As a biobased and biodegradable polyester, polylactide (PLA) is widely applied in disposable products, biomedical devices, and textiles. Nevertheless, due to its inherent brittleness and inferior strength, simultaneously reinforcing and toughening of PLA without sacrificing its biodegradability is highly desirable. In this work, a robust assembly consisting of compact and well-ordered microfibrillar crystalline superstructure (FCS) surrounded by slightly oriented amorphism, is achieved by a combined external force field. Unlike the classic crystalline superstructures such as shish-kebabs, cylindrites, and lamellae, the newfound FCS with diameter of about 100 nm and length of several tens of micrometers is aggregated with well-aligned crystalline nanofibers. FCS can serve as discontinuous fiber to self-reinforce the amorphous PLA; more importantly, FCS can also act as rivets to pin the propagating fibrillar crazes leading to the formation of dense fibrillar crazes during stretching, which dissipates much energy and translates the failure of PLA from brittle to ductile. Consequently, PLA with FCS exhibits exceptionally simultaneous enhancement in ductility, strength, and stiffness, outperforming normal PLA with increments of 728, 55, and 70% in elongation at break, strength, and modulus, respectively. Therefore, FSC exhibits competitive advantages in achieving high-performance PLA even for other semicrystalline polymers. More significantly, this newfound crystalline superstructure (FCS) provides a new structural model to establish the correlation between structure and performance.

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An interesting cooperation between Candida antarctica Lipase B (CAL-B) and alkaline protease from Bacillus subtilis (BSP) in the copolymerization of bulky ibuprofen-containing hydroxyacid methyl ester (HAEP) and ε-caprolactone (ε-CL) is observed. This cooperation improved the M¯n of the polymers from 3130 (CAL-B) to 9200 g mol (CAL-B/BSP). Experimental results clearly indicate that CAL-B mainly catalyzes the ring-opening polymerization (ROP) of ε-CL under the initiation of HAEP to form the homopolymer of ε-CL, while BSP catalyzes the subsequent polycondensation of the ROP product to yield the copolymer with increased molecular weight. Furthermore, using suitable chemo-enzymatic methods, valuable polyesters with chiral (R)- or (S)-ibuprofen pendants can be tailor-made.

SAPO-5 molecular sieves (E-SAPO-5) were synthesized ionothermally in 1-ethyl-2,3-dimethylimidazolium bromides ([EMMIM] Br) ionic liquid (IL). The samples were characterized by X-ray diffraction (XRD), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), N 2 isothermal adsorption-desorptionand, temperature-programmed desorption of ammonia (NH 3 -TPD) and fourier transform infrared (FT-IR) spectroscopy. Moreover, the catalytic performances of the samples in the methanol conversion reaction were investigated. Relative to the hydrothermal method, ionothermal synthesis favored the formation of large silica islands mainly by the SM3 substitution mechanism and decreased the B acid sites and the strong acid and total acid amounts of E-SAPO-5, which significantly influenced the distribution of the products in the methanol conversion reaction. Methanol underwent the methanol-to-dimethyl-ether (MTD) reaction and methanol-to-olefin (MTO) reaction over the E-SAPO-5 and hydrothermally synthesized SAPO-5, respectively. E-SAPO-5 exhibited high MTD activity at the high temperature of 450°C with methanol conversion of 100% and dimethyl ether (DME) selectivity of 86.6%.[a] J.

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Summary In this paper, guaranteed cost control for a class of switched linear systems subject to time delays is investigated, where a nonweighted quadratic performance index is considered. In particular, a novel quasi‐time‐dependent Lyapunov‐Krasovskii function based on a time‐varying positive definite matrix is proposed that is decreasing during the switching intervals and at the switching instants. By exploiting this interesting property, a family of stability condition based on mode‐dependent dwell time is developed to guarantee asymptotic stability of the considered switched linear system. Moreover, design condition for the quasi‐time‐dependent state feedback controller is formulated by extending the stability conditions, guaranteeing asymptotic stability of the closed‐loop system and an initial‐condition‐dependent upper bound of the performance index. A computationally traceable optimization problem is presented to minimize the proposed upper bound as well. A numerical example is considered to show the effectiveness of the proposed control method.