Melt blending is an effective way to prepare new composite materials, but most polymers are incompatible. In order to reduce the interfacial tension and obtain fine and stable morphology with internal symmetric micro-textures, suitable compatibilizers should be added to the blend. The two immiscible polymers, low-density polyethylene (LDPE) and polystyrene (PS), were compatibilized by styrene/ethylene/butylene/styrene block copolymers grafted with maleic anhydride (SEBS-g-MAH) and organomontmorillonite (OMMT). The scanning electron microscope results indicated that the size of the PS phase decreased with increasing the content of SEBS-g-MAH. By introducing OMMT into LDPE/PS/SEBS-g-MAH composites, the compatibility of composites was further improved. The rheological analysis and Cole–Cole plot analysis indicated that the addition of SEBS-g-MAH and OMMT increased the interaction between the two phases. The tensile strength, elongation at break, and impact strength of the LDPE/PS/SEBS-g-MAH (70/30/7, wt%) composite increased by 64%, 255%, and 380%, respectively, compared with the LDPE/PS (70/30, wt%) composite. A small amount of OMMT could synergistically compatibilize the LDPE/PS composite with SEBS-g-MAH. After adding 0.3% OMMT into the LDPE/PS/SEBS-g-MAH system, the tensile strength, elongation at break, and impact strength of the composite were further increased to 18.57 MPa, 71.87%, and 33.28 kJ/m², respectively.

(S)-N-Boc-3-hydroxypiperidine is an important intermediate of the anticancer drug ibrutinib and is mainly synthesized by the asymmetric reduction catalyzed by ketoreductase coupled with glucose dehydrogenase at present. In this study, the coexpression recombinant strains E. coli/pET28-K-rbs-G with single promoter and E. coli/pETDuet-K-G with double promoters were first constructed for the coexpression of ketoreductase and glucose dehydrogenase in the same cell. Then, the catalytic efficiency of E. coli/pET28-K-rbs-G for synthesizing (S)-N-Boc-3-hydroxypiperidine was found to be higher than that of E. coli/pETDuet-K-G due to the more balanced activity ratio and higher catalytic activity. On this basis, the catalytic conditions of E. coli/pET28-K-rbs-G were further optimized, and finally both the conversion of the reaction and the optical purity of the product were higher than 99%. In the end, the cell-free extract was proved to be a better catalyst than the whole cell with the improved catalytic efficiency of different recombinant strains. This study developed a better coexpression strategy for ketoreductase and glucose dehydrogenase by investigating the effect of activity ratios and forms of the biocatalysts on the catalytic efficiency deeply, which provided a research basis for the efficient synthesis of chiral compounds.