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A cholesterol-functionalized poly(3-alkylesterfuran) (P3CHOLEF) was synthesized in three synthetic steps from 2-bromo-3-furoic acid. The polymer is synthesized by Suzuki-Miyaura cross-coupling polymerization using an N-heterocyclic carbene palladium catalyst. P3(CHOL)EF adopts a helical conformation, and the rigid side chain ensures the polymer remains folded in various solvents. This behavior is unique when compared to a similar polymer where the cholesterol group is replaced with S-3-octanol. When P3(CHOL)EF was dissolved in n-octane at room temperature and circularly polarized luminescence behavior was studied, a dissymmetry factor of 0.05 was recorded for the polymer.
The optimum processing conditions for PEDOT:PSS and PEDOT:PSS/Tween 80 cast films were determined in terms of sheet resistivity and film quality. The sheet resistivity of the films was found to decrease by up 85% following annealing at 140 °C. Further analysis showed this reduction to be created by both moisture removal and structural rearrangement. The presence of Tween 80 significantly altered the thermal stability of PEDOT:PSS films highlighting the importance of reoptimizing processing conditions for each additive used.
Double-cyclopolymerization of trifunctional heptaisobutyl-substituted corner-opening typed cage silsesquioxane produced soluble polymers by applying the precision polymerization technique to avoid cross-linking reaction during the polymerization. Cast films of the resulting double cyclic polymers showed excellent optical transparent and good thermal properties as well as stable hydrophobic surfaces.
We develop aldehyde-functionalized conjugated microporous polymer (CMPs) via Pd-catalyzed direct arylation polymerization strategy. The method avoids the pre-fucntionalization and reduces the number of synthetic steps. The polymers exhibit strong visible light absorption (red edge of λabs = ∼605 nm) and solid-state fluorescence (λem = 620 nm; ϕf = ∼5%). The pendant aldehyde functional group in the polymer enables selective fluorescent chemosensing of aliphatic and aromatic amines by enhancing the fluorescence of aliphatic amines and performing fluorescence quenching for aromatic amines.
The maintenance of stem cells multipotency and control of the differentiation direction are important for these applications in tissue engineering. We explored whether the multipotency of adipose derived stem cells (AdSCs) is maintained when they are removed from injectable polymer (IP) hydrogels with various degrees of cross-linking and induced to differentiate into osteoblasts and adipocytes. We confirmed that AdSCs cultured in IP hydrogels maintained an undifferentiated state. However, when cultured in an IP hydrogel, their multipotency was reduced.
The effect of different types of maleic anhydride-modified polypropylene on interfacial shear strength for carbon fiber-reinforced polypropylene composites: The effect of three types of maleic anhydride-modified polypropylenes (MAPP) on the interfacial shear strength (IFSS) of PP and carbon fiber (CF) were investigated. The localization of MAPP at the interface enabled sufficient chemical interaction regardless of MA content of MAPP, and the differences of MA content had little IFSS dependences. When the chemical interaction is sufficient at the interface, the IFSS values were attributed to the crystallinity at the interphase, which depends on the natures such as crystallinity of MAPP added.
Tricoordinate boron embedded conjugated polymers, so-called p−π* conjugated polymers, have been studied as optoelectronic and sensor materials. p−π* Conjugated polymers usually possess bulky aryl groups that kinetically stabilize the boron centers, and the bulky aryl substituents prohibit intermolecular interactions in the solid state. In this work, we synthesized new p−π* conjugated polymers based on a thiophene-fused thiaborin unit. The thiaborin-based p−π* conjugated polymers exhibited great red shifts in the absorption spectra measured in film state relative to those measured in solution, suggesting strong intermolecular interactions.
Fused expanded pyridinium cation (FEP) was introduced as a side chain of the polymer by click reaction. The obtained polymer offered membranes with good flexibility and showed excellent anion conductivity of 123.4 mS cm–1 at 80 °C under 80% relative humidity, although ion-exchange capacity of the polymer was quite low (0.77). Remarkable conductivity of the membranes is likely due to the weak interaction between FEP cation and OH–, which increases the ion mobility and concentration of OH–.
Stretchable mechanoelectric generators (MEGs) using ‘π-electrets’ composed of π-conjugated polymers modified with bulky, yet flexible alkyl side chains were fabricated. Facile control of the elastic modulus by blending two miscible alkylated π-conjugated polymers enables the laminated films in a MEG to have high stretching of up to 300%. The fabricated MEGs showed good conformability when applied to a soft object that underwent deformation.
The acidolysis, hydroxypropylation and esterification could influence the DSC curve of TG. Among them, the esterification obviously reduced the initial temperature, peak temperature and conclusion temperature.
We performed cationic ring-opening polycondensation of a galactose-based cyclic sulfite monomer to give (1 → 2)-galactan. Treatment of the cyclic sulfite with 10-(+)-camphorsulfonic acid (CSA) in the presence of water initiated ring-opening polycondensation to give benzylated (1 → 2)-galactan. The MALDI-TOF mass spectrum of the obtained polymer showed a simple pattern with even intervals, indicating the formation of benzylated (1 → 2)-galactan with OH termini. When we used 4-penten-1-ol as the alcohol initiator for cationic polycondensation, we obtained a pentenoyl group-terminated polymer and/or cyclic oligosaccharides. The mechanism for the polycondensation reaction was determine through systematic investigations of the polymerization and DOSY spectral measurements of the polymer. The present method may be useful with graft polymerizations designed to give oligogalactan-containing glycosides in one pot.
Water-insoluble poly(methacrylic acid) (poly(MAAc)) sponges with nanolayered structures were fabricated via thermal cross-linking with poly(vinyl alcohol) (PVA). The cross-linked sponges contained up to 75 wt% poly(MAAc) when the molecular weight of PVA and the cross-linking time were adjusted appropriately. After immersion in a NaClO·5H2O aqueous solution, all poly(MAAc)/PVA_50 wt% sponges with different PVA molecular weights were completely dissolved. Multilayer films of poly(MAAc)/PVA with different physicochemical properties were also fabricated. Among potential applications, these sponges can be used as adsorption materials for low molecular weight compounds and heavy metal ions.
Transition metal-free aldol condensation was applied to synthesize n-type conjugated polyelectrolyte (CPE), PIIGBDV-N. The quaternary ammonium groups with Br- ions on the side chain enabled in situ n-doping during polymerization, which resulted in strong polaron absorption in the near infrared region and increased conductivity of the obtained CPE. PIIGBDV-N exhibited good electron transport capability and can be utilized as thickness-insensitive electron transporting layer in high-performance organic solar cell devices.
Fused π−conjugated molecules have been utilized as key components in organic semiconductors due to their high charge-transport characteristics. In this study, we designed and synthesized a novel fused π−conjugated molecule composed of electron-donating benzodithiophene and electron-accepting naphthobisthiadiazole units and investigated its photo/electrochemical properties and semiconducting characteristics. The fused donor-acceptor-donor (DAD) molecule showed typical p-type characteristics with a hole mobility of 1.1 × 10−3 cm2 V−1 s−1. We also achieved the synthesis of a D-A type copolymer containing the fused DAD structure as an electron donor unit.
Ternary phase diagrams of the solvent/donor/acceptor system were studied to discuss the relationship between the photovoltaic properties of polymer solar cells and the phase-separated structures. The downshifted intersection points between the solvent drying pathway and binodal lines suggest the smaller domain sizes, and hence the higher exciton diffusion efficiency. The appropriate acceptor volume fraction close to the percolation threshold in mixed-phase shows high charge collection efficiency due to an effective charge transport and a suppressed bimolecular recombination.
By integrating the strongly electron-deficient building blocks cyano-substituted benzochalcogenadiazole and diketopyrrolopyrrole, two A-A polymers were constructed and exhibited decent solubilities, low-lying LUMOs, and ultra-narrow bandgaps, thus leading to a predominant n-type transporting characteristics. When n-type doped with N-DMBI-H, the A-A polymers delivered an n-type performance with a power factor of 9.22 μW m−1 K−2. The design strategy is highly informative for further developing n-type organic thermoelectric materials.
A better understanding of the carrier formation process for semiconducting polymers, especially in thin films, is essential for designing and constructing highly-functionalized polymeric optoelectronic devices. We herein examined effects of the crystalline structure and thermal molecular motion on photo-carrier formation for melt-crystalized thin films of monodisperse poly(3-hexylthiophene) (P3HT) with various molecular weights (MWs), which were prepared from polydisperse sample by preparative chromatography.
C–H/C–I direct arylation reactions for monomer synthesis and C–H/C–Br direct arylation polycondensation were investigated for the short-step synthesis of promising medium-bandgap polymers (PBDB-T) for OPV applications. Polycondensation and end-capping reactions using direct arylation have been established, enabling the synthesis of polymers without Br termini. The OPV performance of the synthesized polymer was lower than that of the benchmark polymer synthesized using the conventional method, despite having similar molecular weights. Possible factors for low OPV performance and future challenges include structural defects, impurities, and large molecular weight distribution.
