Metal-organic frameworks (MOFs) are considered to be promising materials for drug delivery. In this work, a Zinc-based MOF nanocomposite IRMOF-3 was introduced as a drug carrier for ...10-hydroxycamptothecine (HCPT). Without an extra drug-loading process, a nanoscale drug delivery material HCPT@IRMOF-3 was prepared via one-pot synthesis. The composition and structure of the material were investigated, and the drug release character was measured. Compared with preparing IRMOF-3 first and loading the drug, the one-pot-prepared HCPT@IRMOF-3 exhibited a higher drug-loading capacity. The material presented pH-responsive release. The HCPT release rate at pH 5.0 was significantly higher than that at pH 7.4. The cytotoxicity experiments showed that IRMOF-3 was non-toxic, and HCPT@IRMOF-3 exhibited notable cytotoxicity to Hela and SH-SY5Y cells. One-pot synthesis is a simple and rapid method for the preparation of an MOF drug delivery system, and IRMOF-3 can be potentially used in pH-responsive drug delivery systems.
Owing to the excellent properties of high selectivity, high thermal stability, and low cost, in the past twenty years, mixed protonic-electronic conducting hydrogen separation membranes have received ...extensive attention. In particular, dual-phase mixed protonic-electronic conducting membranes with high ambipolar conductivity are more attractive because of the high hydrogen permeability. This paper aimed to present a review of research activities on the dual-phase membranes, in which the components, the characteristics, and the performances of different dual-phase membranes are introduced. The key issues that affect the membrane performance such as the elimination of the inter-phase reaction, the combination mode of the phases, the phase ratio, and the membrane configuration were discussed. The current problems and future trends were simply recommended.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Membrane technology is an advanced hydrogen separation method that is of great significance in achieving hydrogen economy. Rare earth tungstate membranes have both high hydrogen permeability and ...remarkable mechanical/chemical stability, exhibiting good application prospects in hydrogen separation. This review provides the basic aspects and research progress on rare earth tungstate hydrogen separation membranes. The crystal structure, proton transport properties, and membrane stability under a chemical atmosphere are introduced. Different membrane construction designs, such as single-phase, dual-phase, and asymmetric rare earth tungstate membranes, are summarized. Lastly, the existing problems and development suggestions for tungstate membranes are discussed.
High-density polyethylene (HDPE) composites containing propylene-ethylene random copolymers (PEC) elastomer and carbon black (CB) were prepared by melt blending in an effort to obtain excellent ...balance of properties. HDPE matrix and PEC elastomer were immiscible, and CB fillers were selectively located in HDPE matrix. The introduction of CB fillers into the HDPE/PEC blend significantly improved the viscoelasticity of the composite melts. Percolation network of CB particles was formed at CB content of 5 wt%, which consequently largely improved the conductivity of composites, and the surface resistance decreased to 106 Ω (square)−1, equal to the antistatic range. DSC results suggested that CB with a content more than 5 wt% showed nucleation effect, improving the degree of crystallinity of HDPE. Moreover, the incorporation of CB improved stiffness of composites, and decreased ductility compare with HDPE/PEC blend. The combination of adjustable conductivity and mechanical properties, as well as improved melt viscoelasticity wold further broaden the application fields of HDPE based composites.
•HDPE/PEC/CB composites with balance of properties were prepared by melt blending.•CB particles were selectively located in HDPE matrix.•The composites melt showed the improved viscoelasticity.•The addition of CB improved the conductivity of HDPE/PEC blends.•The addition of CB increased the stiffness of HDPE/PEC blends.
A linear diamides derivative (TMC-300) was incorporated into biosourced and biodegradable poly(3-hydroxybutyrate-
co
-4-hydroxybutyrate) (P34HB) to investigate the influence of TMC-300 on ...the crystallization and rheological properties of P34HB. TMC-300 displayed an outstanding nucleating effect on P34HB. Adding 0.5 mass% TMC-300 increased the non-isothermal crystallization temperature by about 20 °C at rate of 5 °C min
−1
. Isothermal crystallization half-time at 95 °C obviously decreased from 20 min for neat P34HB to 2.5 min for P34HB/0.2TMC. Adding TMC-300 dramatically increased nucleation density and reduced spherulite size. Moreover, the rheological properties were obviously enhanced by adding TMC-300. The most intriguing result was that percolation network was formed at TMC-300 content between 0.5 and 1 mass%, which led to the transition of melt behaviors from liquid-like to solid-like. The unusual combination of nucleating effect and rheological properties promotion of TMC-300 on P34HB was in great potential for expanding practical application of biosourced and biodegradable P34HB.
In this work, the effect of uniaxial stretching on the crystallization and melting behaviors, miscibility, crystal structure, and mechanical properties of neat poly(L-lactide) (PLLA) and miscible ...PLLA/poly(vinyl acetate) (PVAc) blends was investigated. Stretching process could generate remarkable influence on thermal properties of neat PLLA and PLLA/PVAc blend. With stretching ratio increasing, macromolecular chains orientation and crystallization were promoted, resulting in a decrease in cold crystallization temperature and an increase in glass transition temperature, and a significant increase in crystallinity. In addition, after stretching process PVAc still inhibited the crystallization of PLLA. PLLA/PVAc blends were completely miscible blend system which had only one glass transition temperature before and after stretching process, and phase separation did not occur after stretching process. When stretch ratio increased, amorphous PVAc had greater influence on the tan
δ
transition peak and storage modulus increased markedly, which was benefit to the improvement of heat resistance. The
α
′ crystal form was produced in blends after stretching process. Stretching process with moderate stretch ratio can be utilized to improve the mechanical properties of PLLA with simultaneous enhancement of tensile strength, fracture strain and stiffness. The findings in this work provide an insightful understanding of the effect of stretching process on miscible PLLA blend and the improvement of toughness, which will facilitate the large-scale practical application of PLLA.
The inherent shortcomings of fully biodegradable poly(butylene adipate-co-terephthalate) (PBAT) copolyesters including low strength, modulus, and melt viscoelasticity were addressed by melt blending ...of PBAT with high-stiffness and biological poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB). An epoxy-based chain extender was used to increase interfacial adhesion of partially miscible PBAT/P34HB (70wt/30wt) blends. The addition of chain extender refined phase-separated morphology of blends from SEM and decreased the degree of crystallinity by DSC. Compared with neat PBAT, PBAT/P34HB blends with chain extender showed much higher melt viscosity and elasticity, as indicated by rheological properties analyses. Compared with the PBAT/P34HB blend without chain extender, the breaking strength and elongation at break of PBAT/P34HB blend with incorporation of 1 wt% ADR were increased by 91.8% and 58.7%, respectively. It could be concluded that the combination of blending and chain-extension reaction simultaneously improved the strength, elongation at break, and melt viscoelasticity, which contributed to the suitability of biodegradable polymer blends for a wider range of end-use applications.
A blend of biodegradable poly(ε-caprolactone) (PCL) and sustainable poly(propylene carbonate) (PPC) was prepared by melt mixing to obtain an excellent balance of performance. The miscibility, ...morphology, thermal behavior, mechanical, and rheological properties of PCL/PPC blends were investigated. Dynamic mechanical analysis results revealed PCL and PPC were immiscible. Minor phase-separated morphology was observed from SEM for PCL/PPC blends. The incorporation of PPC accelerated the crystallization rate of PCL, whereas reduced the degree of crystallinity. Significant enhancement of stiffness and strength of PCL was achieved by the introduction of PPC. The Young’s modulus and yield strength of blend containing 30 wt% PPC were increased by 65% and 17%, respectively, compared with neat PCL, and the elongation at break was still above 600%. Moreover, the viscosity and elasticity of PCL melt were improved by the presence of PPC. The synergetic improvement in mechanical and rheological properties is important for expanding the application of PCL.
Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) has gained significant attention because of its biodegradability and sustainability. However, its expanded application in some fields is limited ...by the brittleness and low melt viscoelasticity. In this work, poly(vinyl acetate) (PVAc) was introduced into PHBH/poly(propylene carbonate) (PPC) blends via melt compounding with the aim of obtaining a good balance of properties. Dynamic mechanical analysis results suggested that PPC and PHBH were immiscible. PVAc was miscible with both a PHBH matrix and PPC phase, while it showed better miscibility with PHBH than with PPC. Therefore, PVAc was selectively localized in a PHBH matrix, reducing interfacial tension and refining dispersed phase morphology. The crystallization rate of PHBH slowed down, and the degree of crystallinity decreased with the introduction of PPC and PVAc. Moreover, the PVAc phase significantly improved the melt viscoelasticity of ternary blends. The most interesting result was that the remarkable enhancement of toughness for PHBH/PPC blends was obtained by adding PVAc without sacrificing the strength markedly. Compared with the PHBH/PPC blend, the elongation at the break and yield strength of the PHBH/PPC/10PVAc blend increased by 1145% and 7.9%, respectively. The combination of high melt viscoelasticity, toughness and strength is important for the promotion of the practical application of biological PHBH.
A ternary blend of poly(L-lactic acid) (PLA), poly(ε-caprolactone) (PCL) and poly(vinyl acetate) (PVAc) was melt compounded with an aim to obtain novel biodegradable blends with a balance of ...performance. We systematically studied the relationship between the microstructure and macroscopic properties of the ternary blends. PVAc was miscible with both PLA an PCL. It was interesting that PVAc was selectively located in the PLA matrix of PLA/PCL/PVAc ternary blends, which significantly affected the crystallization behavior, mechanical and rheological properties, and enzymatic hydrolysis rate of the blends. The inhibited crystallization of PLA was achieved, whereas the crystallization of PCL was not affected by incorporating PVAc. Unexpectedly, increases of 10%, 17% and 26% were achieved in the yield strength, breaking strength and modulus of the ternary blend with 20 wt% PVAc compared to PLA/PCL binary blend, while the elongation at break maintained above 300%. Moreover, the rheological properties was enhanced and enzymatic hydrolysis rate was decelerated by introduction of PVAc. The excellent stiffness − toughness balance coupled with the enhanced melt viscoelasticity of the blends will help to expand the property range and processing methods of biodegradable polymers.
