C60-Pyrene : 由尺寸不相稱的奈米區塊組成不定型之奈米海綿

Abstract

雙親性分子 (Amphiphilic molecules) 一般泛指兼具親水與疏水片段的分子，這類型的分子自組裝行為取決於其親、疏水片段的相分離傾向、分子量、溶劑與環境溫度等因素。形狀雙親巨分子 (giant shape amphiphiles) 是Prof. Stephen Z. D. Cheng在2014年所提出的概念，這類型分子由尺寸接近 1nm、形狀相異的分子奈米粒子 (molecular nanoparticle) 所構成，形狀相異的組成單元在形狀雙親巨分子組裝時傾向相分離，因而有序的交替排列結構。以共軛單元如：C60, 紫質 (porphyrin, por), triphenyl amine (TPA) 所形成的形狀雙親巨分子由於同時具有p型與n型的半導體特性，且能形成p/n分離的電洞/電子通道，故在有機光電領域中受到重視。然而，以往的形狀雙親物中p型:n型組成單元的尺寸或截面積往往十分接近，而組成單元的尺寸不相襯性如何影響形狀雙親物的自組裝結構與光電元件表現仍為一有待深入研究的課題。 故在本研究中，使用富勒烯 (C60) 作為n型電子受體 (acceptor, A)、pyrene作為p型電子予體 (donor, D) 合成出一系列形狀雙親巨分子。這系列分子將可用於研究尺寸不相稱的固態結構與共結晶現象和接鏈的親疏水性質，對形狀雙親巨分子自組裝行為的影響。

Giant shape amphiphiles are giant molecules made with molecular nanoparticles (MNP) of distinct shapes. The self-assembly behaviors of giant shape amphiphiles are influenced by not only secondary interactions, but also the packing constraints of the shape of each individual MNP. Because MNPs with different shapes have the tendency to phase separate into separated but continuous domains in the supramolecular assembles, bicontinuous channels or alternating layers of the constituent MNPs were observed in the self-assembled structures of Giant shape amphiphiles. For example. C60-porphyrin, C60-triphenyl amine shape amphiphiles form bicontinuous P/N channels, which deliver p type and n type semiconductor properties simultaneously. That’s why the giant shape amphiphiles hold potential in the optoelectric applications. In this study, self-assembly structures, and OFET characteristics of four C60-py shape amphiphiles were studied. The incommensurate sizes of C60 and pyrene and strong physical interaction between them hinder the C60-py shape amphiphiles from packing into ordered structures and forming separated C60/py channels. The C60/py shape amphiphiles are thus amorphous materials. Interestingly, upon correct amount of naphthalene diimide (NDI) guest is added, the pyrene unit of the shape amphiphile strongly interacts with NDI, and pack into 2D layers that contain ordered packing of pyrene/NDI charge transfer complexes. Simultaneously, the C60 unit of the shape amphiphile assemble into another 2D C60 layers next to the pyrene/NDI layer. In other words, the blend of C60-py shape amphiphile and the NDI guest co-assemble into a lamellar structure that contain alternatively arranged pyrene/NDI layers and C60 layers. DSC and XRD results show that adding ~ 2 eq. of the guest NDI allows the amorphous C60-py to completely transform into the supramolecular lamellaes. The incommensurate sizes of the C60 and pyrene therefore makes the C60-py shape amphiphiles an amorphous nanosponge that captures n-type guest molecules to co-assemble into supramolecular lamellar.