In our study, a polytetrafluoroethylene (PTFE) open-tubular enzyme-immobilized microreactor has been successfully prepared using dopamine polymerization and multi-layer deposition. The polydopamine layer was utilized as a primer layer in the microchannel to provide PTFE surface reactable groups, and polyethylenimine and Candida antarctica lipase B were alternatively adsorbed on the PTFE surface by the layer-by-layer method. The lipase loading kept increasing as the number of layers increased and reached a plateau at the 8th layer. The formation of multilayers and increase of enzyme loading were described and explained by the water contact angle measurement, Fourier transform infrared spectroscopy (FI-IR), and X-ray photoelectron spectroscopy, while the morphological characteristics were observed using Atomic Force Microscopy (AFM) and field emission scanning electron microscopy (FE-SEM). Preparation of a wax ester using the microreactor had much better production efficiency (35 minutes to reach 95% yield) than that using traditional reactors (over 4 hours to complete the reaction). Very excellent stability can be achieved by the microreactor, which could be used for 144 hours with the residual activity remaining at 83% of the initial activity.
Synthesized oleic acid-based wax esters (e.g., cetyl oleate), which can replace spermaceti oil or jojoba oil, have been widely used in the cosmetic, pharmaceutical and other industries. In this work, 4-dodecylbenzenesulfonic acid (DBSA) has been successfully used as an efficient catalyst to synthesize oleic acid-based wax esters through esterification at 40 °C under solvent-free conditions. A 93.6% conversion rate of cetyl alcohol was obtained under optimal conditions: 10 mol% DBSA, a molar ratio of 1.3:1 oleic acid to alcohol, a reaction temperature 40 °C and a reaction time of 4 h. The effect of water content on esterification was investigated, and it was found that the inhibitory effect of water decreased significantly with increasing temperature. Moreover, DBSA-catalyzed esterification could be applied in the production of various oleic acid-based wax esters and excellent conversion (>90%) to esters was obtained under such mild conditions. DBSA-catalyzed low-temperature esterification is an efficient method for the production of liquid wax esters.Keywords:liquid wax esters;4-dodecylbenzenesulfonic acid;esterification;oleic acid;high-oleic sunflower seed oil
Houchao Jing,Jinyang Feng,Jianping Shi,Lin He,Peipei Guo,Shuang Guan,Hai Fu,Yuhui Ao
Hydrogels that exhibit properties such as ultra-elongation, self-recovery, and self-healing have applications in sensors and many other fields. With these properties and applications in mind, we hypothesised that we could develop a strain-sensing hydrogel based on acrylic acid , stearyl methacrylate , cationic guar gum , and hexadecyl trimethyl ammonium bromide, without any covalent crosslinker. The hydrogels are instead held together by physical, non-covalent interactions such as ionic interactions, hydrogen bonding , and the hydrophobic effect , as suggested by spectroscopy and swelling experiments. The hydrogels exhibit many useful properties, such as: excellent stretching—up to 4267%—and almost complete reversion to their original state at a large strain of 500%, even after 20 successive cycles; temperature-dependent self-healing and self-recovery; and strain-sensitive conductivity that is attributable to the directional migration of ions. Because of these outstanding features, such as notch-insensitivity and the ability to withstand knotting under high strain, our hydrogels will be useful as flexible sensors.
危险品化学品经营许可证（带存储）