from the external environment and prevent the influence of the external environment on the temperature sensitivity of liquid crystal.Finally,cholesterol liquid crystal microcapsules with color change of red,yellow,green,blue and purple were obtained in the temperature range of 35.0?37.0?.3.With nematic liquid crystal as the core of the capsule,liquid crystal microcapsules which can be pressed into the polymer network to make them color in the micro-area are obtained.Unlike the traditional method of directly pouring liquid crystals into encapsulated glass boxes with polymer networks,liquid crystal microcapsules can solve the problems of unpredictable liquid crystal flow direction and large color range.By manipulating a single LCD microcapsule and pressing it on the polymer network,the reflective wavelength from the center to the edge was shifted from 560 nm to 460 nm in the order of red,yellow,blue and green.The results show that different filling degree of liquid crystals will lead to different expansion effect of polymers and make the color in the color developing area inconsistent.The color range of liquid crystal microcapsules with diameters ranging from 46 to 131 microns was measured after pressing.With the increase of microcapsule volume,the color range increased from 30147.23 ?m2 2 to 46763.47 ?m2,and the increase ratio decreased from 16.66 to 2.77.It shows that it is feasible to use liquid crystal microcapsules to achieve small-scale and fixed-point polymer network color rendering. |
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