Facile Preparation of Functional Side-Chain/Supramolecular Polymeric Materials Toward Optoelectronic Applications

• Main Authors: Huang, Cheng-Wei, 黃政偉
• Other Authors: Zhu, Chao-Yuan
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/t42b48

博士 === 國立交通大學 === 應用化學系碩博士班 === 104 === In the recent past, living/controlled polymerization techniques have enabled the preparation of a large variety of distinct well defined co(polymer) architectures. To accelerate the research progress of novel polymers, it would be highly desirable to design a general polymer backbone with variable side-chain functionalities in order to tune the properties of the resulting (co)polymers. In the last decade, the use of supramolecular chemistry towards the synthesis of side-chain functionalized polymers has developed from a curiosity to a mature area of polymer science. Furthermore, it has to be demonstrated that polymers or complexes functionalized using non-covalent methodologies indeed possess advantages superior than their covalent counterparts. ‘Rapid optimization’ of these advanced materials and establishment of the methodology are actively pursued in a broad range of research fields. This thesis involves the design principles, syntheses, and methodologies of various functional side-chain/supramolecular polymeric materials via post-functionalization methods. Properties enhancement and potential applications are presented in both solid state and solution state: (1) Stimuli-Responsive Supramolecular Materials: Photo-Tunable Properties and Molecular Recognition Behavior A successfully introduction of multiple hydrogen bonding unit diaminopyridine (DAP) into a conventional polymer polystyrene (PS) utilizing nitroxide-mediated polymerization and CuAAC “click” technique have been proposed in this study. Complexation of this PVB-DAP polymer and thymine-functionalized azobenzene (Azo-T) through directional complementary triple hydrogen bonding interaction has led to a special photoresponsive behavior. A reversible trans-cis isomerization process can be observed upon UV light illumination and thus resulted in a change of surface properties. During isomerization, a hydrophobic-to-hydrophilic surface of supramolecular thin film according to water contact angle (WCA) measurements can be achieved with several repeated cycles. Furthermore, it was found that PVB-DAP/Azo-T supramolecular complex film have ability to form surface-relief grating from the interference pattern of polarized green light (532 nm) laser. The “recordability” and “rewritability” of these supramolecular complexes provides a unique strategy to perform stimuli-responsive materials for optical storage application. (2) Functional Supramolecular Polypeptides Involving π-π Stacking and Strong Hydrogen Bonding Interactions: A Conformation Study Toward Carbon Nanotubes (CNTs) Dispersion Novel supramolecular polypeptides were prepared through facile syntheses including ring opening polymerization (ROP) and "click" reaction. Supramolecular polypeptides PPLG-DAPs have been proven to enhance the α-helical secondary structures of PPLGs. An obvious increase of thermal properties and thermal responsivity has been provided by dynamic physical-crosslinking network of DAP-DAP self-assembly interaction. On the other hand, molecular recognition process has been carried out between DAP and thymine base pairs to form the peptide/pyrene supramolecular complex. TEM results suggest the supramolecular complex PPLG-DAP/Py-T can be used as an efficient carbon nanotube (CNT) dispersant in both polar and non-polar media via the combination of secondary interactions including multiple hydrogen bonding and π-π interaction. PPLG-DAP/Py-T/MWCNT composite with high Tg value thus enable the development of bioinspired carbon nanostructures and lead the way toward biomedical applications. (3) A Solvent-Resistant Azide-Based Hole Injection/Transporting Conjugated Polymer for Fluorescent and Phosphorescent Light-Emitting Diodes Side-chain functionalized conjugated polymer PTCAz has been synthesized for a precursor polymer through Suzuki-coupling method. The readily photo-crosslinkable unit and sufficient hole transporting ability made PTCAz a suitable material to fabricate hole injection/transporting layer (HITL) of solution-processed OLEDs. With the excellent solvent-resistance and remarkable electrochemical stability, PTCAz have offered an extra option to solve the interfacial mixing problem which generally decrease the efficiency of solution-processed OLEDs. As a result, the Alq3-based trilayer fluorescent device reached a maximum brightness of 52971 cd/m2, maximum luminance efficiency (LE) and power efficiency (ηE) are both higher than those of a corresponding device based on commercial PEDOT:PSS. In addition, a solution-processed phosphorescent OLED device incorporating X-PTCAzide also exhibited good performance (external quantum efficiency: 7.93%; LE: 29.6 cd/A; ηE: 14.3 lm/W; maximum brightness: 34,484 cd/m2). The efficient and simple photo-crosslinking without adding initiator could make PTCAzide a promising next-generation HITM for the development of highly efficient and inexpensive OLEDs. (4) Water-Soluble Fluorescent Nanoparticle Fabrication Based on Supramolecular Amphiphiles via Heterocomplementary Multiple Hydrogen Bonding Interactions Water-dispersible luminescent polymer dots with absence of ionic groups and simple preparation process are desired for their versatile applications especially in biological imaging. In this study, we proposed a facile strategy to fabricate Water-dispersible polymer dots through bio-inspired non-covalent molecular recognition process. The side-chain type supramolecular conjugated polymers, PC-T and PTC-T, were obtained from a brief modification of previously reported azide-functionalized polymers. Such hydrogen-bonded materials demonstrated distinct luminescent properties in protic and aprotic solvents while exhibited improved thermal properties and stabilities and more importantly, provided an extra pairing ability to other complementary base units. Supramolecular micelle can be therefore prepared from conjugated polymers and complementary hydrophilic polymer PEG-A. The resulting PC-T/PEG-A and PTC-T/PEG-A micelles exhibited at the scale of hundred nanometers and were able to act as “polymer dots” for in vitro experiments. The prescence of PEG shells created biomimetic surfaces that sustained the biocompatibilty for practical usage. Our attempt indicated the supramolecular system involved specific nucleus bases recognition may be a reliable process to apply hydrophobic polymers into modern biological analysis.