Polymeric nano-carriers are considered as promising tools in biomedical applications due to multiple attractive characteristics including their low toxicity, high loading capacity, controlled drug release capabilities, and highly tunable chemical properties. Here, a series of pH-sensitive star-shaped copolymers, Ad-P[(EMA-co-MAA)-b-PPEGMA]4, was prepared via electron transfer atom radical polymerization (ARGETE ATRP) and selective hydrolysis. These star-shaped copolymers can be self-assembled into micelles (Dh = 150–160 nm) and their critical micelle concentrations (CMC) were estimated to be 3.9–5.0 mg/L. The pH-sensitiveness of the micelles was evidenced by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The maximal paclitaxel (PTX) loading efficiency (DLC) and entrapment efficiency (EE) were 18.9% and 36%, respectively. In vitro release studies revealed that about 19% of the PTX released at an acidic condition of pH 1.2 over 70 h, whereas more than 70% was released within the same time interval at pH 6.8. In vitro cytotoxicity suggested that the low cytotoxicity of the blank micelles, while the PTX-loaded micelles providing the cytotoxicity close to that of free PTX. These results indicated that this novel pH-sensitive nano-carriers have great potential applications for oral drug-controlled release.
1 May 2022 in Journal of the Electrochemical Society
Improving the flame retardant and electrochemical properties of electrolytes is of great significance to enhance the safety of lithium-ion batteries (LIBs). In this work, the effect of cresyl diphenyl phosphate (CDP), dimethyl methyl phosphonate (DMMP), trimethyl phosphate (TMP) and triphenyl phosphate (TPP) as flame retardant additives in the standard electrolyte on the performance of LiFePO 4 /Li cell are comprehensively studied. The results show that when the mass fraction of flame retardant is less than 20%, the purpose of flame retardant can be achieved in the electrolyte. When the cells without and with 20 wt% of CDP, DMMP, TMP, and TPP additives are, respectively, their capacity retentions are 80, 46, 82, 84, and 57% after 100 cycles at 0.5C. According to characterization analysis, DMMP and TMP can facilitate the formation of stable interface films on cathode and subsequently improve the battery performance. Compared with expensive or complicated synthetic flame retardants, conventional flame retardants like CDP, DMMP, TMP, and TPP have great potential for application in electrolytes to improve the safety of LIBs. This work can provide useful scientific research and industry in the study of phosphorus-based flame retardant electrolytes.
Microporous organic polymers and related porous materials have been applied in a wide range of practical applications such as adsorption, catalysis, adsorption, and sensing fields. However, some limitations, like wide pore size distribution, may limit their further applications, especially for adsorption. Here, micro- and ultra-microporous frameworks (HBPBA-D and TBBPA-D) were designed and synthesized via Sonogashira–Hagihara coupling of six/eight-arm bromophenyl adamantane-based “knots” and alkynes-type “rod” monomers. The BET surface area and pore size distribution of these frameworks were in the region of 395–488 m2 g−1, 0.9–1.1 and 0.42 nm, respectively. The as-made prepared frameworks also showed good chemical ability and high thermal stability up to 350 °C, and at 800 °C only 30% mass loss was observed. Their adsorption capacities for small gas molecules such as CO2 and CH4 was 8.9–9.0 wt % and 1.43–1.63 wt % at 273 K/1 bar, and for the toxic organic vapors n-hexane and benzene, 104–172 mg g−1 and 144–272 mg g−1 at 298 K/0.8 bar, respectively. These are comparable to many porous polymers with higher BET specific surface areas or after functionalization. These properties make the resulting frameworks efficient absorbent alternatives for small gas or toxic vapor capture, especially in harsh environments.
The proton exchange membrane electrolysis cell (PEMEC) has attracted considerable attention for large-scale and efficient hydrogen production because of its high current density, high hydrogen purity and fast dynamic response. Flow field distributions and water and thermal management characteristics of a PEMEC are vital for electrolytic cell structure and the determination of operating condition. A three-dimensional, non-isothermal, electrochemical model of a PEMEC was established in this manuscript. The flow field distribution and water and thermal management of the PEMEC are discussed. The corresponding results showed that the pressure of the flow channel decreased diagonally from the inlet to the outlet, and the pressure and velocity distribution exhibited a downward opening shape of a parabola. At the same inlet flow rate, when the voltage was 1.6 V, the oxygen generation rate was 15.74 mol/(cm2·s), and when the voltage was 2.2 V, the oxygen generation rate was 332.05 mol/(cm2·s); due to the change in the oxygen production rate, the pressure difference at 2.2 V was 2.5 times than that at 1.6 V. When the stoichiometric number was less than two, the average temperature of the catalyst layer (CL) decreased rapidly with the increase in the water flow rate. When the voltage decreased to 2.1 V, the current density came to the highest value when the stoichiometric number was 0.7, then the current density decreased with an increase in the stoichiometric number. When stoichiometric numbers were higher than five, the surface temperature and current density remained basically stable with the increase in the water flow rate, and the water and thermal management and electrolysis characteristics performed better. The research results could optimize the water supply of electrolysis cells. According to the velocity distribution law of the flow field, the water and thermal management performance of the PEMEC could be estimated, further promoting safety and reliability.