【摘要】：聚合物穩(wěn)定膽甾相液晶(polymer-stabilized cholesteric texture,PSCT)在一定條件作用下,其網(wǎng)絡(luò)形貌會發(fā)生形變。聚合物網(wǎng)絡(luò)形變會導(dǎo)致液晶取向,螺距梯度和網(wǎng)絡(luò)錨定力等發(fā)生改變,從而對器件的性能產(chǎn)生重要影響。由于聚合物網(wǎng)絡(luò)尺度微小,形變程度難以表征。采用掃描電子顯微鏡(scanning electron microscope,SEM)和共聚焦顯微鏡(confocal microscope)等手段可以觀察網(wǎng)絡(luò)形貌,但是往往要破壞器件結(jié)構(gòu),且不能表征網(wǎng)絡(luò)形變的動態(tài)過程。聚合物穩(wěn)定膽甾相液晶,其動態(tài)響應(yīng)過程源于液晶局部指向矢(local director)的重新排列。這一過程由介電耦合效應(yīng)(dielectric coupling effect) /自組裝效應(yīng)(self-assembly effect)和聚合物網(wǎng)絡(luò)形變(polymer network deformation)來主導(dǎo)。使用雙指數(shù)模型來擬合動態(tài)響應(yīng)的實測數(shù)據(jù),能擬合的很好,擬合度達(dá)到99%以上。通過對動態(tài)響應(yīng)瞬間上升和下降過程的模擬,聚合物網(wǎng)絡(luò)形變的程度可以被定量的計算出來。通過調(diào)節(jié)驅(qū)動電場強度,驅(qū)動信號頻率,環(huán)境溫度和單體濃度可以控制聚合物網(wǎng)絡(luò)的形變程度。在一定范圍內(nèi),降低驅(qū)動電場強度、提高驅(qū)動信號頻率、降低環(huán)境溫度或增大單體濃度能分別減弱聚合物網(wǎng)絡(luò)形變的程度。降低聚合物網(wǎng)絡(luò)形變程度和提高網(wǎng)絡(luò)形變回復(fù)速度能有效地抑制遲滯(hysteresis)效應(yīng);在其他條件相同的情況下,更小的網(wǎng)絡(luò)形變還能縮短撤電響應(yīng)時間(field-offresponse time)。以上研究結(jié)果,為制備PSCT器件和優(yōu)化其性能提供了積極有益的指導(dǎo)。
[Abstract]:The network morphology of polymer stabilized cholesteric liquid crystal (polymer-stabilized cholesteric) will deform under certain conditions. The deformation of polymer network will lead to the change of liquid crystal orientation, pitch gradient and network anchoring force, which will have an important impact on the performance of the device. Because the scale of polymer network is small, it is difficult to characterize the degree of deformation. Scanning electron microscope (scanning electron) and confocal microscope (confocal microscope) can be used to observe the morphology of the network, but the device structure is often destroyed and the dynamic process of network deformation can not be characterized. The dynamic response of polymer stabilized cholesteric liquid crystal is due to the rearrangement of the local directional vector (local director) of the liquid crystal. The process is dominated by dielectric coupling effect (dielectric coupling effect) / self-assembly effect) and polymer network deformation (polymer network deformation). Using the double exponential model to fit the measured data of dynamic response can fit well, and the fitting degree is over 99%. The degree of deformation of polymer networks can be quantitatively calculated by simulating the transient ascending and descending process of dynamic response. The deformation degree of polymer networks can be controlled by adjusting the driving electric field intensity, driving signal frequency, ambient temperature and monomer concentration. In a certain range, the degree of polymer network deformation can be reduced by decreasing the driving electric field intensity, increasing the driving signal frequency, lowering the ambient temperature or increasing the monomer concentration. Reducing the degree of polymer network deformation and increasing the recovery rate of network deformation can effectively suppress the hysteresis (hysteresis) effect, and the smaller network deformation can also shorten the response time (field-offresponse time).) under the same conditions. These results provide useful guidance for PSCT device fabrication and performance optimization.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O753.2

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