石墨烯表面接枝聚(3-己基噻吩)分子刷的制备与表征

结合高效率重氮盐加成和Kumada催化-转移缩聚反应(KCTP),聚3-己基噻吩(P3HT)被共价接枝在石墨烯(GN)表面,形成聚合物分子刷(P3HT-GN).通过重氮盐偶合反应,溴苯分子首先被共价连接在氧化还原方法制备的GN表面,由此锚固的Ni(PPh3)4随后引发3-己基噻吩的催化-转移聚合.原子力显微和热失重分析结果表明,接枝在GN表面的P3HT分子刷厚度约为5 nm,重量分数为20.1%.当假设P3HT以伸直链构象接枝在GN表面时,估计的接枝密度为每6.53 nm2含有1个P3HT链,链间平均距离为2.556 nm.P3HT-GNs的X射线衍射在扫描范围内没有GN层间衍射峰出现,表明接枝后的GN是很好剥离的.P3HT-GN的紫外-可见光谱在300～500 nm范围内显示有比纯P3HT更弱的吸收峰,表明P3HT与GN之间存在显著的相互作用,与X-射线光电子能谱中增大的氧化噻吩环含量的结果是一致的.P3HT与GN的强相互作用使得光诱导产生的荧光几乎完全被淬灭,量子产率仅为0.042%,相当于纯P3HT的1/80,显示了突出的电荷转移效率.

POLY(3-HEXYLTHIOPHENE) BRUSHES GROWN FROM GRAPHENE NANOSHEETS

Poly(3-hexylthiophene)(P3HT) was for covalently grafted on the graphene(GN) surface to form polymer brushes(P3HT-GN) via combining diazonium addition with Kumada catalysis-transfer polycondensation(KCTP).GNs was prepared according to the well-established oxidization-reduction method where the surfactant was used to prevent the reduced GNs from aggregation.The bromobenzene molecules were then grafted onto the GN surface through the diazonium addition at the presence of surfactant,which allowed immobilization of the initiator Ni(PPh3)4 on GNs and subsequent growth of P3HT following the KCTP mechanism.Atomic force microscopy and thermogravimetric analysis results indicate that the thickness and weight percentage of P3HT brushes grafted on GNs are 5 nm and 20.1 wt%,respectively.When assuming these P3HT chains were grafted on GNs in fully extended configurations,the grafting density was estimated to be one P3HT chain/6.53 nm2 with an average inter-chain distance of 2.556 nm.There is no visible characteristic X-ray diffraction peak in the scanning range of 3°~60°,indicating that these P3HT-grafted GNs are well exfoliated.UV-Vis spectra revealed that P3HT-GN had a weaker absorption peak than the pristine P3HT in the wavelength range of 300~500 nm,suggesting a significant interaction between P3HT and GN.This is consistent with the increased content of oxidized thiophene units observed in the X-ray photoelectron spectroscopy of P3HT-GN relative to that of the pristine P3HT.The strong interaction between P3HT and GN made the photo-induced fluorescence nearly quenched completely.The obtained quantum yield for P3HT-GN is 0.042%(only an eightieth of the pristine P3HT quantum yield),exhibiting an extraordinary charge transfer efficiency between P3HT and GN.This opens up a new pathway for developing novel,high-efficient graphene-based functional materials.