[Notes] A urethane acrylate derived from castor oil was synthesized using castor oil with 2 - acryloyloxyethyl isocyanate and obtained in high yield. Furthermore, the obtained urethane acrylate was subjected to a UV cure reaction with polybutadiene. The UV cured fi lm was characterized by thermal and mechanical measurements. The thermal stability of the obtained fi lm was measured by TGA, and 20% thermal weight loss temperature at 425 ° C was observed. The glass transition temperature of the product was ¹ 60 ° C as revealed by DMA. The Young ’ s modulus of the product was 2.00MPa, taken from the stress - strain curve.
We have conducted computer simulation to understand the feature of the grain coarsening of polymer microdomains. For this purpose, the phase field crystal model was utilized with the conserved potential field and perpendicularly oriented cylindrical microdomains were simulated, being evoluted from the disordered state. As a result, the power-law behavior was confirmed as the grain size is proportional to t(alpha), where t is the simulation time. The growth exponent alpha was further found to be dependent on the noise strength zeta in the simulation. Two different power-law behaviors were found for early and late stages for all of the results except for zero noise strength for which a single power-law behavior was observed over the entire time range. alpha increased from 0.16 to 0.33 (for the late stage) with increasing noise strength. Although the result (0.16 <= alpha <= 0.33) contradicts our previous experimental result (alpha = 0.45) obtained by atomic force microscopy and small-angle X-ray scattering [Polymer Journal, 2017, 49, 6551, simulated images are rigorously examined to understand the features of the grain coarsening. The following features are found. First of all, not only point defects but also line defects can exist in a grain. Both of them can trigger to create a new grain boundary or a small grain. Such formation of small grains was just transient so that they disappeared immediately. The reason why such transient grains are necessarily formed may be due to an instability in larger grains in the course of their growth. Such instability is caused by the localized energy due to a heavy distortion of the hexagonal lattice. As an example of the slow process of grain coarsening, it is suggested that slow movement of the grain boundaries can be driven by the change of the position of individual cylinders from the original grain to a neighboring grain. Furthermore, heavily curved grain boundaries are forced to be immediately straightened due to the high energy of the bent grain boundaries. Thus, we can recognize that the grain coarsening is driven by a dynamic movement and exchange of grain boundaries, as we have speculated in our previous publication.
An unsymmetric diblock copolymer b-Q57A97 of (ar-vinylbenzyl)trimethylammonium chloride (Q) and N,N-dimethylvinylbenzylamine (A), synthesized by reversible addition-fragmentation chain transfer radical polymerization, and its molecular assemblies were characterized by static and dynamic light scattering and steady state fluorescence using N-phenyl-1-naphthylamine (PNA) as a probe. Scanning electron microscopy observations indicated that b-Q57A97 formed a unique fern leaf-like morphology in the presence of NaCl.
A urethane acrylate derived from castor oil was synthesized using castor oil with 2-acryloyloxyethyl isocyanate and obtained in high yield. Furthermore, the obtained urethane acrylate was subjected to a UV cure reaction with polybutadiene. The UV cured film was characterized by thermal and mechanical measurements. The thermal stability of the obtained film was measured by TGA, and 20% thermal weight loss temperature at 425 degrees C was observed. The glass transition temperature of the product was -60 degrees C as revealed by DMA. The Young's modulus of the product was 2.00 MPa, taken from the stress-strain curve.
Interpenetrating polymer network (IPN) gels have been synthesized by combination of networks formed by thiol-ene reaction of multifunctional compounds with bifunctional compounds (1st network) and ring opening polymerization of poly(ethylene glycol) diglycidylether (PEGDE) (2nd network). The 1st network was formed by thiol-ene click reaction of a multi-functional vinyl siloxane, (1,3,5,7-tetramethylcyclotetrasiloxane, TVMCTS) and an alkyl dithiol, (1,10-decane dithiol, DDT) in toluene. The mechanical properties of the IPN gels were investigated by compression tests. The IPN gels showed a higher breaking stress and breaking point than the single network gel. The 1st network has been also synthesized by the thiol-ene reaction of multi-functional thiol compounds and poly(ethylene glycol) diacrylate in some organic solvents (toluene, tetrahydrofuran). These IPN gels also showed higher breaking stress and breaking point in comparison with the corresponding single network gels. The IPN gels with PTMB showed higher Young's modulus due to the physical entanglement between the 1st and 2nd networks. The reaction system of caster oil-hexamethylene diisocyanate (HDI)/epoxized soybean oil (ESO) was also usable to synthesize IPN gels. The 1st and 2nd networks were formed by the addition reaction of caster oil and HDI, and ring opening polymerization of ESO, respectively. The composition ratio and formation order of the 1st and 2nd network affected the mechanical properties of the resulting IPN gels.
As a completely biomass-based wood plastic composite material, a cellulose derivative (cellulose propionate, CP) composite material with added Erianthus fibers (EF) was developed. The biomass fiber EF was added to the cellulose derivative, and the rigidity of the cellulose derivative was greatly improved (tensile modulus improved by 149%). Although the strength decreased as the fiber content increased, it was revealed that it was possible to improve the tensile strength by preparing a cellulose derivative having an increased amount of residual hydroxyl groups and using it as a matrix component of a composite material (tensile strength is improved by 131%). Furthermore, it was confirmed that the thermal characteristics of this composite material are retained. Therefore, CP/Erianthus fiber achieved balanced thermal properties and better mechanical properties than petroleum derived PP/MAPP composites.
The aim of this study is to evaluate the adhesive properties of UV-curing liquid (ink) on a non-porous surface. We examined how the adhesive strength was affected by the ink characteristics, as different type mono-functional monomers were used in the ink composition. The flexibility of the cured film structure seems to be crucial for improving adhesive strength, because a flexible structure can relax the internal strain that exist between the substrate and the cured film surface. It seem that when we use methacrylate type mono-functional monomers (CHMA, HEMA) in the ink composition, the two monomers play an important role in the ink system in order to reduce the crosslinking density of the cured film. Also, we understood that acrylate type mono-functional monomers (CHA, HBA) were effective to increase adhesive strength because of their low surface tension and less shrinkage, although the two inks containing each monomers formed relatively higher crosslinking density of cured films than the methacrylate type ones.
Electron Spin Resonance (ESR) spectroscopic studies directed at clarifying the fundamentals of radical polymerizations have been conducted. Optimization of measurement conditions allows direct detection of radicals in polymerization reactions and well-resolved ESR spectra can be obtained. The spectra provide information not only on the structure, properties, and concentration of radicals but also information on the initiating and propagating (oligomeric and polymeric) radicals in radical polymerizations. A combination of ESR and atom transfer radical polymerization (ATRP) provided significant new information on the properties of radicals in radical polymerization, e.g. dependency of chain length, dynamics, and reactivity (hydrogen transfer) of propagating radicals. Up to now, it has been extremely difficult, even impossible, to obtain such information from ESR spectra during conventional radical polymerization. To overcome this difficulty radical precursors of oligo- and poly(meth)acrylates were prepared by ATRP and purified. Model radicals, with given chain lengths were generated by the reaction of well defined radical precursors with an organotin compound and were observed by ESR spectroscopy. tert-Butyl methacrylate (tBMA) radicals with various chain lengths showed clear chain length dependent ESR spectra. Especially, the ESR spectra of the dimeric model propagating radical were examined in detail at various temperatures.
Surface reliefs (SR) in crystalline diacetylene (DA) films have been investigated. Blue polydiacetylene (PDA) was locally formed by irradiation of ultraviolet light through a photomask to DA crystalline films. Exposing these films to heat or organic solvent vapor led to surface relief formation by transfer of the DA in the unexposed area to the exposed area accompanied by the PDA color transition from blue to red. A highly photosensitive SR formation was attained and stable SR in the crystalline DA films were obtained.
Carbon nanotubes (CNT) are a fibrous carbon material with very high aspect ratio due to having nano-size diameter and lengths of more than 1 mu m. Therefore, CNT reinforced rubber shows high electrical conductivity, thermal conductivity and strength, even though the added CNT is a small fraction only. In this research, characteristics of CNT/rubber composites exposed to high-pressure hydrogen gas are assessed. As a result, it is confirmed that both, the equilibrium hydrogen content and the volume expansion, when exposed to high-pressure hydrogen gas, are excellent after uniformly dispersing SWCNT in the rubber, better than for other CNTs. Because of these pressure hydrogen characteristics, the CNT/rubber composites in this research are expected to be useful as highly durable seal materials in a high-pressure hydrogen environment.
The influence of added divinylbenzene (DVB) cross-linked particles, having a diameter of 3 mu m and 30 mu m, on the lamellar microphase-separated structure of styrene-1,4-rich-isoprene (SI) diblock copolymer is investigated. The DVB particles readily sedimented in toluene solution of SI due to low dispersibility, therefore the particles were localized in the lower part of the solvent-cast films. The lamellar structure, formed in the process, exhibited preferential orientation along the direction parallel to the film surface, and the domain spacing along the perpendicular direction was lower than in the parallel direction. The degree of preferential lamellar orientation was lowered by adding the DVB particles, leading to an increment in the domain spacing. Furthermore, the DVB particles with larger diameter gave lower domain spacing, though they produced a lower degree of lamellar orientation.
A method for the precision synthesis of hetero-telechelic poly(ethylene glycol) (PEG)s with a carboxyl group at the alpha-terminus was studied. Hydroxypivalic acid (HPA) that contains both a hydroxyl group and a carboxyl group, was used as the starting compound. Anionic ring opening polymerization of ethylene oxide (EO) proceeded quantitatively by dropping a solution of HPA into potassium naphthalate THE solution, which induces highly dispersible initiators. In addition, it is indicated that macromonomers with a polymerizable group at the omega-terminus of PEG were synthesized quantitatively. And furthermore, a synthetic method to produce branched hetero PEGs with one carboxyl group at the alpha-terminus and two PEG chains were established by using a similar method. These quantitative synthetic methods of hetero PEGs possessing a carboxyl group at the alpha-terminus are promising for the creation of highly functionalized materials in the future.
ESR spectroscopic studies directed at clarifying the fundamentals of radical polymerizations have been conducted. Optimization of measurement conditions allows direct detection of radicals in polymerization reactions and well-resolved ESR spectra can be obtained. The spectra provide information not only on the structure, properties, and concentration of radicals but also information on the initiating and propagating (oligomeric and polymeric) radicals during radical polymerization. A combination of ESR and atom transfer radical polymerization (ATRP) provided significant new information on the properties of radicals in radical polymerizations, e.g. dependency of chain length, dynamics, and reactivity (hydrogen transfer) of propagating radicals. For acrylates, each ESR spectrum of dimeric, trimeric, tetrameric, and pentameric tert-butyl acrylate (tBA) model radicals observed at various temperatures provided clear experimental evidence of the 1,5-hydrogen shift. In this research work, ESR spectra observed during radical polymerization of tBA above 30 degrees C, could be completely explained as being due to mid-chain radicals, using several experiments and a special simulation program.
A syndiotactic-rich polystyrene (sPS) in a mixed solvent of toluene and chloroform converted to a thermoreversible gel from its semi-dilute solution. According to measurements of gel-melting temperatures, toluene behaved as a relatively poor solvent for sPS, while chloroform was a relatively good solvent. The critical gelation concentration C*, i.e., the minimum concentration for gel formation became higher with increasing the volume fraction of chloroform X-chloro. In order to characterize the sPS physical gel formed in a mixed solvent, the junction length zeta and rho sequence were estimated as a function of the volume fraction X-chloro using the thermodynamic theory derived by Tanaka and Stockmayer. The theory suggested that the junction size S (zeta x rho) was ca. 320-450 for sPS/toluene gel, 150-200 for sPS/chloroform gel, and the junction size S decreased with increasing X-chloro. In other words, the junction size S became larger when a gel was formed in a poor solvent. FT-IR spectral data suggest that sPS chain adopted the T(2)G(2) conformation in the mixed solvents of toluene and chloroform, and then gelation occurred. FE-SEM images show a fibrillar morphology of the sPS gel.
Five kinds of protic ionic liquids (PILs) were synthesized by the neutralization reaction of amidine and carboxylic acid (acetic acid, propionic acid, or butyric acid), and the esterification reaction of cellulose, using acetic anhydride, was carried out in PILs. The obtained cellulose derivatives were soluble in DMSO. In the H-1 NMR spectra of the cellulose derivatives, not only the chemical shift of acetyl group derived from acetic anhydride, but also the chemical shift, based on the anion of PILs, were observed. The degree of substitution (DS) of the produced cellulose derivatives varied depending on the structure of PILs. The obtained cellulose derivatives showed a thermal decomposition temperature above 270 degrees C and a glass transition temperature below 170 degrees C.
We synthesized polyoxamides (PX) using various diamines and diphenyl-oxalate (DPO) and investigated their molecular weight, copolymer composition, thermal properties, mechanical properties, swelling behavior for electrolytes of lithium ion batteries (LIB) and adhesive properties with electrodes of LIB. We established a new method to synthesize PX with high molecular weight by using N-methylpyrrolidone as a synthesis solvent, setting temperature to 200 degrees C and devising the order of charging diamine and DPO. All PXs synthesized in this study were crystalline polymers, harder than polyvinylidene-di-fluoride (PVdF) and had smaller elongation than PVdF. Both, the saturated swelling ratios of PX for electrolytes of LIB and the changes in mechanical properties due to swelling were small. We found in this study that the adhesive properties of PX copolymers composed of 1,3-bisaminomethylcyclohexane and hexamethylenediamine on both cathode and anode were good, but they were inferior to that of PVdF.
In this study, aligned-type piezoelectric rubbers with a thickness of 5 mm in which piezoelectric particles were aligned in the direction parallel to the thickness by an electric field were fabricated in order to decrease the spring constant. Numerical simulations of ferroelectric particle alignment by an electric field were also carried out. Our method in which moldings were inverted before applying an electric field led to longer particle alignments for piezoelectric rubbers with 10-20 Vol% of particles, which led to an enhancement of their piezoelectric property. The method was modified to control particle position before applying an electric field and the piezoelectric property of piezoelectric rubber with 30 Vol% of particles was enhanced. Furthermore, the particle alignment was affected by particle position before applying an electric field in numerical simulation. Spring constants of thicker piezoelectric rubbers were compared to previously prepared thinner ones.
In this work, we investigated the direct halogenation of growing species in living anionic polymerization of hydrocarbon monomers for subsequent mechanistic transformation and post-polymerization reactions. The direct halogenation of propagating living anionic species of isoprene (Ip) was examined with CCl4 in THF/methylcyclohexane at -78 degrees C to form a carbon-halogen terminal. The mechanistic transformation from living anionic into radical polymerization was then investigated using the anionically-prepared poly(Ip) (PIp) bearing a chloride terminal as the macroinitiator for the living radical polymerization with the RuCp*Cl(PPh3)/Et3N initiating system in toluene at 80 degrees C, which resulted in the formation of block copolymers of PIp with various radically-polymerized segments. Furthermore, the terminal halogen of the anionically-prepared PIp was also converted into an azide group by S(N)2 reaction, which could be employed for the click reaction with alkyne-terminated poly(ethylene oxide) by a Cu catalyst to form an amphiphilic block copolymer.
