【作者】 杨倩；

【导师】 鲁希华；

【作者基本信息】 东华大学 ， 化学， 2025， 硕士

【摘要】 响应性光子晶体是将响应性聚合物与光子晶体结合,由于具有光子带隙特性,往往能够在外加刺激下实现调谐。当受到特定的物理或化学条件作用时,水凝胶会随着外界环境的变化产生体积上的连续改变或发生相转变,从而引起光学特性的显著变化,使得可以直接通过肉眼观察到材料颜色的改变。然而,一些明亮结构色的光子晶体主要靠硬球模型如Si O₂或与一些吸光材料炭黑以及聚多巴胺等材料复合制备。其次,尽管响应性光子晶体水凝胶目前已经大量应用于传感器,但其较低的机械强度仍然限制了其应用的全部潜力。与水凝胶组成相似的离子凝胶由于离子液体的引入有一些提升的性能,因此已经有将响应性光子晶体与离子凝胶结合的研究。但目前尚少且局限于硬球如Si O₂体系,大多数制备了机械响应光子晶体离子凝胶。此外,一些可穿戴光学器件要求可变形光子材料有不变的结构颜色。而现有的拉伸不变结构颜色的光子材料存在有机凝胶无温度响应结构色、PNIPAM光子水凝胶温度响应范围窄的局限。因此制备具有可调温度范围以及可调机械变色响应的光子晶体离子凝胶具有重要意义。本论文通过将NIPAM与不同单体聚合制备出具有较高色彩饱和度的纳米凝胶光子晶体。以此为基础将其锁定在离子液体和水的混合溶液中进一步制备具有明亮结构色以及提升机械性能的光子晶体离子凝胶。进一步探究光子晶体离子凝胶的可调机械响应性与可调温度响应性。最后,基于光子晶体离子凝胶的响应性对其在热管理方面的应用进行了探究。具体内容如下:（1）通过乳液沉淀聚合方法,温敏性单体NIPAM分别与亲水性单体HEAc和折射率较高的NNMA单体聚合制备了PNEA和PNNMA两种纳米凝胶。通过DLS结果表明通过单体、交联剂以及乳化剂含量的调控成功制备了分散性良好的PNEA和PNNMA纳米凝胶。进一步组装成光子晶体后发现PNNMA较PNEA展现出更高的光学强度约60%,由于单体NNMA的折射率较高。对于分散性较好的纳米凝胶可通过高温-低温循环诱导组装成更大晶粒的纳米凝胶光子晶体。同时凝胶具有温度响应性,在高温情况下结构色会消失变白。（2）高色彩饱和度的PNNMA纳米凝胶在相容性好的BMIM Otf离子液体中的相变温度对比于纯水中升高,随着离子液体与水的比例从0:1增加到8:2,其相变温度从34℃增加至72℃。通过IL/H₂O和二次交联单体含量的调整制备了具有一定机械性能和明亮结构色的光子晶体离子凝胶。通过光谱表明当离子液体与水的比例降至2.9:1同时单体含量为11wt%时,光子晶体离子凝胶的结构色较明亮,并且通过应力-应变曲线发现光子晶体离子凝胶表现出良好的断裂伸长率,接近364%。此外,光子晶体离子凝胶在不同材质上具有一定的黏附性,这可能与离子液体引入带来的氢键、静电相互作用以及离子-偶极相互作用有关。（3）光子晶体离子凝胶展示了可调的机械变色性能和温度响应性。通过调整二次交联单体含量为15-17wt%可制备在应变下的保持稳定结构色的凝胶。由于纳米凝胶的自身的可变形性和在特定单体比下的松散分布,使得其在机械应变作用下变化不显著。对于温度响应性,光子晶体离子凝胶中离子液体和水的比例从2.0:1增加至3.6:1时凝胶的变色温度会从35℃增加至50℃。此外,凝胶的厚度从3 mm降低至1 mm时,变色温度也降低至43℃,因为热传导的速率增加,同时比表面积增加,加速凝胶的升温。不同粒径的光子晶体离子凝胶在升温过程中均表现为蓝移。这是由于随着温度的升高,PNIPAM中的酰胺基脱水,异丙基之间的疏水作用增加,使得凝胶间的晶格间距减小,使得相应得波长减小。此外,由温度响应光子晶体离子凝胶与碳纳米管（PIG-CNTs）薄膜集合而成的复合热管理器件不仅表现出电热转换性能,而且具有直接捕获视觉信号的能力。更多还原

【Abstract】 Responsive photonic crystals are a combination of responsive polymers and photonic crystals,which are materials with photonic bandgap characteristics and can be tuned by external stimuli.Under the stimulation of corresponding physical or chemical conditions,hydrogels undergo continuous volume changes or phase transitions as the external environment changes,which can cause significant variations in their optical properties and often result in observable color changes of the material directly with the naked eye.However,some bright structural color photonic crystals are mainly prepared by hard sphere models such as Si O₂ or by compositing with some light-absorbing materials like carbon black and polydopamine.Secondly,although responsive photonic crystal hydrogels have been widely applied in sensors at present,their relatively low mechanical strength still restricts the full potential of their applications.Ionic gels with similar compositions to hydrogels have some enhanced properties due to the introduction of ionic liquids.Therefore,there have been studies on combining responsive photonic crystals with ionic gels.However,currently,such research is scarce and limited to hard spheres such as SiO₂systems.Most of the ionic gels prepared are mechanical-responsive photonic crystals.Furthermore,some wearable optical devices require deformable photonic materials with invariant structural colors.However,the existing photonic materials with invariant structural color upon stretching have limitations such as the absence of temperature-responsive structural colors in organic gels and the narrow temperature response range of PNIPAM photonic hydrogels.Therefore,the development of photonic crystal ionogels with adjustable temperature ranges and tunable mechanical color-change responses is of great significance.In this paper,nanogel photonic crystals with high color saturation were prepared by polymerizing NIPAM with different monomers.Based on this,they were immobilized in a mixed solution of ionic liquid and water to further prepare photonic crystal ionogels with bright structural colors and enhanced mechanical properties.Finally,the responsiveness of photonic crystal ionogels has been explored for their application in thermal management.The specific details are as follows:（1）The synthesis of PNEA and PNNMA nanogels was achieved through emulsion precipitation polymerization,wherein the temperature-sensitive monomer NIPAM was copolymerized with hydrophilic HEAc and high-refractive-index NNMA monomers.The results of DLS showed that PNEA and PNNMA nanogels with good dispersion were successfully prepared by adjusting the content of monomer,crosslinker and emulsifier.When further assembled into photonic crystals,it was found that PNNMA exhibited about 60% higher optical intensity than PNEA,due to the higher refractive index of monomer NNMA.Good dispersibility of nanogels can be induced to assemble into larger grain-sized nanogel photonic crystals through high-low temperature cycling.At the same time,the gel exhibits temperature-responsive properties,and the structural color will disappear and become white at high temperature.（2）The phase transition temperature of PNNMA nanogel with high color saturation in BMIM Otf ionic liquid with good compatibility is higher than that in pure water.As the ratio of ionic liquid to water increased from 0:1 to 8:2,the phase transition temperature increased from34℃to 72℃.Photonic crystal ionogels with certain mechanical properties and bright structural color were prepared by adjusting the content of IL/H₂O and secondary crosslinked monomer.Spectroscopic analysis revealed that when the ratio of ionic liquid to water was reduced to 2.9:1and the monomer content was 11 wt%,the structure color of photonic crystal ionogel exhibited bright structural color.Stress-strain curves indicated that the photonic crystal ionogel had a good elongation,which is close to 364%.Additionally,the photonic crystal ionogels exhibited some adhesion on different materials,which may be related to hydrogen bonding,electrostatic interactions,and ion-dipole interactions introduced by the ionic liquid.（3）Photonic crystal ionogels demonstrate adjustable mechanical discoloration properties and temperature responsiveness.By adjusting the content of secondary crosslinked monomer to15-17wt%,the gel with stable structure color under strain can be prepared.This was due to the inherent deformability of the nanogels and their loose distribution at specific monomer ratios,which resulted in less significant changes under mechanical strain.For the temperature response,when the ratio of ionic liquid to water in the photonic crystal ionogels increased from 2.0:1 to3.6:1,the color change temperature of the gel increased from 35℃to 50℃.Furthermore,when the gel’s thickness decreased from 3 mm to 1 mm,the transition temperature dropped to 43°C due to increased thermal conductivity and surface area,which accelerated the heating process.The photonic crystal ionogels with different particle sizes all show blue shift during the temperature rise.This is because as the temperature rises,the amide group in PNIPAM dehydrates,and the hydrophobic action between isopropyl groups increases,causing the lattice spacing between gels to decrease and the corresponding wavelength to decrease.In addition,the composite thermal management device,which is composed of temperature-responsive photonic crystal ionogels integrated with carbon nanotube（PIG-CNTs）films,not only exhibits electrothermal conversion performance,but also has the ability to directly capture visual signals.更多还原