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To develop highly functional gel materials, the precision construction of the network structure is required. This focus review outlines the structural design of polymer gels by utilizing precision radical polymerization techniques with a focus on the authors’ recent research. In particular, the synthesis of homogeneous networks using precise radical polymerization and the control of the swelling characteristics by tuning the monomer sequence in the gel network chain are described.
This focus review describes that “elastic organic crystals of π-conjugated molecules”. The author developed the field of innovative materials for flexible optoelectronics. Intentional design of intramolecular interaction in π-system furnish the flexible crystals. These crystals show not only elastic bending flexibility and shape tunability but also functionality for mechanical sensors and flexible optical waveguide.
The development of organic semiconductors (OSCs) applicable to organic field-effect transistors is crucial to printed and flexible electronics. OSCs must meet several prerequisites: 1) high chemical stability, 2) charge carrier mobility exceeding 10 cm2/Vs, 3) appropriate solubility, and 4) high thermal durability. The author and collaborators developed state-of-the-art OSCs based on bent-shaped π-electron cores (π-cores) that satisfy the requirements for printed semiconductor devices. In this focused review, the chemistry and device engineering are introduced with respect to sulfur-bridged V-shaped and N-shaped π-cores among a series of bent-shaped π-cores.
We successfully controlled birefringence and its wavelength dispersion of cellulose esters by choosing different ester substitution groups and sites, controlling the orientation of the crystal, adding low-mass molecules, and forming microscale porous structures. The substitution of two ester groups could provide extraordinary wavelength dispersion of birefringence, which is important for wide-range retardation films. The low-mass additives enhance birefringence values due to the intermolecular orientation correlation with matrix cellulose esters. The anisotropic microporous structure produced by thermoinduced phase separation generates form birefringence, which improves the total birefringence of cellulose esters.
The dependence of the fracture surface energy on the stretching velocity for nanoporous polypropylene (PP) sheets was found to consists of static and dynamic components. These terms can be interpreted respectively as plastoelastic and viscoelastic components, as has been shown for soft polyethylene (PE) foams in a previous work. This simple physical interpretation suggests a universal mechanism for the fracture of porous polymer sheets, and could be useful for designing new tough polymers.
We fabricated the doubly crosslinked gel by stretching the gel during the gelation using tetra-PEG gels. In this gel, two networks having different reference states coexist with and balance each other, influencing Young’s modulus (E) and permanent set (λs). We tuned the time for the stretching imposition on the gels, which influences the 1st network fraction (g1/g0). λs increased with increasing the 1st network fraction, while E had a maximum value against g1/g0, which were explained by the balance between the strain energies of the first and second networks.
Salt concentration dependence of NaPSS polymacromonomer with 110 monomeric units on each side chain (unfilled circles) cannot be explained by the theory assuming the Debye–Hűckel (DH) potential under the ionic strength outside the brush (dotted line), but can be explained using the DH potential under the ionic strength inside the brush (dashed line) along with the interactions without ionic ones (dot-dashed line).
Oligomeric siloxanes bearing unconventional fluorescence units, i.e., oxygen, amino, and hydroxyl functionalities, show the intrinsic blue fluorescence that results from oxygen clusters, namely, the CTE mechanism. In addition, intermolecular hydrogen bonds are conducive to the aggregation of the molecular chains and the formation of oxygen clusters.
Solutions of PVA in DMSO exhibit higher viscosities and relaxation times compared to solutions of PVA in water and are expected to show higher fiber diameters on electrospinning. Contradictorily, the fiber diameters of electrospun fibers of PVA-DMSO system are lower than that of PVA-water system. This atypical behaviour arises due to pseudostructure formation in DMSO, thereby resulting in an increase in the viscosity and relaxation time but a drop in entanglements resulting in lower fiber diameters. Therefore, a direct correlation between entanglements per chain and fiber diameter was deduced.
We have synthesized a new nonfullerene electron acceptor, BP(DPPB)4, with a biphenyl core and four diketopyrrolopyrrole arms. After thermal annealing at 120 °C for 10 min, the device based on P3HT:BP(DPPB)4 (2:1) obtained a power conversion efficiency of 1.43% with a high-open-circuit voltage of 1.17 V.
The birefringent properties of poly(phosphonate)s and poly(thiophosphonate)s possessing various bisphenol structures were investigated. The CR values (orientational birefringence) of the poly(phosphonate)s and the poly(thiophosphonate)s range from −0.3 × 10−9 to + 1.3 × 10−9 Pa−1 and from −0.6 × 10−9 to + 0.8 × 10−9 Pa−1, respectively, which are lower than those of the corresponding bisphenol A-based polymers. The CD values (photoelastic birefringence), which range from + 4.0 × 10−11 to + 4.9 × 10−11 Pa−1, are also lower than those of the corresponding bisphenol A-based polymers.
The new epoxy resins containing degradable acetal linkages were synthesized and used as sizing agents for carbon fibers. Using the degradable sizing agent-applied carbon fibers, the carbon fiber-reinforced plastics (CFRPs) were prepared via laminating prepreg sheets and heating them under pressure. The mechanical properties of the obtained CFRPs were comparable with those of the conventional CFRPs. With the treatment of acidic conditions, the CFRPs with the degradable sizing agents on carbon fiber surface were decomposed and the carbon fibers could be recovered.
Single-walled carbon nanotubes (SWCNTs) wrapped by poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI) was used for a cathode material of lithium (Li)-oxygen (O2) rechargeable battery. Compared to the Li–O2 cell using nonwrapped SWCNTs, the cell using PyPBI-wrapped SWCNTs showed improved rechargeability during charge–discharge cycles. It was revealed that PyPBI layer facilitated the homogeneous deposition of the discharge products, resulting the smooth reaction during the cycles. The coordination of Li ion onto PyPBI surface might be the key mechanism to realize the homogeneous deposition.
When the radical polymerization inhibitor 1,4-naphthoquinone (NQ) acts on styrene, the radical capture reaction greatly contributes carbon atoms. In this study, the 1-phenethyl radical, which is a model for the growth radicals of polystyrene, was reacted with NQ using four radical sources, and we identified the reaction product. We confirmed that the same compound was formed upon addition of a small amount of NQ to heated styrene. The frontier orbital energy levels and reaction path energy diagrams were calculated, which provided numerical values to support our experimental results.
