We report a comprehensive understanding of the stereoselective interaction between two opposite enantiomeric polyesters prepared from the regio­selective copolymerization of chiral terminal epoxides and cyclic anhydrides. For many of the resultant polyesters, the interactions between polymer chains of opposite chirality are stronger than those of polymer chains with the same chirality, resulting in the formation of a stereocomplex with an enhanced melting point (T m) and crystallinity. The backbone, tacticity, steric hindrance of the pendant group, and molecular weight of the polyesters have significant effects on stereocomplex formation. Bulky substituent groups favor stereocomplexation, resulting in a greater rise in T m in comparison to the component enantiomeric polymers. The stereocomplex assembly of discrete (R)- and (S)-poly­(phenyl glycidyl ether-alt-phthalic anhydride)­s oligomers revealed that the minimum degree of polymerization required for stereocomplex formation is five. Raman spectroscopy and solid-state NMR studies indicate that stereocomplex formation significantly restricts the local mobilities of CO and C–H groups along the backbone of chains. The reduced mobility results in the enhanced spin–lattice relaxation time and both 1H and 13C downfield shifts due to the strong intermolecular interactions between R- and S-chains.

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An aliphatic polyester has been prepared from ethylene oxide and maleic anhydride that undergoes reversible transformation between amorphous (T g = 18 8 8C) and crystalline (T m = 124 8 8C) states through cis-trans isomerization of the C=Cb onds in the polymer backbone without any change in either the molecular weight or dispersity of the polymer.A similar transformation was also observed in chiral unsaturated polyesters formed from enantiopure terminal epoxides,such as epichlorohydrin, phenyl glycidyl ether,and (2,3-epoxypropyl)benzene. These unsaturated polyesters with 100 %E -configuration in the crystalline state were prepared by quantitative isomerization of their Z-configuration analogues in the presence of ac atalytic amount of diethylamine,w hile in the presence of benzophenone,i rradiation with 365 nm UV light resulted in the transformation of about 30 %t rans-alkene to cis-maleate form, thereby affording amorphous polyesters.

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It has been a challenging task to manage perishable food supply chains because of the perishable product's short lifetime, the possible spoilage of the product due to its deterioration nature, and the retail demand uncertainty. All of these factors can lead to a significant amount of shortage of food items and a substantial retail loss. The recent development of tracing and tracking technologies, which facilitate effective monitoring of the inventory level and product quality continuously, can greatly improve the performance of food supply chain and reduce spoilage waste. Motivated by this recent technological advancement, our research aims to investigate the joint decision of pricing strategy, shelf space allocation, and replenishment policy in a single-item food supply chain setting, where our goal is to maximize the retailer's total expected profit subject to stochastic retail demand. We prove the existence of optimality for the design of the perishable food supply chain. We then extend the single-item supply chain problem to a multi-item setting and propose an easy-to-implement searching algorithm to produce the optimal allocation of shelf space among these items for practical implementation. Finally, we provide numerical examples to demonstrate the effectiveness of our solution.