聚合物凝胶光子晶体及其对物理环境的响应

文中简要介绍了物理响应性光子晶体的国内外研究动态。重点介绍以下几种物理响应性光子晶体:温度响应性光子晶体,溶剂响应性光子晶体,电场响应性光子晶体,磁场响应性光子晶体,机械力响应性光子晶体等。     

低化学交联反蛋白石水凝胶的制备及多重刺激响应性

将物理交联与化学交联相结合,利用蛋白石结构光子晶体模板法制备了低化学交联的聚N-异丙基丙烯酰胺/丙烯酸(C-dots/BIS-P(NIPAm-AA))反蛋白石结构光子晶体水凝胶(IOH₍P(NIPAm-AA)))。其中,pH敏感性单体丙烯酸(AA)和温敏性单体N-异丙基丙烯酰胺(NIPAm)的引入赋予了IOH₍P(NIPAm-AA))多重刺激响应性。通过扫描电镜表征了IOH₍P(NIPAm-AA))的内部微观结构,探究了共聚单体AA含量对IOH₍P(NIPAm-AA))的影响,并基于结构色的变化来研究IOH₍P(NIPAm-AA))对外部刺激的响应行为。结果表明,低化学交联的IOH₍P(NIPAm-AA))具有规整有序的三维大孔结构。随着共聚单体AA用量从0.54 mL增大到0.9 mL,IOH₍P(NIPAm-AA))的结构色由蓝色转为蓝绿色再变为黄绿色,同时反射光谱发生了明显的红移。IOH₍P(NIPAm-A...     

pH响应性可降解聚(醚酯-氨酯)的制备及在药物缓释领域的应用

设计和制备了一类具有高pH响应性的可降解聚氨酯材料,旨在作为一种智能给药载体。首先通过“硫醇-烯”点击反应合成了一种吡啶基二醇(PyDH);然后,以PyDH、聚醚酯二醇和二异氰酸酯为原料,通过缩聚反应制备了侧链含吡啶基团的聚(醚酯-氨酯)(PEEU-Py),并经溶剂挥发得到相应的薄膜材料。通过核磁共振、红外光谱、凝胶渗透色谱等对PyDH和PEEU-Py的化学结构进行了表征,并对PEEU-Py膜的力学、溶胀、降解、药物缓释等性能进行了研究。PEEU-Py膜展示出高的pH溶胀性,其在pH=1.5介质中的平衡吸水率分别为pH=7.0和pH=11.5的2倍和8倍以上;体外药物缓释研究表明,膜材料的药物释放速率随pH值的降低而提高,其药物释放能力与材料的溶胀性能相一致。此外,细胞毒性评价表明该材料具有良好的细胞相容性。研究结果表明,PEEU-Py作为一种受外界pH变化触发的智能开关在药物载体上有好的应用前景。     

具有pH响应性和成纤性的丙烯腈与丙烯酸共聚物的结构

利用丙烯腈(AN)与丙烯酸(AA)单体的化学性质及单体的活性不同,AA采用不同投料方式,制备了具有pH响应性与成纤性的丙烯腈/丙烯酸共聚物[P(AN-co-AA)],通过红外、液体核磁、元素分析等测试手段研究了共聚物结构特点。结果表明,AA与AN单体物质的量比为20∶80时,聚合物具有良好的pH响应性与成纤性;不同投料方式的共聚物中羰基与氰基含量的比值都随着反应进行呈增长趋势,一次性投料更大;分批投料共聚物分子链易形成嵌段结构,表现出良好的pH响应性及较好的力学性能。     

Poly(DMAEMA-co-VP)/Fe_3O_4纳米复合水凝胶的制备及性能

以甲基丙烯酸-N,N-二甲氨基乙酯(DMAEMA)、4-乙烯基吡啶(VP)为单体,N,N-亚甲基双丙烯酰胺(BIS)为交联剂,在Fe_3O_4纳米粒子分散液中原位共聚制备了具有温度、pH、磁场三重响应性的纳米复合水凝胶。对纳米复合水凝胶的溶胀性能、温敏性、pH敏感性、磁场响应性等性能进行了研究,进而考察了纳米复合水凝胶对重金属离子(Cu~(2+))的吸附脱附行为。结果表明,纳米复合水凝胶具有良好的温敏性、pH敏感性和磁场响应性,并且对重金属离子(Cu~(2+))有可逆的吸附-脱附作用。     

聚合物在pH传感器中的应用

综述了聚合物基pH传感器的研究现状:聚合物作为敏感层、衬底或传输基材广泛应用于最常见的光、电流、电位、电导等pH值传感系统;一些非响应性高分子材料既可作为传感器光纤,也可用于荧光染料的固定。重点介绍了pH敏感性高分子的响应机理即pH敏感性高分子如聚电解质、水凝胶、导电高分子、半导体高分子等对pH值变化具有体积、电导率、阻抗、电位、电流等响应,总结了聚合物基pH传感器在真实测量领域的应用并对聚合物基pH传感器今后的研究趋势进行了分析。     

核壳结构羟基磷灰石/介孔二氧化硅纳米颗粒的制备及其药物释放研究

核壳纳米颗粒是一种具有独特结构和性能的复合纳米材料, 在催化、生物医学和光子晶体等领域具有重要应用前景。本工作以羟基磷灰石(HAp)纳米颗粒作为核体、十六烷基三甲基溴化铵(CTAB)作为介孔模板剂, 采用改进的Stöber包覆法制备具有介孔结构的核壳HAp@mSiO₂新型纳米颗粒。通过控制正硅酸四乙酯(TEOS)的浓度及其水解和缩合动力学, 可以有效调控HAp表面包覆的mSiO₂壳层厚度。经TEM、EDS、XRD、FT-IR及BET一系列测试可知, 制备得到的HAp@mSiO₂纳米颗粒具有比表面积大、孔径尺寸窄且分布均匀等特点。同时, 以布洛芬作为模板药物, 将制备得到的材料应用于药物释放实验, 发现该核壳材料还具有良好的药物控制性能和pH响应特性, 且可以通过改变mSiO₂壳层厚度对药物释放速率进行有效调控。     

聚丙烯酰胺/聚甲基丙烯酸(2-甲基氨基)乙酯高强度双网络水凝胶的制备及pH响应性

利用两步法合成了聚丙烯酰胺(PAM)/聚甲基丙烯酸(2-甲基氨基)乙酯(PDMAEMA)双网络水凝胶,第一网络为锂藻土(Laponite)物理交联的PAM纳米复合水凝胶,第二网络为化学交联剂N,N-亚甲基双丙烯酰胺(BIS)交联PDMAEMA。研究了2种网络相对含量、纳米黏土Laponite用量、化学交联剂BIS用量对水凝胶强度和pH响应性的影响。研究结果表明,PAM/PDMAEMA双网络水凝胶具有高强度,改变单体AM和DMAEMA的配比、交联剂的用量,其拉伸强度在36～91.9 kPa范围内可调。PAM/PDMAEMA双网络水凝胶还具有灵敏的pH刺激响应性,在pH=4时双网络水凝胶溶胀度急剧下降。     

SiO2溶胶对P（St-MAA）光子晶体生色结构的稳固性增强作用

提出采用后填充方式制备兼具稳固性和良好结构色效果的复合光子晶体。通过采用胶体微球自组装法制备图案化聚（苯乙烯-甲基丙烯酸）(P（St-MAA）)光子晶体生色结构,然后利用SiO₂溶胶对P（St-MAA）光子晶体进行填充。优化了SiO₂的填充条件,并对比了填充前后光子晶体生色结构的结构色效果和稳固性变化情况。结果表明:粒径分别为230 nm、250 nm和287 nm的P（St-MAA）胶体微球可构筑得到排列规整、结构色明亮的光子晶体,但晶体层的稳固性不佳;当SiO₂浓度不超过30wt%,填充时间不超过5 min时,可制备得到结构色仍旧较明亮的SiO₂-P（St-MAA）复合光子晶体;在相同的稳固性测试条件下,复合光子晶体稳固性明显提升,结构色效果不易消减,这主要归因于SiO₂起到了类似"桥梁"的作用,加强了相邻P（St-MAA）胶体微球间的黏连,并增强了光子晶体层与基材间的黏性。本研究将为构筑高质量光子晶体提供新思路,有望推动光子晶体生色结构的实际应用。     

P(HEMA-co-MAA)纳米凝胶的制备与pH响应性

以甲基丙烯酸羟乙酯(HEMA)和甲基丙烯酸(MAA)为聚合单体,异辛烷为分散介质,Span80和Tween80为复配乳化剂,采用反相微乳液聚合法制得不同单体配比的聚(甲基丙烯酸羟乙酯-co-甲基丙烯酸)(P(HEMA-co-MAA))纳米凝胶。确定了产物的pKa值及实际单体物质的量比,对产物的形貌进行了表征并研究了产物的pH响应性.结果显示,MAA物质的量分数为20%的纳米凝胶的pKa值为5.83,在pH=3和pH=7时其数均粒径分别为48 nm和90 nm;当环境pH接近pKa值时,纳米凝胶分散液的浊度明显降低,溶胀率明显上升,表观黏度急剧增加,说明纳米凝胶具有良好的pH响应性。     

Preparation of P(St-NMA) microsphere inks and their application in photonic crystal patterns with brilliant structural colors

Patterned photonic crystals with structural colors on textile substrates have attracted a special attention due to the great advantages in application, which currently become a research hot-spot. This study utilized an ink-jet printing technology to prepare high-quality photonic crystal patterns with structural colors on polyester substrates. The self-assembly temperature of poly(styrene-N-methylol acrylamide) (P(St-NMA)) microspheres set to construct photonic crystals were deeply optimized. Moreover, the structural colors of prepared photonic crystal patterns were characterized and evaluated. When the mass fraction of P(St-NMA) microspheres was 1.0 wt.%, the pH value ranged from 5 to 7, and the surface tension was in the range of 63.79 to 71.20 mN/m, inks could present the best print performance. At 60 °C, prepared P(St-NMA) microsphere inks were good for printing to obtain patterned photonic crystals with regular arrangement and beautiful structural colors. Specifically, photonic crystals with different colors could be constructed by regulating the diameter of microspheres in inks, and prepared structural colors exhibited distinct iridescent phenomenon. The present results could provide a theoretical basis for the industrial realization of patterned photonic crystals by ink-jet printing technology.     

Thermal Responsive Photonic Crystal Achieved through the Control of Light Path Guided by Phase Transition

Responsive photonic crystal is widely considered in the field of anti‐counterfeiting and information encryption because of their structural color changes caused by external stimulation. However, the response signal is usually achieved by adjusting the periodic lattice constant based on Bragg's law with volume changes. Thus, it is a great challenge to achieve the response of photonic crystals by non‐array parameter control. Herein, novel thermal responsive photonic crystal (TRPC) with low angle dependent structural color is fabricated by introducing poly(ethylene glycol) into the structure of low angle dependent SnO₂ inverse opal. The response is achieved through the control of light path guided by phase transition and the significant volume change caused by the change of traditional array parameters can be effectively avoided. Meanwhile, the low angle dependent structural color of TRPC can effectively reduce the interference of observation angle change to response signal caused by external thermal stimulation. Patterned responsive photonic crystals with temperature gradient response are easily obtained by combining confinement self‐assembly and direct template method, and the patterns can be presented and hidden by the control of light path, showing great potential in anti‐counterfeiting and information encryption fields.     

基于胶体微球自组装光子晶体的结构生色

综述了近年来基于胶体微球自组装光子晶体结构生色的研究进展.先简要介绍了光子晶体和结构生色理论,然后阐述了以胶体微球为基本结构基元构筑光子晶体的自组装方法,探讨了光子晶体的结构色效果的表征方式和稳固性增强方法,最后总结了用胶体微球自组装法制备光子晶体的困难并展望了发展方向.     

Micro-indentation of metallic photonic crystals: experimental and numerical investigations

Photonic crystals (PCs) are synthetic materials that are used to control light propagation. PCs have a frequency bandgap where light is forbidden to propagate. This bandgap is strongly tied to the microstructure of the photonic crystal. Three-dimensional tungsten photonic crystal in a Lincoln-log microstructure has been suggested as a strong alternative filter in photovoltaic cells with significantly high power efficiency. PCs have also been suggested as sensors for submicron damage. Therefore, mechanical characterization of three-dimensional photonic crystals becomes of interest. Here we report on mechanical characterization of tungsten PC using means of micro-indentation. We also present a three-dimensional finite element simulation of the structural response of a Tungsten photonic crystal under micro-indentation load. Stresses developed in the PC can be used to quantify the level of damage in the crystal. We compare our simulation results with the experimental observations of a Vickers and Knoop micro-indentation experiments of tungsten PC. The FE models were proven able to simulate the mechanical response of the PC with a good accuracy. The calibrated FE models can be further used to realize the mechanical behavior of PC under different thermal and mechanical stresses when used as filters in photovoltaic cells or to simulate the effect of damage in PC sensors.     

非晶无序光子晶体结构色机理及其应用

结构色是一种由光学尺度的微纳结构与光相互作用形成干涉、衍射或散射而产生颜色的物理生色效应。与化学生色不同,结构色由于没有色素或者染料的参与,因此没有颜色褪色的现象,同时能够避免使用染料和色素带来的环境污染。目前结构色材料受到研究者和应用开发人员的广泛关注,大量的研究发现结构色可以来源于光子晶体与非晶光子晶体两种结构。光子晶体由规整的周期性结构组成,产生的颜色鲜艳却具有明显的角度依赖性。而非晶光子晶体,其"自身缺陷"导致的短程有序结构具备了各向同性的光子带隙、非虹彩效应、光局域化等特点,赋予了材料柔和亮丽不随角度变化的显色效果,可控的激光效应以及优良的发光效率,从而更能满足材料领域对光散射和光传输等方面的特殊需求。对非晶光子晶体的概念和结构,与可见光作用产生颜色的原理,以及制备非晶光子晶体的不同方法(平板刻蚀法、胶体颗粒自组装法、模板法、相分离法)做了详细的讨论,并对非晶光子晶体产生的结构色效应在光电器件、功能涂料和纺织材料等多个领域中的应用进行了展望。     

Enhanced light trapping in dye-sensitized solar cell by coupling to 1D photonic crystal and accounting for finite coherence length

Theoretical analysis of dye-sensitized solar cell integrated with photonic crystals based on coupled coherent and geometrical optics formalism has presented. The effect of structural parameters, such as thickness of layer, number of unit cells and light incident angle on the optical properties and photo-current magnification for the proposed photonic crystal based dye-sensitized solar cell have studied. The angular response of the cell in terms of light harvesting efficiency and cumulative photo-generation rate has also analysed. A strategy has presented to enhance the performance of the cell under oblique incidence. The effect of number of photonic crystal unit cells has also analysed in view of percentage enhancement in cumulative photo-generation rate. This work provides new insight into the design and tailoring of the photonic crystals to enhance the light harvesting efficiency in the solar cells.     

Properties of defect modes in geometrically chirped one-dimensional photonic crystals

The variation of the transmission coefficient with defect mode frequency in a geometrically chirped photonic crystal with central defect layer has been investigated theoretically using transfer matrix method and validated experimentally by fabricating and characterizing such photonic crystals. The defect mode frequency is extracted by modeling the defect layer as a Fabry-Perot resonant cavity with mirrors replaced by two geometrically chirped photonic crystals. It is shown that the structural asymmetry of the chirped photonic crystals with respect to the central defect layer affects the width of the photonic band gap and also induces coupling variation between the eigenmodes of the defect layer and those at the band edges of the constituent photonic crystals. This leads to variation in the defect mode transmittance across the photonic band gap and introduces notches at positions where the eigenmodes of the band edges have maximum transmission.     

Optical properties of three-dimensional P(St-MAA) photonic crystals on polyester fabrics

The three-dimensional (3D) photonic crystals with face-centered cubic (fcc) structure was fabricated on polyester fabrics, a kind of soft textile materials quite different from the conventional solid substrates, by gravitational sedimentation self-assembly of monodisperse P(St-MAA) colloidal microspheres. The optical properties of structural colors on polyester fabrics were investigated and the position of photonic band gap was characterized. The results showed that the color-tuning ways of the structural colors from photonic crystals were in accordance with Bragg’s law and could be modulated by the size of P(St-MAA) colloidal microspheres and the viewing angles. The L¹a¹b¹ values of the structural colors generated from the assembled polyester fabrics were in agreement with their reflectance spectra. The photonic band gap position of photonic crystals on polyester fabrics could be consistently confirmed by reflectance and transmittance spectra.     

Responsive Block Copolymer Photonic Microspheres

Responsive photonic crystals (PCs) have attracted much attention due to their broad applications in the field of chemical and physical sensing through varying optical properties when exposed to external stimuli. In particular, assembly of block copolymers (BCPs) has proven to be a robust platform for constructing PCs in the form of films or bulk. Here, the generation of BCPs photonic microspheres is presented with 3D periodical concentric lamellar structures through confined self‐assembly. The structural color of the spherical PCs can be tuned by selective swelling of one block, yielding large change of optical property through varying both layer thickness and refraction index of the domains. The as‐formed spherical PCs demonstrate large reflection wavelength shift (≈400–700 nm) under organic solvent permeation and pH adjustment. Spherical shape and structural symmetry endow the formed spherical PCs with rotation independence and monochrome, which is potentially useful in the fields of displays, sensing, and diagnostics.     

Enhancement of Faraday rotation in 3D/Bi:YIG/1D photonic heterostructures

We suggest a new design of magnetophotonic crystals. Microcavity-type magnetic photonic heterostructures exhibiting enhanced magneto-optical Faraday rotation have been fabricated. Such a heterostructure comprises an opal film (3D photonic crystals), a bismuth substituted iron garnet (Bi:YIG) spacer film acting as the defect layer, and a dielectric multilayer (1D photonic crystal). Localized mode was shown to exist in the photonic band gap as a result of resonant interference in heterostructures. The observed enhancement of Faraday rotation was more than three times as compared with that of the Bi:YIG constituent. We have also found that the heterostructures exhibit an unusual polarization-dependent response.