Poly(propylene carbonate) (PPC) is a new biodegradable aliphatic polycarbonate with poor thermal stability and mechanical properties which shows difficulty in forming film by melt-extrusion technology. Through the addition of polystyrene (PS), the melt-extrusion film processability, thermal stability and mechanical properties of PPC was improved largely. PPC/PS films were prepared in the the melt-extrusion process successfully. DSC data showed that there was some degree of miscibility between PPC and PS. SEM showed good dispersion of PS particles into PPC matrix. Improved mechanical properties and thermal stability of PPC/PS blends were attributed to homogeneous dispersing and stronger interfacial interaction of PS and PPC. These results indicate that blending PPC with PS is an efficient and convenient method to improve the properties of PPC, and the composites can be used as a common packaging material for a wide range of applications.
This review examines recent advances in hydroformylation with formaldehyde, formic acid, and CO 2 as carbonyl surrogates, focusing on mechanisms, catalysts, substrates, limitations, and future opportunities.
2 December 2023 in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
The development of supramolecular materials has opened up unprecedented opportunities for smart, responsive systems. Yet, their practical application in extreme environments—deep space, deep sea, polar regions, high-temperature and high-pressure reservoirs—is fundamentally challenged by the inherent trade-off between structural stability and dynamic adaptability. This review addresses this core issue by presenting a comprehensive framework for understanding and overcoming the stability–dynamism mismatch under harsh condition. We systematically analyze the molecular mechanisms by which severe factors disrupt non-covalent networks. Based on these insights, we outline four universal molecular design strategies that re-establish the balance, and summarize engineering applications across aerospace, marine, energy, and polar exploration. Beyond offering a comprehensive roadmap for rational material design, this review highlights persistent challenges—including multi-field coupling failure mechanisms, industrialization barriers, and the limitations of current systems—and outlines future directions. By bridging fundamental chemistry with extreme environment engineering, this work aims to guide the next generation of supramolecular materials that can reliably serve in the most demanding operational scenarios.
The hydroesterification of olefins provides a highly efficient way to produce high value-added ester products from simple and abundant olefin feedstocks. In this work, DFT calculation was performed to investigate the detailed reaction mechanism of propene hydroesterification over Rh(II)/Silicalite-2 catalysts. Three possible mechanistic pathways were systematically explored and compared in terms of their adsorption configurations, reaction energies, and transition-state barriers. Among them, the Carbonylation-First pathway exhibited the most favorable energy profile with the lowest overall kinetic barriers, indicating it to be the most likely way for ester formation. A comparison of methyl butyrate and methyl isobutyrate formation revealed that the linear product is energetically more favorable, particularly along the Carbonylation-First pathway. Moreover, the Rh(II) center demonstrates a different catalytic effect over conventional Rh(I) species by significantly lowering the energy barrier for CO insertion, a key step in both hydroformylation and hydroesterification. These findings provide fundamental insight into the role of Rh(II)/zeolite systems in carbonylation reactions and offer theoretical guidance for the design of catalysts.
We report a method for the synthesis of 2-substituted benzoxazoles from tertiary amides and 2-aminophenols in the presence of triflic anhydride (Tf2O) and 2-Fluoropyridine (2-F-Pyr). The cascade reaction involves the activation of the amide carbonyl group by Tf2O, nucleophilic addition, intramolecular cyclization, and elimination. Furthermore, we explore the scope of this method by varying both the amide and 2-aminophenol substrates, highlighting its versatility in the synthesis of a wide range of functionalized benzoxazole derivatives.