Impregnation of poly(L-lactide-ran-δ-valerolactone) with essential bark oil using supercritical carbon dioxide

Abstract

This work studied the incorporation of essential bark oil from Thujopsis dolabrata var. hondae, which is known to repel various insects, in poly(L-lactide-ran-δ-valerolactone) [poly(L-LA-ran-VL)] using supercritical carbon dioxide (scCO2). The poly(L-LA-ran-VL) was synthesized by first purifying the monomers by azeotropic distillation with benzene, followed by polymerization with Sn(oct)2 using the same equipment, representing an efficient one-pot process. The copolymerization of L-LA with VL using this technique at a feed ratio of 90/10 mol/mol gave poly(L-LA-ran-VL) (91/9) with a molecular weight of 6.48 × 104 g/mol and a high yield of 74.9%. Products with molecular weights over 5.0 × 104 g/mol were obtained at L-LA feed proportions of 70 to 90%. Impregnation trials were conducted between 40 and 120 °C at 14 MPa for 3 h. The oil content of a 73/27 specimen was found to increase significantly during processing at 100 or 120 °C. During enzymatic degradation with proteinase K, the 91/9 specimen showed the fastest degradation rate. Although the 71/29 sample was slowly hydrolyzed in a phosphate buffer at pH 7.0, the release of oil vapor from this material was slightly higher than that from the 91/9 specimen, and the vapor release rate continuously increased throughout the hydrolysis process.

Recent Developments in Lactone Monomers and Polymer Synthesis and Application

“…Copolymers of LA with lactones such as ε-caprolactone or δ-valerolactone can serve as carriers for nutrients in agriculture. Impregnation with, for example, repellents allows for a product that during biodegradation is characterized by a slow release of the ingredient, which positively affects the sustainability of agriculture and reduces its negative impact on the environment [49]. PCL, during the breakthrough into resorbable polymers in the 1970s and 1980s, was mainly used in the field of biomaterials and drug delivery systems due to its mechanical properties, biodegradability and compatibility with other polymers.…”

Supercritical Fluid Extraction from Zataria multiflora Boiss and Impregnation of Bioactive Compounds in PLA for the Development of Materials with Antibacterial Properties

“…The SC-CO 2 assisted impregnation process consists of three steps; (i) dissolution step, in which the pure substances or active components dissolve in the supercritical fluid, (ii) sorption step, at this stage the swelling of the polymer take place by the sorption of SC-CO 2 and the dissolved active substances, and (iii) depressurization step; at this stage, by a fast decrease of pressure (i.e., decrease of solvent power) inside the high-pressure vessel, the active substances that have less affinity to the polymer could precipitate in higher extent on the polymeric matrix increasing the impregnation yield. However, a very fast decompression may damage the polymeric structure [16][17][18][19][20]. Today, the SC-CO 2 assisted impregnation has replaced conventional techniques for encapsulating active nutraceutical compounds into food grade substances to protect them against degradation (functional foods) or to incorporate active substances into polymeric matrices for active food packaging applications [21][22][23].…”