The Crystallization and Melting Behaviors of PDLA-b-PBS-b-PDLA Tri-block Copolymers

In this study,the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA)triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized,and the crystallization behaviors of the PDLA and PBS blocks are investigated.Although both the crystallization behaviors of PBS and PDLA blocks depend on composition,they exhibit different variations.For the PDLA block,its crystallization behaviors are mainly influenced by temperature and block length.The crystallization signals of PDLA block appear in the B-D 2-2 specimen,and these signals get enhanced with PDLA block length.The crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100°C.Crystallizing at higher temperature,the crystallization rates increase at first and then decrease with block length.The crystallization rates decrease as elevating the crystallization temperature.The melting temperatures of PDLA blocks increase with block lengths and crystallization temperatures.For the PBS block,its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA block.The crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized,while the crystallization rates of the PBS block exhibit unique component dependence,and the highest rate is observed in the B-D 2-2 specimen.The Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher temperature.This investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.     

Synthesis,crystal structure and optical property of manganese (II) halides based on pyridine ionic liquids with high quantum yield

Transition Metal Chemistry - Two novel tetrahedral Mn (II) halide single-crystals [(C7H10N)2][MnCl4] (1) and [(C7H10N)2][MnBr4] (2), based on pyridine ionic liquids, have been successfully...     

Methanol synthesis from CO2: a DFT investigation on Zn-promoted Cu catalyst

Research on Chemical Intermediates - The reaction steps during methanol synthesis from CO2/H2 are influenced by the type of catalysts such as pure Cu and Zn-decorated Cu. In this study, density...     

Multiple Stimuli-Responsive Conformational Exchanges of Biphen[3]arene Macrocycle

Conformational exchanges of synthetic macrocyclic acceptors are rather fast, which is rarely studied in the absence of guests. Here, we report multiple stimuli-responsive conformational exchanges between two preexisting conformations of 2,2′,4,4′-tetramethoxyl biphen[3]arene (MeBP3) macrocycle. Structures of these two conformations are both observed in solid state, and characterized by ¹H NMR, ¹³C NMR and 2D NMR in solution. In particular, conformational exchanges can respond to solvents, temperatures, guest binding and acid/base addition. The current system may have a role to play in the construction of molecular switches and other stimuli-responsive systems.     

Responsive Exosome Nano‐bioconjugates for Synergistic Cancer Therapy

Exosomes hold great potential in therapeutic development. However, native exosomes usually induce insufficient effects in vivo and simply act as drug delivery vehicles. Herein, we synthesize responsive exosome nano‐bioconjugates for cancer therapy. Azide‐modified exosomes derived from M1 macrophages are conjugated with dibenzocyclooctyne‐modified antibodies of CD47 and SIRPα (aCD47 and aSIRPα) through pH‐sensitive linkers. After systemic administration, the nano‐bioconjugates can actively target tumors through the specific recognition between aCD47 and CD47 on the tumor cell surface. In the acidic tumor microenvironment, the benzoic‐imine bonds of the nano‐bioconjugates are cleaved to release aSIRPα and aCD47 that can, respectively, block SIRPα on macrophages and CD47, leading to abolished “don't eat me” signaling and improved phagocytosis of macrophages. Meanwhile, the native M1 exosomes effectively reprogram the macrophages from pro‐tumoral M2 to anti‐tumoral M1.     

The effect of polymer dispersions on the early hydration of calcium sulfoaluminate cement

The influence of three polymer dispersions [styrene–butadiene copolymer (SB), styrene–acrylic ester copolymer (SA) and polyacrylic ester (PA)] on the hydration of calcium sulfoaluminate (CSA) cement within 72 h was investigated by using isothermal conduction calorimetry, X-ray diffraction analysis and thermal gravimetric analysis. The results indicate that these three polymer dispersions perform different influences on the hydration heat flow of CSA cement during different periods, they all postpone the occurrence time of the maxima peaks, and its extent is mainly dependent on the addition amount. Polymer dispersions manifest great retardation on the initial hydration of CSA cement, and the effect is much more significant within 1 h. In this stage, the generation of ettringite is strongly delayed; however, the formation of ettringite is accelerated by these polymer dispersions at and after 2 h. Among these three polymer dispersions, PA demonstrates the highest acceleration effect on the hydration degree.

     

Investigation on the structure,fluoride vaporization and crystallization behavior of CaF2–CaO–Al2O3–(SiO2) slag for electroslag remelting

Journal of Thermal Analysis and Calorimetry - The structure, vaporization behavior and crystallization of CaF2–CaO–Al2O3 slags with different SiO2 contents for electroslag remelting...     

Study on calculation method of condensation heat transfer for non-azeotropic hydrocarbon mixtures in helically coiled tubes

Journal of Thermal Analysis and Calorimetry - We investigated the release behaviors and reaction reactivities of gaseous products during CO2 gasification of three chars (Guanghui char, Hongshagang...     

Combustion behavior and thermal stability of TPU composites based on layered yttrium hydroxides and graphene oxide

Journal of Thermal Analysis and Calorimetry - Layered yttrium hydroxides (LYH)- and graphene oxide (GO)-supported layered yttrium hydroxides (GO–LYH) were synthesized by a co-precipitation...