研究目的
To investigate the impact of backbone fluorination in block copolymers on the thermal stability of optical and morphological properties, comparing them to homopolymer blends for potential use in organic photovoltaic devices.
研究成果
The fluorinated segments dominate the optoelectronic and thermal properties in both block copolymers and blends. Block copolymers show slightly frustrated crystallization but enhanced thermal stability of intramolecular order compared to blends, as evidenced by temperature-dependent Raman spectroscopy. This suggests potential for improved thermal stability in organic photovoltaic active layers, though optimization in processing is needed.
研究不足
The synthesis of block copolymers can be difficult to control, with discrepancies between feed and actual block ratios. Solubility issues limited GPC measurements for some polymers. Purification may not fully remove homopolymer impurities, affecting results. The study is limited to specific polythiophene systems and may not generalize to other materials. Temperature-dependent measurements were conducted under controlled conditions but may not fully replicate real-world operational environments.
1：Experimental Design and Method Selection:
The study synthesized partially fluorinated diblock polythiophene copolymers using Kumada catalyst transfer polymerization (KCTP) to control block lengths. Methods included synthesis, purification via Soxhlet extraction, and characterization using NMR, GPC, DSC, UV-visible absorption spectroscopy, PESA, and temperature-dependent Raman spectroscopy.
2：Sample Selection and Data Sources:
Samples included two block copolymers (P3OT-b-F-P3OT with 2:1 and 1:4 block ratios) and corresponding homopolymer blends, synthesized from monomers 2 and 4 as per previous work.
3：List of Experimental Equipment and Materials:
Equipment included Bruker AV-400 NMR spectrometer, Agilent Technologies 1200 series GPC, Shimadzu UV-1601 spectrometer, Riken Keiki AC-2 PESA spectrometer, TA DSC-Q20 instrument, Renishaw inVia Raman spectrometer with 785 nm laser, and Linkam THMS600 hot-cold cell. Materials included reagents from Aldrich and Acros, solvents like THF, methanol, acetone, hexane, chloroform, dichloromethane, 1,2,4-trichlorobenzene, and 1,1,2,2-tetrachloroethane-d
4：Experimental Procedures and Operational Workflow:
Polymers were synthesized via KCTP, purified by Soxhlet extraction with selective solvents, and characterized. Films were spin-cast or drop-cast from hot solutions for various measurements. Temperature-dependent studies involved annealing films on a hotplate under argon and in situ Raman spectroscopy with controlled heating and cooling.
5：Data Analysis Methods:
Data were analyzed using NMR integration for block ratios, GPC for molecular weights, DSC for thermal transitions, UV-visible spectroscopy for absorption profiles, PESA for ionization potentials, and Raman spectroscopy for vibrational modes and thermal stability, with normalization and baseline subtraction.
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