偶氮苯液晶聚合物的研究进展

偶氮苯类化合物由于具有独特的光致顺反异构特性,在液晶材料、光信息存储材料及非线性光学材料等许多领域都具有广泛的应用,因此近年来引起了研究者极大的关注.本文综述了近年来具有液晶性的偶氮苯类化合物的合成进展概况,对此类化合物进行了简单的分类,简要介绍和归纳了各类型化合物简单常用的制备方法,并对此类化合物的合成和研究方向作了展望.     

光致固液转变型偶氮苯聚合物的合成与光响应性能

偶氮苯聚合物由于其独特的光响应性能在光分子开关、信息存储等领域具有潜在的应用,但偶氮苯顺反异构化转变及光致固液转变的影响因素仍需要更深入的研究。文中设计并合成了4种偶氮苯聚合物,对比了偶氮苯相连的柔性链对其光响应性能的影响。研究发现,引入柔性链段使偶氮苯异构化时间从20 min降到100 s,同时含柔性链段的偶氮苯聚合物具有光致固液转变的能力,而不含柔性链段的偶氮苯聚合物不能发生光致固液转变。     

联萘基手性偶氮分子/液晶复合材料研究进展

基于对偶氮苯所具有的特殊的光致异构化反应机制的研究越来越深入,以偶氮苯衍生物为基础的光控材料引起广泛关注。介绍了联萘基手性偶氮分子的基本性质,综述了联萘基手性偶氮分子在胆甾相液晶反射薄膜、蓝相液晶、光诱导分子开关等方面的应用,并且对联萘基手性偶氮分子/液晶复合材料在光诱导分子开关、选择性反射等领域的发展前景进行了展望。     

含可加成反应偶氮苯聚合物的制备及表征

经过Diels-Alder反应等步骤制备了新型马来酰亚胺单体——甲基丙烯酸-4-(呋喃-马来酰亚胺乙基)酯(MMA-FMI),经过重氮、偶合等步骤制备了新型含呋喃环的偶氮苯单体——甲基丙烯酸-4-(4-呋喃-2-甲基-2-乙酸酯基偶氮)苯酯(MMA-FAzo),MMA-FMI、MMA-FAzo再与甲基丙烯酸-4-(4-甲氧基偶氮)苯酯(MMA-Azo-OCH_3)无规共聚得到含可加成反应偶氮苯聚合物(PAzo)。采用核磁共振氢谱、傅里叶变换红外光谱、凝胶渗透色谱对聚合物结构进行表征;使用紫外-可见分光光度计研究聚合物的顺反异构化行为,发现聚合物的光致顺反异构化速率常数为0.217 s~(-1),聚合物PAzo具有快速光响应性能;通过热失重分析仪研究聚合物的可加成特性;通过热可逆实验证明,交联的聚合物仍具有可回收与再加工性。     

1D-π-A型偶氮苯衍生物合成、表征及其光致变色性能

以4-氨基硝基苯为起始原料,通过溴代、重氮去氨基、硝基还原制备出重要中间体3,5-二溴苯胺,再以3,5-二溴苯胺和3-溴苯胺分别与苯酚衍生物进行重氮偶合反应,合成了10个D-π-A型偶氮苯衍生物,利用FT-IR、NMR、ESI-MS、元素分析和X-单晶衍射等表征方法,确定目标化合物结构,并通过UV-Vis光谱研究了系列目标化合物光致变色性能,测定其光致顺反异构速率常数。研究结果表明,目标化合物表现出显著光致变色性能,顺反异构转变速率常数数量级为10-2~10-3 s-1,异构转变速率快慢主要取决于化合物分子的取代基空间位阻大小。     

偶氮苯基小分子光控聚N-异丙基丙烯酰胺在离子液体中的自组装

偶氮苯基材料因其具有可逆的光致顺反异构特性,可调控聚合物的自组装行为而受到广泛关注。采用不同结构且广泛商业化的偶氮苯基小分子(偶氮苯(AZO)、对羟基偶氮苯(AZO-OH)、对氨基偶氮苯(AZO-NH₂)、二甲基黄[AZO-N(CH₃)2_])作为光分子开关,控制聚N-异丙基丙烯酰胺(PNIPAm)在1-乙基-3-甲基咪唑双(三氟甲基磺酰基)亚胺([C₂mim][NTf₂])离子液体中的自组装行为,探讨不同偶氮苯基末端基元对于PNIPAm自组装相行为的影响。结果表明,偶氮苯基小分子均能有效调控PNIPAm在[C₂mim][NTf₂]离子液体中的相变响应行为,但不同的末端基元对于PNIPAm的相变温度及相变区间影响甚微。结合原位变温红外谱图分析可知,紫外光照强化了PNIPAm与离子液体之间的相互作用,从而抑制了PNIPAm侧链间的相互聚集,这将促进紫外光照条件下“溶剂化”效应的发生,可获得更低的相变温度。     

点击化学法制备主链型偶氮苯聚合物及其表征

合成了含偶氮苯基团的双烯单体二丙烯酸己氧基偶氮苯基二酯(DAHAE)和二巯基单体二巯基丙酸丁二酯(DMPBE),经点击反应成功制备出主链型偶氮苯聚合物。利用核磁共振氢谱、凝胶渗透色谱等测试方法对聚合物进行了结构表征。热重分析法、差示扫描量热法测试表明聚合物具有优异的热稳定性和一定的结晶性能。通过偏光显微镜观察发现聚合物结晶形态为球晶。使用紫外-可见分光光度计研究聚合物的光致顺反异构化行为表明聚合物的光致反-顺异构化速率常数(ke)为0.10s-1,主链型偶氮苯聚合物具有快速光响应性能。     

乙基纤维素接枝偶氮苯聚合物的合成与研究

通过原子转移自由基聚合(ATRP)技术合成乙基纤维素接枝偶氮苯聚合物.以功能化乙基纤维素作为大分子引发剂,在CuBr/N,N,N′,N″,N″-五甲基二亚乙基三胺(PMDETA)催化体系下,以苯甲醚为溶剂,引发对甲氧基偶氮苯单体6-[4-(4-甲氧基苯基偶氮)酚氧基]己基甲基丙烯酸酯(MMAzo)的ATRP反应,构筑接枝共聚物.通过多种手段接枝共聚物结构、热行为与液晶性进行表征.接枝共聚物在紫外-可见光照射下发生可逆的顺反异构化反应,具有作为光学材料的潜力.     

新型含偶氮苯生色团聚合物的制备和性能

合成了含手性碳原子的新型偶氮苯生色团,通过酰氯化反应制备出含偶氮苯生色团的单体,将所合成的单体与丙烯酸酯类单体进行自由基共聚得到以偶氮苯生色团为侧基的高分子.利用1H NMR、FTIR、UV-Vis吸收光谱,对所合成的单体及聚合物进行了结构表征.研究了所制备的聚合物的全光开关效应.结果表明,在激发光的照射下,通过聚合物中偶氮苯基团的顺-反-顺异构循环在聚合物材料中可形成光致各向异性;在较低驱动光功率(28.1 mW)下这种聚合物具有良好的全光开关效应.     

含芳香偶氮高分子染料的光敏材料

本文研究了含对N,N-二甲氨基偶氮苯侧链的聚醚高分子梁料光敏材料的紫外光敏特性,并和小分子染料4N,N-二甲氮基偶氮苯(二甲基黄)光敏材料的性能进行了比较。结果表明,高分子染料光敏材料具有较好的光敏性。用x-射线光电子能谱研究光敏材料的表面组成表明,高分子染料光敏材料具有小分子染卦难以达到的贮存稳定性,克服了小分子染料从光敏层中迁移问题。     

Polarization-multiplexed optical memory with urethane-urea copolymers

We present a polarization-multiplexed optical memory with urethane-urea copolymers. The side chains of the urethane-urea copolymers induce cis-trans isomerization by illumination of blue or green light, and they align perpendicular to the linear polarization of the illuminated light, thus producing optical anisotropy. We found that the material showed selective anisotropy for the particular direction that was perpendicular to that of the recording beam polarization. By use of the anisotropic property three different data pages were multiplexed at the same spot of the medium. Erasure of the recorded bit data is also demonstrated.     

Recent research progress on optical limiting property of materials based on phthalocyanine, its derivatives, and carbon nanotubes

Carbon nanotubes and organic compounds with extensive delocalized π-electron system such as phthalocyanine and its derivatives are attracted much attention as potential optical limiting materials. In this article, the optical limiting properties of carbon nanotubes, phthalocyanine as well as its derivatives and modifying approaches to improve their optical limiting performance are reviewed. In addition, the optical limiting properties exhibited by the nanohybrids obtained from the combination between carbon nanotubes and phthalocyanine or its derivatives are also introduced.     

窄带隙聚吡咯甲烷衍生物的制备与光学性能

由于高分子发光材料具有柔韧性好、合成简单、可大面积制备和使用寿命长等优点,成为近年来显示和照明领域的研究热点。本文以N-甲基吡咯和苯甲醛类为单体,采用缩聚法制备了3种可溶性、窄带隙、分子主链为部分共轭的聚吡咯甲烷衍生物,并利用红外光谱、紫外-可见光谱、荧光光谱、X射线衍射谱和热失重分析等方法对其结构、光致发光性质和热稳定性能等进行了测试分析,比较了大分子链上苯环对位取代基对材料发光性能的影响。研究结果表明,3种衍生物的热稳定性较好且具有部分结晶性,其光学禁带宽度均小于1.6 eV,属于窄带隙聚合物;在355 nm左右激发光下,3种衍生物均会产生约420 nm的发射光,为蓝紫色发光材料,且大分子链上苯环的对位取代基对该类材料的发光行为基本没有影响;在循环伏安曲线中,3种衍生物均存在较为明显的氧化还原峰。聚吡咯甲烷衍生物在光电器件材料方面有着潜在的应用价值。     

A High‐Performance Optical Memory Array Based on Inhomogeneity of Organic Semiconductors

Organic optical memory devices keep attracting intensive interests for diverse optoelectronic applications including optical sensors and memories. Here, flexible nonvolatile optical memory devices are developed based on the bis[1]benzothieno[2,3‐d;2′,3′‐d′]naphtho[2,3‐b;6,7‐b′]dithiophene (BBTNDT) organic field‐effect transistors with charge trapping centers induced by the inhomogeneity (nanosprouts) of the organic thin film. The devices exhibit average mobility as high as 7.7 cm² V^?1 s^?1, photoresponsivity of 433 A W^?1, and long retention time for more than 6 h with a current ratio larger than 10⁶. Compared with the standard floating gate memory transistors, the BBTNDT devices can reduce the fabrication complexity, cost, and time. Based on the reasonable performance of the single device on a rigid substrate, the optical memory transistor is further scaled up to a 16 × 16 active matrix array on a flexible substrate with operating voltage less than 3 V, and it is used to map out 2D optical images. The findings reveal the potentials of utilizing [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) derivatives as organic semiconductors for high‐performance optical memory transistors with a facile structure. A detailed study on the charge trapping mechanism in the derivatives of BTBT materials is also provided, which is closely related to the nanosprouts formed inside the organic active layer.     

有机光存储材料及其进展

本文介绍了光盘写入及读出过程的基本原理，并就有机光存储材料性能，作用以及当前的发展趋势进行了讨论。     

末端为噻吩基团酯类化合物的合成、表征及液晶性能研究

以噻吩甲醛、对氨基苯甲酸、溴丙烷、对羟基苯甲酸为原料,经过醚化反应、希夫碱反应、DCC/DMAP酯化反应合成了噻吩衍生物液晶。化合物的结构由红外光谱、核磁共振氢谱进行了表征,噻吩衍生物的液晶性能用偏光显微镜进行了研究。结果表明:以噻吩为末端的化合物在升温和降温过程中均表现出很好的向列相液晶性能;特别是在降温过程中表现出较低的结晶点和更宽的液晶相温度范围。     

大尺寸ZnTe单晶生长技术的研究进展

介绍了以光电应用为背景的大尺寸ZnTe单晶生长技术的研究进展,综述了大尺寸ZnTe单晶不同生长技术的特点及其对单晶性能的影响,重点分析了为解决ZnTe生长过程中存在的蒸汽压过高的问题,通过控制提高Te的比例,实现低温低压生长,对比了不同生长方法的生长机理差异及其对单晶尺寸、缺陷和性能的影响,为寻求解决大尺寸单晶生长面临的问题提供了参考。     

All‐Optical Control of Shape

Photoresponsive liquid crystal elastomers (LCEs) are a unique class of anisotropic materials capable of undergoing large‐scale, macroscopic deformations when exposed to light. Here, surface‐aligned, azobenzene‐functionalized LCEs are prepared via a radical‐mediated, thiol‐acrylate chain transfer reaction. A long‐lived, macroscopic shape deformation is realized in an LCE composed with an o‐fluorinated azobenzene (oF‐azo) monomer. Under UV irradiation, the oF‐azo LCE exhibits a persistent shape deformation for >72 h. By contrasting the photomechanical response of the oF‐azo LCE to analogs prepared from classical and m‐fluorinated azobenzene derivatives, the origin of the persistent deformation is clearly attributed to the underlying influence of positional functionalization on the kinetics of cis→trans isomerization. Informed by these studies and enabled by the salient features of light‐induced deformations, oF‐azo LCEs are demonstrated to undergo all‐optical control of shape deformation and shape restoration.     

氢敏材料及氢气传感器的研究进展

对氢气进行快速、准确、原位测量,具有重要的学术意义和广阔的应用前景.氢气传感器发高品质氢敏材料的研制,氢敏材料的敏感响应性、重现性等决定着氢气传感器的工作性能.综述了近年来研究较多的半导体型、热电型、光学型、电化学型4类氢气传感器及相应氢敏材料的研究进展,并展望了氢敏材料及氢气传感器的发展方向.     

Optical switching of electric charge transfer pathways in porphyrin: a light-controlled nanoscale current router

We introduce a novel molecular junction based on a thiol-functionalized porphyrin derivative with two almost energetically degenerate equilibrium configurations. We show that each equilibrium structure defines a pathway of maximal electric charge transfer through the molecular junction and that these two conduction pathways are spatially orthogonal. We further demonstrate computationally how to switch between the two equilibrium structures of the compound by coherent light. The optical switching mechanism is presented in the relevant configuration subspace of the compound, and the corresponding potential and electric dipole surfaces are obtained by ab initio methods. The laser-induced isomerization takes place in two steps in tandem, while each step is induced by a two-photon process. The effect of metallic electrodes on the electromagnetic irradiation driving the optical switching is also investigated. Our study demonstrates the potential for using thiol-functionalized porphyrin derivatives for the development of a light-controlled nanoscale current router.