Abstract
In order to develop a novel controlled-release material, we previously attempted to impregnate poly(L-lactide) (poly(L-LA)), poly(L-LA-ran-CL) (CL: e-caprolactone) or poly(L-LA-ran-TEMC) (TEMC: tetramethylene carbonate) with low boiling point, organic useful compounds using supercritical carbon dioxide (scCO2) as the solvent. In this work, the factors influencing impregnation of poly (L-LA) random copolymers with useful compounds were investigated under scCO2 using the copolymers previously used. The influence of temperature, pressure, and time on the impregnation contents of the useful compounds on the copolymers was evaluated. The polymer used, which is a base of this material, was poly(L-LA-ran-CL), poly(L-LA-ran-TEMC), or poly(L-LA-ran-DXO) (DXO: 1,5-dioxepan-2-one). Statistical random copolymers of L-LA with CL, TEMC, or DXO were synthesized using Sn(oct)2 as a catalyst at 150°C for 24 h without solvent. Preparation of the controlled-release materials was carried out using essential bark oil from Thujopsis dolabrata var. hondae and synthetic L-LA random copolymers as a base material under scCO2. The impregnation experiment, which investigated the influence of pressure, was conducted in the range of 10 to 20 MPa. The influence of temperature on impregnation was carried out at 40°C to 100°C. Impregnation time was varied from 1 to 5 h. The pressure of essential oil impregnated into poly(L-LA) random copolymers was the highest at 14 MPa. In the influence of temperature on impregnation, the amount of essential oil increased with increasing temperature.
Highlights
Prevention of the reproduction and extermination of food poisoning bacteria, inhibition of molds that grow on walls, furniture, and inside buildings, such as houses, museums, etc. and extermination of insect pests and animals on farms or parks is a serious social problem
We previously reported on a study of the impregnation of poly(L-LA-ran-lactone), poly(L-LA-ran-cyclic carbonate), and poly(L-LA-ran-cyclic ester-ether) with d-limonene, hinokitiol, trans-2-hexenal, and α-pinene using supercritical carbon dioxide [20]-[22]
Essential bark oil from Thujopsis dolabrata var. hondae was the compound used for impregnation
Summary
Prevention of the reproduction and extermination of food poisoning bacteria, inhibition of molds that grow on walls, furniture, and inside buildings, such as houses, museums, etc. and extermination of insect pests and animals on farms or parks is a serious social problem. Structural lumber rots away internally, and eroded wooden structures might collapse if an earthquake occurs Remedies for these problems are chemical control, physical prevention of growth, extermination, biotic control, etc. In order to solve the above problems, the method of taking efficiently into the polymer material of low boiling points which does not use an organic solvent and selection of the polymer which has the highly efficient release ability replaced with porosity resin are required. In how to take in the polymer, as to suppress volatilization of the low boiling points and the lower of the physical properties of the polymer by heat which is a problem of the mulling method, it decided to apply the processing method using a supercritical fluid (SCF).
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