External stimuli can induce composition conversion in block copolymers, which can then lead to morphological transitions of the block copolymer aggregates from one ordered state to another, which has become a new strategy for regulating the morphological structure of block copolymers. Based on this, taking the classical ABA triblock copolymer ordered aggregates (such as cylinders and vesicles) as the initial state, the Monte Carlo simufation imetitor was used to investigate the microstructital changes in the hydrophobic parts of the cylinder and vesicle when part of the B blocks in the system were converted into C blocks (i.e., the ABA triblock copolymer in the system was transformed into the ABA/ACA triblock copolymer mixture). The simulation results indicated that by regulating the incompatibility between the B block and the newly generated C block, as well as the evolution time of the system, ordered aggregates with a single hydrophobic component could evolve into ordered aggregates with a variety of novel controllable multi-compartment structures that are rarely observed in linear terpolymer systems, such as segmented worm, Hamburg-type and Janus-type rods, pupa-like vesicles, softball-shaped vesicles, Janus-type and dumbbell-shaped vesicles. It is worth noting that some of the aforementioned structures, such as segmented worms and pupa-like vesicles, are difficult to obtain using traditional self-assembly methods (i.e., the system evolves from a disordered uniform solution state) under the same parameter conditions.

3D flower-like Gd3+-doped titanium dioxide (Gd3+-TiO2) catalysts were designed and synthesized via a facile hydrothermal method. The catalysts featured an interwoven lamellar network, anatase crystal phase, Gd-O-Ti bonds, abundant oxygen vacancies, and weak Lewis acidity. Among the series, Gd3+-TiO2-0.5% (0.5% mol/mol of TiO2) exhibited optimal performance, with acid amount of 260.92 mu mol/g, specific surface area of 79.13 m2/g, and average pore diameter of 23.81 nm. Notably, its catalytic performance outperformed that of several representative metal catalysts (e.g., tin(II) oxalate, GeO2) and the organic catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The resultant PEF possessed a high number-average molecular weight (Mn) of 6.7 & times; 104 g/mol, low ether bond content of 2.8%, excellent optical transparency and color, a prolonged crystallization half-time (t1/2) of 22.72 min, and superior thermal stability. The elastic modulus (Et) and maximum tensile stress (sigma) of PEF film were 2256 +/- 38 MPa and 64 +/- 11 MPa, respectively. This work provides a feasible strategy for fabricating advanced catalysts via 3D structural engineering and rare-earth doping, which holds great promise for the synthesis of high-performance bio-based polyesters.

The self-assembly behavior of cyclic A12B12C12 terpolymers under 3D soft confinement were studied using Monte Carlo simulation. The simulation results indicate that under neutral boundary conditions, the cyclic A12B12C12 terpolymers self-assemble into nanoparticles with intriguing ordered inner nanostructures, i.e., each component forms hexagonally packed short cylinders arranged in the nanoparticles. It is worth noting that the overall shape of those nanostructured particles can be tuned via changing the interfacial interactions between different blocks (εPP) and the interfacial interactions between the terpolymers and solvents (εPS), and the nearly flat oblate nanoparticles can be obtained in the case of large εPP while small εPS. In addition, via changing the confinement degree, the number of short cylinders in the particles can be easily tuned, which leads to the formation of oblate nanoparticles with various internal nanostructures, and core-multi-petal oblate nanoparticles with one component forming the core and the other two components forming the petals can be obtained when the confinement degree is relatively strong. It should be noted that the core-forming component in the core-multi-petal nanoparticles can be easily tuned via introducing the selectivity of the solvents. Our simulation results indicate that the cyclic ABC terpolymers is a good candidate for the preparation of oblate nanoparticles with controllable inner nanostructures.

Various external stimuli, such as pH, light, and temperature, have been widely used to trigger the hydrophobic-hydrophilic transition of a certain block in block copolymer, which has become a commonly used and effective strategy to induce the disassembly of vesicles for controlled drug release. Based on this, the disassembly behavior of the ABCA tetrablock asymmetric vesicles induced by the hydrophobic-hydrophilic transition of block C was studied using Monte Carlo simulation. In this work, the hydrophobicity of block C was tuned to mimic the hydrophobic-hydrophilic transition triggered by external stimuli. As the hydrophobicity of block C decreases, the initial ABCA asymmetric vesicles disassemble into a series of ordered aggregates such as Janus lamella, reversed asymmetric vesicle, toroid micelle, ring-like micelle and cylindrical micelle. It should be noted that these aggregates disassembled from the initial vesicle state cannot be obtained through the traditional selfassembly method from homogeneous states of the ABCA tetrablock terpolymers under the same conditions. The simulation results show that the hydrophobicity changing rate of block C has a significant effect on the disassembly pathway from the initial asymmetric vesicle to the reversed asymmetric vesicle. It is found that during the disassembly from the initial to the reversed vesicles, the system will undergo an energy-driven process first, then followed by an entropy-driven process. In addition, the simulation results further indicate that the disassembly behavior of the initial ABCA asymmetric vesicles is irreversible.

The composition conversion in block copolymer induced by external stimuli such as light and pH is an effective strategy to trigger the disassembly of vesicles experimentally. Based on this strategy, the disassembly behavior of the A2B12A2 triblock copolymer vesicle induced by the composition conversion from B block to C block was studied using Monte Carlo simulation. In this study, a part of the B block in the A2B12A2 triblock copolymer was converted to the new block C with weaker hydrophobicity, forming the A2B12-nCnA2 tetrablock copolymer. The composition conversion makes the originally stable vesicle unstable, and after sufficiently long simulation time, the system reached a new equilibrium state. The aggregate morphology of the new equilibrium state was highly dependent on the converted chain length (n). A variety of micelles with novel Janus-type phase-separated microstructures in their hydrophobic parts have been observed in the systems with different n. It should be noticed that those Janus-type micelles cannot be obtained via traditional self-assembly processes from homogeneous states of A2B12-nCnA2 tetrablock copolymers under the same conditions. The simulation results further indicated that the morphological transformation from ABA vesicle to ABCA micelles induced by the composition conversion is reversible.

The self-assembly behaviors of the mixtures composed of linear and cyclic AB diblock copolymers in A-selective solvents are investigated by means of Monte Carlo simulation. The simulation results indicate that a typical morphological transition of the aggregate from sphere to cylinder, to lamella, and then to vesicle can be achieved via solely adjusting the molar fraction of the cyclic diblock copolymers in the mixture. Furthermore, the simulation results show that under the condition that the pure cyclic and linear diblock copolymers can both form vesicles, the structure characteristics (e.g., the inner radius and hydrophobic membrane thickness of the vesicle) and the formation pathway of the vesicles formed by the mixtures can also be regulated via solely changing the molar fraction of the cyclic diblock copolymers in the mixture. It is worth noting that the inner radius of the vesicle can be considerably increased by increasing the molar fraction of the cyclic diblock copolymers in the mixture, which results in a remarkable increase in the inner capacity of the vesicle. This phenomenon has a unique significance in the field of drug delivery. Our simulation works can provide a new approach to the preparation of polymer materials with novel properties and functions.

Poly(butylene adipate-co-butylene terephthalate) (PBAT)/thermoplastic starch (TPS) blends were prepared by melt blending. However, the processability and practical application of PBAT/TPS blends are limited by their poor compatibility. To enhance the compatibility between PBAT and TPS, PBAT was functionalized by maleic anhydride (MA) to prepare PBAT-MA, and then it was employed as a compatibilizer for PBAT/PBAT-MA/TPS blends. The effects of PBAT-MA on the tensile properties, rheological properties, morphology, and dynamic mechanics of PBAT/PBAT-MA/TPS blends were studied in detail. Rheological results revealed that the interaction between PBAT-MA and TPS enhanced the segment entanglement ability and improved the compatibility of the blends, which enhanced the tensile properties of the blends. Compared with the PBAT/PBAT-MA/TPS (50/0/50) blend, the tensile strength of the PBAT/PBAT-MA/TPS (40/10/50) blend increased from 9.2 to 15.8 MPa, and the elongation at break increased from 326.9% to 1017.6%. The dynamic mechanical results showed that the T-g of PBAT and TPS were close to each other after the addition of PBAT-MA, which confirmed that the compatibility of the blend was improved. This study provides a feasible approach to preparing high-performance and cost-effective PBAT/PBAT-MA/TPS blends while expanding the application prospects of PBAT in the packaging industry and agricultural film.

In the study, poly (butylene adipate-co-terephthalate) (PBAT) was grafted with glycidyl methacrylate (GMA) in the presence of the co-monomer N-vinyl pyrrolidone (NVP), and then it was employed to enhance the toughness of poly (lactic acid) (PLA). It was found the functionalized PBAT had a better toughening effect on PLA than neat PBAT. The PLA/PBAT-GMA (70/30) blend undergoes brittle-ductile transition when the graft monomer ratio of GMA:NVP:DCP exceeds 2:2:0.2. The impact strength of PLA/PBAT-GMA (3:3:0.3) blend reached 65.7 kJ/m2, with an elongation at break of 210.9 %. Additionally, rheological tests showed that the entanglement ability of chain segments was enhanced, it was ascribed to the improvement of the compatibility between PLA and PBAT-GMA owing to the compatibilization reaction between the epoxy functional groups in PBAT-GMA and the carboxyl groups in PLA, resulting in the formation of a new copolymer. DMA tests revealed that the Tg of PLA and PBAT-GMA were close to each other, confirming the improved compatibility of the PLA/PBAT-GMA blends. This offers a novel method for preparing super-though PLA.

Abstract Background Heterologous synthesis presents a promising new approach for accessing the active ingredients of traditional Chinese medicine (TCM), contributing to the conservation of natural medicinal resources. Compound Danshen preparation, a widely used TCM formulation, is designed to treat coronary heart disease and angina pectoris. It is primarily composed of Salviae Miltiorrhizae Radix et Rhizoma (Danshen), Notoginseng Radix et Rhizoma (Sanqi), and borneol (Bingpian). Danshen primarily yields tanshinones and phenolic acids, while Sanqi produces notoginsenosides. Borneol serves as an auxiliary agent to promote mental clarity, dissipate heat, and relieve pain. Objectives The objective is to employ heterologous synthesis in a single yeast strain to produce the active ingredients of Compound Danshen preparation, and these include notoginsenosides, tanshinones, and borneol. Methods Firstly, the “plug-and-play” terpene synthase screening framework in Saccharomyces cerevisiae was used for the identification of a novel, highly efficient bornyl diphosphate synthase. Furthermore, by leveraging the Compound Danshen preparation as a basis to concurrently reconstruct the biosynthetic pathways for the notoginsenoside precursor protopanaxadiol (a triterpene), the tanshinone precursor miltiradiene (a diterpene), and borneol (a monoterpene) within a single yeast strain. Results This engineered strain, termed Compound Danshen Yeast 1.0, successfully produced protopanaxadiol at 62.34 mg/L, miltiradiene at 15.38 mg/L, and borneol at 2.54 mg/L in shake-flask fermentation. Conclusions This research signifies the inaugural cross-species and multicomponent synthetic biology endeavor that enables the synthesis of active ingredients in engineered cells, setting the stage for the industrial manufacture of TCM compounds.

高分子基柔性电容式压力传感器具有机械柔韧性、高灵敏度、优异的可重复性、功耗低、空间分辨率高等优点,在可穿戴电子器件、电子皮肤等领域的应用越来越广泛,引起了人们的广泛关注.本文首先对不同传感机理的压力传感材料进行简要介绍,然后重点论述了高分子基柔性电容式压力传感材料的研究进展,并对其传感机理、优缺点以及优化策略进行了详细讨论.最后,本论文还对电容式压力传感材料目前存在的问题及未来发展趋势进行了展望.

In order to quantitatively study the effect of the modulus ratio of matrix polymer to toughening modifier on the brittle-ductile transition (BDT) of the blends, the modulus ratio of polypropylene (PP) to impact modifier at various temperatures was obtained from dynamic mechanical analysis (DMA) results. The modulus ratio changed continuously from nearly 1 to more than 100 by increasing temperature from − 100 to 50 °C. Accordingly, the impact property of the PP/POE blends within a wide composition range was studied at various temperatures by notched impact strength test. The variations of the notched impact strength with the modulus ratio were thereby obtained for various PP/POE blends. The result shows that a clear sharp BDT appeared with increasing the modulus ratio and the critical modulus ratio is 10, that is, the modulus of impact modifier must be one tenth of that of polymer matrix in order to be effective. In addition, the effect of the microstructure on the BDT of PP/POE blends was also studied.

The self-assembly behavior of a tadpole-like giant molecule (TGM) constructed from a hydrophobic nanoparticle (NP) monotethered by a single amphiphilic AB diblock copolymer chain was investigated by combining self-consistent field theory and density functional theory in solution. The effects of the hydrophobicities of the B blocks and NPs (i.e., solvent properties) on the self-assembly behavior of the TGMs were investigated in the cases of weak and strong intramolecular interactions (i.e., incompatibilities) between the components of giant molecules, respectively. Besides conventional ordered aggregates (such as spheres, rings, and vesicles) with hydrophobic B-cores covered by NP shells, several aggregates with novel hierarchical structures, including vesicles with NP-inserted hydrophobic walls, bead-string-like micelles, and long cylindrical micelles with NP bumps, were obtained by tuning the solvent properties under different intramolecular interactions. Noteworthy that the simulation results show that the arrangement of the NP bumps on the long cylindrical micelles may have a certain degree of helicity, which means that these micelles may have some unique electromagnetic features such as circular dichroism. Phase diagrams as a function of the hydrophobicities of the B blocks and NPs were constructed to show the formation conditions of these novel structures. These findings can not only offer new insights into understanding of the self-assembly behavior of the TGM in solution but also provide useful guidance for simple and efficient regulation of the morphology, as well as the NP distribution and arrangement of the ordered aggregates in experiments.

The existence of impurities in monomers is an inescapable problem in polymerization, which influences the polymerization reaction and resulting polymers. However, it is difficult to study this influence by experimental method quantitatively. In this work, the effects of two kinds of impurities in AA monomer, i.e., CC impurity without a reactive group and AC impurity with one group (A) that can react with BB monomer on AA-BB polycondensation are studied by using Monte Carlo simulation. The simulation results show that the existence of the two impurities in AA monomer reduces the degree of polymerization (DP) of the resulting polymers and prolongs polymerization time. The existence of 0.5% impurity can lead to a 33% decrease in DP, and the molecular weight reduces by half if the content increases from 0 to 1% for both CC and AC impurities when the extent of reaction reaches 0.995. Moreover, the simulation results indicate that impurities can affect the molecular weight distribution (MWD) and the polymerization rate. The peak of MWD shifts to a lower degree of polymerization and becomes narrow, and the polymerization rate decreases considerably with increasing impurity content. Graphical abstract An inescapable problem for polycondensation is the purity of monomers because the impurities can result from various external factors. Monte Carlo method is used to study the reaction in the presence of different impurities which affect the purity of monomer. The variations in molecular weight and molecular weight distribution are quantitatively obtained.

The plasticized starch exhibits flexible properties, similar to that of elastomer. In this paper, thermoplastic starch acetate (TPAS) and maleic anhydride grafted poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS-MAH) were used to toughen polypropylene (PP) through melt blending. It is found TPAS and SEBS-MAH have a synergistic toughening effect on PP, especially the notched impact strength of PP/TPAS/SEBS-MAH (70/15/15) blend is as high as 83.4 kJ/m(2), but only 7.2 kJ/m(2) of that for PP/TPAS/SEBS (70/15/15) blend. The structure-property relationship of the PP/TPAS/SEBS-MAH blends was investigated. Compared with PP/TPAS/SEBS (70/15/15) blend, the TPAS domains are dispersed homogeneously in the PP/TPAS/SEBS-MAH (70/15/15) blend with the domain size of TPAS less than 0.2 mu m. The incorporation of SEBS-MAH not only improves the compatibility between PP and TPAS but also facilitates the formation of a core-shell structure with TPAS as the core and SEBS-MAH as the shell. Thus formed core-shell particles play an important role in toughening PP. The spreading coefficient of the multiphase blend reveals that only when the SEBS-MAH content is higher than TPAS, the core-shell structure can be formed. Otherwise, TPAS and SEBS-MAH will disperse separately and the toughness will not be improved. This work provides a new insight into polymer toughening with TPAS.

Poly(butyleneadipate-co-terephthalate) (PBAT) was used to toughen poly(lactic acid) (PLA) with the addition of poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) (MAM) through melt blending. The impact toughness and tensile toughness of the PLA/PBAT/MAM ternary blends were greatly enhanced when the MAM content was higher than 5%. For PLA/PBAT/MAM (80/15/5) blend, the notched impact strength was as high as 42.4 kJ/m(2), and the elongation at break reached 194.7%. The structure-property relationship of the PLA/PBAT/MAM ternary blends were studied through scanning electron microscopy, dynamic mechanical analysis, and contact angle measurements. It is found MAM and PBAT have a synergistic toughening effect on PLA, the MAM acts as not only a compatibilizer but also a toughening agent, which can improve the compatibility and enhance the interfacial adhesion between PLA and PBAT. As a result, the overall mechanical properties of PLA blends were improved significantly. This result provides a simple to operate and more efficient method for PLA toughening.

The interfacial nanoparticle compatibilization (INC) strategy has opened up a promising avenue toward simultaneous functionalization and interfacial engineering of immiscible polymer blends. While the INC mechanism has been well developed recently, few investigations have focused on rigid nanoplatelets because of the inherent steric hindrance of the surface-grafted polymer chains. Herein, surface-modified rigid nanoplatelets have been incorporated into an immiscible poly(l-lactide) (PLLA)/poly(butylene succinate) (PBSU) blend. It is demonstrated that the strong interfacial adhesion between PLLA and PBSU phases is promoted via molecular entanglements of the grafted chains on the surface of nanoplatelets with the individual components. A refined phase morphology with improved mechanical properties can be achieved with the addition of 5 wt % modified Gibbsite nanoplatelets. It was further found that the stiffness of nanoplatelets can change the geometry of the interface significantly. It is, therefore, indicated that the simultaneous interface strengthening and interfacial curvature controlling of rigid nanoplatelets originate from the selective swelling/collapse of the in situ-formed PLLA and PBSU grafts within the corresponding phase at the interface. Such a mechanism is confirmed by the Monte Carlo simulations. This work provides new opportunities for the fabrication of advanced polymer blend nanocomposites.

采用Monte Carlo模拟方法研究了线性ABC三嵌段共聚物在B嵌段的选择性溶剂中的自组装行为.模拟结果表明,改变B嵌段的亲水性,体系可以自组装得到多种形貌各异的胶束.随着亲水性的减弱,胶束发生了从Janus球状多核胶束到多间隔胶束再到圆盘状多核胶束的转变.通过进一步分析胶束中聚合物的链构象等微观结构信息,我们发现随着亲水程度的减弱,聚合物链构象发生了从伸展状态到伸展、折叠状态并存,最终再到伸展状态的一系列转变.

聚合物囊泡是由两亲性嵌段共聚物制备而成的一种具有独特中空结构的纳米聚集体.聚合物囊泡的中空结构、囊泡的内外亲水冠以及亲水冠中间膜层的两亲性赋予了聚合物囊泡选择性封装亲水性和疏水性药物的能力,这使得聚合物囊泡在药物负载与释放、靶向识别等生物医药领域具有潜在的应用价值.聚合物囊泡能否实现其潜在应用价值还依赖于人们能否精准调控聚合物囊泡的膜冠结构、尺寸以及尺寸均一性等微观结构参数.因此,本文针对近期有关嵌段共聚物囊泡尺寸均一性和聚合物囊泡膜冠结构调控的研究进展进行了介绍,从而使人们通过物理手段有效地调控聚合物囊泡的微观结构,为制备膜冠结构可控、尺寸均一的聚合物囊泡提供新思路.

The self-assembly behavior of ABC triblock terpolymers with hydrophobic-hydrophilic-hydrophobic (H-P-H)sequence in selective solvent of B blocks was studied by means of Monte Carlo simulation. The simulation results show that various micelles with different morphologies can be formed by adjusting the hydrophobicity and the incompatibility of A and C blocks. According to the characteristics of hydrophobic core structures in the micelles, these micelles can be generally divided into two types:multicore micelles and multicompartment micelles. By increasing the hydrophobicity of hydrophobic blocks or reducing the incompatibility be. tween A and C blocks, the micelles formed by H-P-H type ABC triblock terpolymers can transform from multi. core micelles to multicompartment micelles. Via further investigation on the chain conformations in typical micelles, it is found that there is competition between the hydrophobic interaction and the repulsion between A and C blocks, and this competition is the main factor that determines whether the multicore micelles or the multicompartment micelles can be formed by ABC triblock terpolymers with H-P-H sequence.

A facile yet universal approach to the self-assembly of uniform polymeric nanovesicles into bilayer supervesicles is developed using a water-in-1-butanol emulsion soft-confined system. The enclosed bilayer is constructed by polymeric nanovesicles, forming hierarchical supervesicles. Interestingly, the bilayer structure of supervesicles from symmetry to asymmetry is well tailored by simply mixing two different sizes of uniform nanovesicles. The larger nanovesicles are more likely to be segregated in the outer layer, while the smaller nanovesicles tend to be segregated into the inner layer, forming asymmetric hierarchical supervesicles. Different cargoes can thereby be well selectively encapsulated into the inner-layer and outer-layer multicompartment of the asymmetric supervesicles by loading different cargoes into the cavities of the original vesicles with different sizes separately. Such selectable multicompartmental encapsulation provides the possibility to realize the multiple functions of polymeric vesicles and has not been reported to date.