Graphene Functionalized with Azo Polymer Brushes: Surface‐Initiated Polymerization and Photoresponsive Properties
Graphene Functionalized with Azo Polymer Brushes: Surface‐Initiated Polymerization and Photoresponsive Properties
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DOI：
10.1002/adma.201003653
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发表时间：
2011-03
影响因子：
29.4
通讯作者：
Dongrui Wang;G. Ye;Xiao-lin Wang;Xiaogong Wang
中科院分区：
文献类型：
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作者：
Dongrui Wang;G. Ye;Xiao-lin Wang;Xiaogong Wang
石墨烯作为一种真正的二维纳米材料首次被成功制备以来，以其独特的结构和优异的性能引起了人们的极大关注。[ 1，2 ]石墨烯是功能器件中众多应用的最佳候选者之一，如气体传感器，[ 3 ]光电子器件，[ 4 ]和场效应晶体管。[ 5 ]在石墨烯基面或边缘上进行化学改性的通用方法为纳米材料提供了额外的新功能。[ 6 ]如果使用化学改性的艾德石墨烯作为填料，则可以在非常低的填料含量下显著增强聚合物基纳米复合材料的电、热和机械性能。[ 7，8 ]最近，单层石墨烯的光学性质引起了相当大的研究兴趣。[ 9-13 ]虽然石墨烯的反射和透射已经被深入研究，但关于石墨烯对纳米复合材料光学性质的影响知之甚少。石墨烯具有二维（2D）有序结构，具有独特的电子能带结构，其中导带在布里渊区中的两个点处接触价带。[ 9，10 ] 2D结构中的电子表现得像无质量的狄拉克费米子，并且可以显示出与电磁场的独特相互作用。石墨烯具有由精细结构常数定义的视觉透明性，在可见光范围内具有高透明度（97.7%）和折射率（2.6-3）。[ 9-13 ]鉴于这些独特的特性，光与纳米复合薄膜之间的相互作用可能是一个具有重大科学意义的课题，其结果可用于改进传统聚合物和其他有机材料的光学应用。本文报道了偶氮聚合物刷接枝单层石墨烯的制备及其在偶氮分子玻璃薄膜上光诱导表面浮雕光栅（SRG）衍射效率（DE）的显著提高。本工作中使用的功能化石墨烯（G-PCN）和偶氮分子玻璃（TrAz-CN）的化学结构如图1所示。偶氮苯及其衍生物具有光诱导的可逆顺反异构化反应。[ 14 ]含偶氮苯或其衍生物的聚合物（简称偶氮聚合物）
Since it was fi rst successfully prepared as a true two-dimensional nanomaterial, graphene has attracted tremendous attention for its unique structure and outstanding properties. [ 1 , 2 ] Graphene is one of the best candidates for numerous applications in functional devices such as gas sensors, [ 3 ] photovoltaics, [ 4 ] and fi eld-effect transistors. [ 5 ] The versatile approach of chemical modifi cation on the graphene basal planes or edges affords nanomaterials with additional novel functions. [ 6 ] If chemically modifi ed graphene is used as a fi ller, the electrical, thermal, and mechanical properties of polymer-based nanocomposites can be dramatically enhanced at a very low fi ller content. [ 7 , 8 ] Recently, the optical properties of single-layered graphene have aroused considerable research interest. [ 9–13 ] Although the refl ection and transmission of graphene have been intensively studied, little is known about the effect of graphene on the optical properties of the nanocomposites. Graphene has a two-dimensional (2D) ordered structure with unique electronic band structure, in which the conduction band touches the valence band at two points in the Brillouin zone. [ 9 , 10 ] Electrons in 2D structures behave like massless Dirac fermions and could show unique interactions with electromagnetic fi elds. Graphene possesses visual transparency, defi ned by the fi ne structure constant, with high transparency (97.7%) and refractive index (2.6–3) in the visible light range. [ 9–13 ] In view of these unique characteristics, the interaction between light and the nanocomposite fi lms could be a subject with great scientifi c signifi cance, and the results could be used to improve upon conventional polymers and other organic materials for optical applications. In this Communication, we report the preparation of singlelayered graphene grafted with azo polymer brushes and its interesting use to signifi cantly enhance the diffraction effi ciency (DE) of photoinduced surface-relief gratings (SRGs) on azo molecular glass fi lms. The chemical structures of the functionalized graphene (G-PCN) and azo molecular glass (TrAz-CN) used in this work are shown in Figure 1 . Azobenzene and its derivatives are well-known for their reversible trans–cis isomerization induced by light irradiation. [ 14 ] Polymers containing azobenzene or its derivatives (azo polymers for short)