Manipulating The Aggregated Structure Of Conjugated Polymers Based On Non-covalent Bond Interactions And Their Applications

Conjugated polymers(CPs)are promising alternatives for the fabrication of organic optoelectronic devices and stretchable electronics.Manipulating the aggregation structure of CPs is an effective strategy for optimizing their overall properties.Introducing multiple synergistic non-covalent bond interactions provides a feasible method for accurately controling the selfassembly behavior and aggregation structure of CPs.In this dissertation,we focused on manipulating the aggregation structures of CPs and their composites,including conjugated polymers/carbon nanotubes(CPs/CNTs)nanocomposites,amphiphilic conjugated polymer,and doped conjugated polymers,based on non-covalent bond interactions.In the first part,the self-assembly structures of the conjugated polymer poly(9,9-dioctylfluorene)/single-walled carbon nanotube(PFO/SWCNTs)composites in solution were studied.It was found that SWCNTs could be straightened by PFO chains with both α-and β-conformations in different solvents.UV-vis and PL spectra confirmed that PFO chains could interact with SWCNTs,but PFO chains with β-conformation had a stronger interaction with SWCNTs,because the more coplanar β-conformers could be more closely attached to the surface of SWCNTs.Owing to the torsion between the adjacent structural units of PFO,SWCNTs were helically wrapped by the adsorbed PFO chains,and then PFO formed a rigid shell structure on the surface of SWCNTs.As a result,the rigidity of the PFO/SWCNTs composite was enhanced and straightened morphology was formed.The self-assembly of amphiphilic conjugated block copolymers in an aqueous environment is simultaneously affected by hydrophobic interaction and π-π interaction.In the third chapter,the interfacial self-assembly behavior of an amphiphilic conjugated block copolymer,poly(3-hexylthiophene)-b-poly(acrylic acid)(P3HT-b-PAA),at the oil-water interface was explored,and novel large-sized 2D nanotapes of P3HT-b-PAA were prepared.Meanwhile,the morphologies of P3HT-b-PAA assemblies at the oil-water interface could be regulated by type of oil solvent,water subphase p H,etc.It was found that the P3 HT segments adopted a more planar conformation and backbone of P3 HT stood vertically at the oil-water interface under suitable conditions,which facilitated the π-π interaction and alkyl side chain packing,and thus formation of nanotapes.A bi-layered model of nanotapes was proposed,which consisted of once-folded P3 HT layer and amorphous PAA layer.Blending CPs with insulating elastomers is a simple and economic method to acquire elastic semiconducting films.Introducing interactions between CPs and elastomers is beneficial for enhancing electrical and mechanical properties of the system.In this thesis,the stretchable semiconducting films were fabricated by blending poly(3-dodecylthiophene)(P3DDT)with a random copolymer poly(n-butyl acrylate)-co-poly(2-acrylamido-2-methylpropane sulfonic acid)(PnBA-co-PAMPS).It was found that P3 DDT could be doped by the sulfonic acid pendant groups of PnBA-co-PAMPS,leading to the formation of free carriers.Meanwhile,there existed electrostatic interaction between P3 DDT and sulfonic acid dopants.A fibril-like network structure of P3 DDT with an evenly spatial distribution in the PnBA-co-PAMPS matrix was formed,which provided continuous charge transport pathways.Therefore,the composite films exhibited higher hole mobility comparing to neat P3 DDT films.In addition,the composite films possessed good mechanical properties due to the diffused interface between P3 DDT and PnBAco-PAMPS.Designing block copolymers/CPs blend with an ordered microphase separated nanostructure is valuable in both basic theory and practical application for CPs-based composites.In the last part,the microphase separation behavior of poly(methyl methacrylate)-b-poly(oligo(ethylene glycol)methyl ether methacrylate)(PMMA-b-POEGMA)/sulfosuccinic acid(SSA)/P3 DDT blends was studied.It was ovserved that PMMA-b-POEGMA/SSA/P3 DDT blends could form lamellar phase separation structure,and the long period of lamellae could be adjusted by changing the amount of P3 DDT addition.In the blends,SSA could not only interact with OEGMA block via hydrogen bond but also interact with P3 DDT chains through dopinginduced electrostatic interaction.Therefore,SSA acts as an adhesive of OEGMA block and P3 DDT,allowing the P3 DDT chains to enter the phase domain of the OEGMA block.Besides,when the self-assembly process of blends was dominated by the π-π interaction,P3 DDT would form crystalline structure,which hindered the formation of microphase-separated structure.