Search

Carbon nanotube (CNT)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite fibers with the CNT content ranging from 10 to 50 wt% were prepared by a wet-spinning process using a common solvent/coagulation system for application to organic fiber-based thermoelectric generators. After post-treatments, such as immersion in hydrazine solutions and polyethyleneimine-infiltration, the thermoelectric properties of the CNT/PEDOT:PSS composite fibers were optimized, with p- and n-type power factors of 83.2 ± 6.4 and 113 ± 25 μW m −1  K −2 , respectively. The electrical power generation capability of an organic fiber-based thermoelectric generator assembled with the p- and n-type CNT/PEDOT:PSS composite fibers was confirmed. [ABSTRACT FROM AUTHOR]

This study explores the structure-property relationships in colorless polyimides (CPIs) synthesized from stereoisomeric (exo - and endo -form) alicyclic dianhydrides, combined with various diamines. The structural configurations of 5,5'-(1,4-phenylene)bis[hexahydro-(3aR,4R,5R,7S,7aS)-rel-4,7-Methanoisobenzofuran-1,3-dione] (BzDA- exo) and 5,5-(1,4-phenylene)bis(hexahydro-4,7-methanoisobenzofuran-1,3-dione) (BzDA- endo) were confirmed as exo - and endo -forms, respectively, through 1H NMR and 2D NOESY NMR analyses. Wide-angle X-ray scattering (WAXS) data revealed that stereoisomeric structures influence polymer chain packing in synthesized CPIs. The investigation extended to the chemical and physical structure-dependent properties such as physical, thermal and optical properties of the PIs. Notably, structure-dependent physical and thermal properties were evident, with a particularly strong structure-property relationship manifesting in the coloration and yellow index (Y.I.) of PIs. These systematic characterizations offer profound insights into the design and optimization of chemical and physical structures in CPIs, highlighting the versatility of stereoisomeric monomers for various applications. [Display omitted] • Systematic characterization of structure-property relationships in CPIs from stereoisomeric anhydrides with various diamines. • Significant effects of stereochemical configurations on the mechanical, thermal, and optical properties of colorless polyimides. • Effects of varying chain packing structures, due to different monomers, on mechanical and optical properties. [ABSTRACT FROM AUTHOR]

A catalyst system comprising Cp*TiCl 2 (OPhTz) (Cp* = C 5 Me 5 , OPhTz = tetrazole-mono- ortho -substituted phenoxy anion), i Bu 3 Al, and [Ph 3 C][B(C 6 F 5) 4 ] is employed in the vinyl-addition copolymerization of norbornene (NB) and 1-octene (OT) to understand the catalytic effects of the N -donor tetrazole substituent. Copolymerization is accompanied by significant β-hydride elimination, producing poly(norbornene- co -1-octene) (P(NB- co -OT)) with low yield and molecular weight. Although the incorporation of OT into the copolymer is less than expected, competitive incorporation of the two monomers is observed. Increasing the mole fraction of OT in the feed reduces both the yield and molecular weight of the copolymer. Spectroscopic analysis reveals that the catalyst system yields P(NB- co -OT)s that are terminated prior to complete monomer conversion, along with non-isolated cooligomers and OT-derived isomers. The cationic titanium(IV) center stabilized by the N -donor tetrazole substituent facilitates the highly regioselective 2,1-insertion of OT. This slows subsequent monomer insertion, thereby promoting β-hydride elimination. [Display omitted] • A non-bridged half-titanocene complex containing a tetrazole-phenoxy ligand was developed. • This complex was used with cocatalysts to catalyze copolymerization of norbornene and 1-octene. • The catalyst system enabled competitive incorporation of norbornene and 1-octene to the copolymer. • Regioselective 2,1-insertion of 1-octene facilitated β-hydride elimination. • The β-hydride elimination resulted in low yields and low molecular weights of copolymers. [ABSTRACT FROM AUTHOR]