Yangyang Zhu,Fei Gao,Jiang Zhong,Liang Shen,Yangju Lin
The utilization of bio-based precursors to prepare materials is highly desirable for the consideration of sustainable energy and materials. Vitrimers have received considerable attention because of their high mechanical performance that is comparable to conventional thermosets and advantageous reprocessability that allows to be recycled. However, most vitrimers are prepared from petroleum-based raw materials, and only a few examples employ bio-based raw materials, of which most utilize transesterification dynamic chemistry that often requires external catalyst that may leach or decompose during reprocessing. Herein, we report a catalyst-free vinylogous urethane vitrimer derived from renewable castor oil and DL-limonene. Prepared vitrimer shows excellent reprocessability and shape memory properties. We also envisaged that the strategy of preparing bio-based vitrimers reported here can be generalized to other bio-based raw materials that are rich in double bonds.
Amadori compounds, produced during Maillard reaction , are considered as precursors of flavor compounds . On the basis of Amadori compounds, herein two Amadori analogues, di- O -isopropylidene-2,3:4,5- β - D -fructopyranosyl alanine ester (A-ARP) and di- O -isopropylidene-2,3:4,5- β - D -fructopyranosyl proline ester (P-ARP), were chemically synthesized and their possibility as flavor precursors was evaluated by thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). TG-DTG analyses indicated that the samples were stable at room temperature , and the largest mass-loss rates ( T p ) were at 208 and 278 °C, respectively. Upon thermal pyrolysis, the major flavor substances were butan-2-one, ethyl propionate , furfural , and dl -limonene for A-ARP, while 2,5-dimethylfuran, heptan-2-one, acetophenone , and 1 H -pyrrole for P-ARP. The flavor profiles are different from that of corresponding Amadori compounds, and are influenced by pyrolytic temperatures. These results provide one method to regulate the species and amounts of the degraded flavor products. Finally, the possible mechanisms of the pyrolytic processes are proposed.
危险品化学品经营许可证（带存储）