In this study, we focus on nanoencapsulating organic dyes that absorb the near-infrared region and using them as anti-counterfeiting inks. By nanoencapsulation, it has the ability to disperse in water, which is used as a dispersion medium for inkjet inks, for example, and enables stable dispersion. In addition, in order to maintain the transparency of the anti-counterfeiting ink, the particle size of the nanocapsule needs to be large enough to transmit visible light. In this study, nanocapsules were prepared using an in-liquid drying method and the control of particle size was examined. By adding 1.5 wt% or more of polyoxyethylene sorbitan monooleate (Tween80) to the organic phase, nanocapsules with an average particle diameter of about 100 nm could be obtained.

The reactivity and polymerization behavior of imidazole-initiated polymerization of mono-functional epoxy resins containing 1,4-butanediol type (BDO-Ep) and polytetrahydrofuran type (PTHF-Ep) side groups were examined with the aim of expanding their use to semiconductor package encapsulant applications. 2-Ethyl-4-methyl imidazole (2E4MZ) was chosen as an initiator. The copolymerizability of PTHF-Ep with glycidyl phenyl ether (GPE) was also examined. It was confirmed that ring-opening polymerization of the epoxy group occurred in BDO-EP and GPE by using 2E4MZ. In the case of the PTHF-Ep, although the ring opening reaction of the epoxy group occurred with time, no polymerization took place and no significant increase in molecular weight was observed. Considering the ratio of 2E4MZ to PTHF-Ep and the polymerization temperature, the amount of 2E4MZ was decreased from 10 to 2 phr and the reaction temperature was elevated to 150°C. Although the reaction rate was decreased by lowering the molar ratio of 2E4MZ, the ring opening reaction at 120°C and 150°C progressed with time, and the number-average molecular weight (Mn) slightly increased. When polymerization of PTHF-Ep was carried out at 150°C and 180°C for 12 h., a slight broadening of SEC chromatogram at the higher molecular weight was observed compared with the one obtained at 120°C for 12 h. In the copolymerization of PTHF-Ep and GPE, rapid consumption of GPE followed by slow consumption of PTHF-Ep was observed regardless of the polymerization temperature (120–180°C). In addition, the weight-average molecular weight (Mw) and molecular weight distribution (Mw/Mn) in the reactions at 120°C and 150°C for 120 min. were approximately 2,000 and 1.5, while at 180°C, Mw increased to approximately 7,000 and Mw/Mn to 4.8. These results suggest that PTHF-Ep may have partially polymerized.

In this study, mesoporous materials MCM-41 and SBA-15 were prepared by template extraction using supercritical carbon dioxide (CO₂). When using the supercritical CO₂ method, the extraction ratio of the template agent for MCM-41 reached 97.8%, and silica with a high specific surface area, high pore volume, and uniform pore size was obtained compared to the conventional calcination method. For SBA-15, the template extraction ratio using the supercritical CO₂ method was only 88%, but the supercritical CO₂ method was superior to the calcination method in maintaining the uniformity of the pore size distribution. Furthermore, the pressure dependence of the template agent extraction ratio in the supercritical CO₂ method was investigated, and it was found that the extraction ratio showed a maximum around 8 to 10 MPa, which could be interpreted in terms of the vapor–liquid equilibrium relationship between CO₂ and methanol. Based on the above results, it was suggested that the supercritical CO₂ method is an extremely effective method for maintaining the pore structure and producing high-performance mesoporous silicas (MCM-41 and SBA-15) compared to conventional methods.

In this paper, we aimed to improve the efficiency of optimization process for production of microcapsules with targeted diameter (100 µm to 200 µm) prepared by the simple coacervation method using Bayesian optimization (BO). The coacervation method have been widely used for microcapsule preparation. However, for production of microcapsules with desired properties, a large number of experimental parameters must be optimized. The optimization requires much time and cost. Therefore, we tried to optimize the parameter by BO to solve the issues. The parameters were temperature, concentration of polymer (gelatin) as a component of the capsule wall, amount of aqueous solution with dissolved polymer phase separation inducer (sodium sulfate), and dropping rate of aqueous solution of sodium sulfate. Training data obtained under seven different conditions showed that the percentage of microcapsules with the targeted diameter was 0 to 21±3%, but BO could improve that percentage to 34% only by 4 trials. Thus, BO was useful as an efficient parameter optimization method for the preparation of microcapsules prepared by a simple coacervation method with the targeted diameter.

All-biomass materials, fabricated through wet extrusion of wood powders with water-soluble cellulose derivatives and auxiliary agents, are emerging as a sustainable alternative to plastic products. However, challenges such as shrinkage, deformation, and surface hardening during drying persist. To address these issues, we applied a combined infrared-ventilation drying method to all-biomass wet-extruded molded products, leveraging the excellent heat transfer properties of infrared radiation and the efficient mass transfer of ventilation. By optimizing the drying conditions, specifically by adjusting the infrared radiation and ventilation parameters when the sample center temperature reached 363 K, we achieved a significant reduction in drying time up to 41% and energy consumption up to 38%, respectively. Furthermore, all-biomass materials dried using this method exhibited minimal surface deformation and shrinkage, and their chemical composition remained relatively unchanged, as confirmed by near-infrared spectroscopic image analysis.