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The crystalline phase of PVDF film prepared by spin-coating changes both of the polymer–solvent interaction and the evaporation rate. In the much solvent remained state, the crystalline phase changes in the order of α, γ and β phase with increasing the dipole moment of solvent. In the solvent-evaporated state, the crystalline phase of PVDF and solvent with higher dipole moment system changes in the order of β, γ and α phase with increasing the solvent evaporation rate, whereas the PVDF and solvent with lower dipole moment system forms into α phase regardless of the evaporation rate.
A green method for the synthesis of ‘artificial urushi’ has been developed using cardanol, a main ingredient of cashew nutshell liquid, as the monomer via a reaction mimicking that of natural urushi. A water-in-cardanol (w/o) emulsion was developed by identifying a novel emulsifier, and polymerization of the cardanol emulsion generated prepolymer films, leading to polycardanol (artificial urushi) after curing with mechanical properties that are approximate to those of natural urushi coatings.
Time evolution behavior is described for a transient network formed via hydrogen bonds in a random copolymer of vinyl acetate and vinyl alcohol. As the cross-link density depends on temperature, the storage modulus G′ of the system slowly evolves toward equilibrium at the experimental temperature, Ta, after changing the temperature from higher or lower than Ta. The ‘memory effect’ (the structure developed at a certain temperature is preserved after changing the temperature) found in the system is discussed in detail.
Self-healable gel was designed by end-crosslinking of controlled telechelic polymer carrying a trithiocarbonate group in the middle of the chain. The prepolymers, which were precisely synthesized by RAFT polymerization, were crosslinked with branched crosslinker using activated ester chemistry to produce the network with same molecular weight network chain between crosslinking points. The obtained gel showed UV-induced self-healing owing to the function of the trithiocarbonate groups.
The results of the X-ray diffraction suggest that the dπ-spacing distance for poly(diethylhexyloxy benzo dithiophene-dioctyloxy dithiophene dibenzophenazine (PBDTAFQ) (dπ=3.89Å) was smaller than poly(diethylhexyloxy benzo dithiophene-dioctyloxy dithiophene diphenyl Qu) (PBDTAQ) (dπ=4.36 Å) because of fused-phenyl ring derivative. As a result, PBDTAFQ displayed a higher absorbance at the UV–vis absorption spectra in the film state. And, as a consequence, PBDTAFQ showed an improved short current density (JSC) in organic photovoltaic cells. The PBDTAFQ:PC70BM blend devices that were fabricated exhibited a power conversion efficiency of 3.4%.
Titanium phosphonate (TiOPPh: [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(PhPO3)3]·thf) was synthesized. TiOPPh was mixed with poly(methyl methacrylate) (PMMA) or poly(vinyl alcohol) (PVA) to prepare organic–inorganic hybrid polymer films. The film using PMMA was formed by the interaction between organic and inorganic components. The temperatures of 10% weight loss of TiOPPh–PMMA were 30 °C higher than that of PMMA only. The film using PVA was formed by the alcohol exchange reaction between TiOPPh and PVA. The transparency of TiOPPh-PVA in the visible region was higher than that of PVA only.
Alkylated dinaphtho[2,3-b:2',3'-d]furan (DNF–V) derivatives are systematically investigated in view of the impact of the substitution position as well as length of alkyl side chains. For both alkylated DNF–VV and DNF–VW derivatives, the solubilities as well as phase-transition temperatures increase as the shorter alkyl chains are attached. Especially, alkylated DNF–VV simultaneously gain the high solubility over 1 wt% and highly stabilized crystal phase up to 199 °C. Furthermore, DNF–V derivatives exhibit deep-blue emission in solid state with the quantum efficiency ranging from 17 to 51%.
Regioisomeric introduction of barbituric acid and aliphatic tail units onto anthracene core resulted in distinctly different π–π stacking arrangements upon aggregation in nonpolar solvent, resulting in the formation of supramolecular polymers with either non-helical or helically twisted fibrous morphologies. The difference in the topology of these fibrous nanoaggregates is attributed to the conformational difference of anthracene chromophores with respect to the plane of hydrogen-bonded supermacrocycle.
To investigate the effect of the branching position of the alkyl side chain of semiconducting polymers, we synthesized two series of semiconducting polymers based on thienothiophene-2,5-dione (PTTD4Ts) and quinacridone (PQA2Ts). The polymer thin films exhibited small but clear differences in their optical absorption spectra and X-ray diffraction patterns, suggesting that the intermolecular interaction in the solid state varied as a function of the branching position. Although PTTD4Ts did not exhibit a clear correlation between the branching position and charge carrier mobility, the mobility of PQA2Ts gradually increased as the branching position moved away from the backbone.
The influence of the grafting ratio of PMMA on the shape memory effect was studied by synthesizing and characterizing fast recoverable polyurethane/montmorillonite–poly(methyl methacrylate) (PU/MMT–PMMA) composites. PMP3 with a grafting ratio=3 had the fastest recovery rate, 21.1° per second at 60 °C, whereas the recovery rates of PU and PU/MMT were 6.1 and 9.5° per second, respectively. All the samples recovered to the original shape in 3 s at 80 °C, while PMP3 displayed a much higher shape memory performance capacity than the other two specimens in 1 s.
The molecular orientation of polymer-stabilized nematic liquid crystals (PSLCs) doped with oligothiophene can be easily manipulated using irradiation with linearly polarized light above a threshold intensity. The photoresponsive behavior depended on the initial molecular orientation, as controlled by the surface treatment of PSLC cells. The threshold light intensity for molecular reorientation was successfully reduced by 30% by optimizing the silane coupler concentration because of the decrease in surface anchoring. Thus, weak surface anchoring leads to a reduced threshold light intensity for molecular reorientation.
A glycopolymer with different mannose incorporation ratios was synthesized via a reversible addition fragmentation chain transfer with acrylamide. The polymers were immobilized onto a gold substrate by the thiol terminate. The glycopolymer layer structures and the glycopolymer–protein interactions were analyzed using a surface plasmon resonance technique. The glycopolymers formed pancake-like structures under dry conditions and were swollen in water. The interaction between the glycopolymer and the protein was enhanced by the cluster effect of the mannose units.
A carboxylic acid-terminated dendrimer was synthesized via a Steglich esterification of a hyperbranched polyol precursor. Progressive neutralization of the carboxylic groups was carried out, yielding a series of ionic dendrimers. In the ionic clusters, the anion–cation electrostatic interactions induced by the neutralization process dramatically affected the chain mobility of the polymer chains and their order–disorder transition temperatures. The self-assembly of the ionic dendrimers from aqueous milieu into 2D tree morphologies is demonstrated, highlighting their potential use as a highly versatile template for multifunctional semiconductor applications.
Hydrophilic tetraethylene glycol moieties are incorporated into the electron-accepting block of a donor–acceptor block copolymer (BCP) to afford two novel amphiphilic materials based on the P3HT-b-PFTBT scaffold. These amphiphilic BCPs are designed to provide enhanced morphological control as organic photovoltaic active layer materials. The chemical disparity introduced by the hydrophilic side chains enabled the design of a purification system capable of isolating the BCP product, an advantage over previously reported systems.
A series of conducting copolymers including fluorene (F) and 3-hexylthiophene (3HT) were synthesized in chloroform by chemical oxidative polymerization with FeCl3, and the incorporation of fluorene and 3HT units into the resultant copolymer main chain was clarified. The quantum yield value of obtained copolymers determined by relative method increased by the amount of incorporated fluorene molecules in the resulting copolymer backbone. In addition, fluorene was demonstrated to play an important role in enhancing the thermal stability of the copolymers.
Alternating current bipolar electropolymerization of 3,4-ethylenedioxythiophene (EDOT) was performed in the presence of benzoquinone in tetrabutylammonium perchlorate/acetonitrile. The obtained poly(3,4-ethylenedioxythiophene) (PEDOT) was deposited at both ends of bipolar electrode (BPE) gold wires in a linear fiber form (φ=ca. 30 μm) owing to limited accessibility of the EDOT monomer to the active site of BPEs in a micro-space. The linear growth of the PEDOT microfibers was demonstrated to be useful for application in circuit wiring.
Polymeric materials can be directly converted into molecular recognition materials by applying alternative molecular imprinting. This is expected to produce adsorbents that can specifically adsorb cesium ions. To this end, a polymeric adsorbent was converted from polyacrylonitrile, adopting cesium chloride as a print molecule. As a result, Cs+-recognition sites were formed in the presence of CsCl during the adsorbent preparation process. The adsorbents obtained in the present study are expected to be useful as specific adsorbents for capturing the nuclear waste, Cs+.
The first oligo(3-methoxythiophene) films that naturally appeared gold-like and lustrous green color tones were prepared by the cyclic potential-sweep electropolymerization of 3-methoxythiophene. Control experiments and optical/structural analyses showed that the films consisted of the edge-on and face-on lamella structures of the oligomers, and that the former structure contributed to the development of gold-like luster. Also, it was suggested that the action of the cyclic potential sweep was to preferentially destroy the face-on lamella, highlight the effect of the edge-on lamella, and develop gold-like luster.
Significant progress in cylindrical microdomain orientation is reported for a polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene triblock copolymer (SEBS-16) as analyzed by two-dimensional small-angle X-ray scattering. To achieve this goal, the morphological transition from sphere to cylinder was utilized. By applying compressional flow to the SEBS-16 specimen undergoing a morphological transition at 210 °C, superior cylinder orientation was achieved compared with the results obtained by applying compressional flow to the SEBS-16 specimen containing the cylindrical phase.
Cubic silsesquioxanes (POSS) with various alkyl substituents were loaded onto commodity-conjugated polymers such as polyfluorene and poly(3-hexylthiophene-2,5-diyl) to investigate structure-property relationships between the substituents of POSS fillers and properties of the polymer films. It was found that the series of POSS fillers can be introduced into conjugated polymer films with high concentrations. Owing to high miscibility, it was demonstrated that POSS can work as a superior molecular filler for realizing homogeneous amorphous films with high thermal stability based on conjugated polymers.
