Many chemical and biomedical systems require delivery and controlled release of small molecules, which cannot be achieved by conventional polyelectrolyte-based layer-by-layer capsules. This work proposes an innovative hybrid microcapsule by incorporating in situ formed silica nanoparticles within or on the shell. The influence of various experimental conditions on the stability, mechanical strength and morphology of capsules w as investigated, and characterised by SEM, TEM, XRD, EDX and FTIR. The multifunctional capabilities of formed capsules were examined by encapsulating a small molecule Rhodamine B (Rh-B), which could be further released by an ultrasonic trigger. The results show that in situ formed SiO2 nanoparticles through hydrolysis greatly reduced the permeability of the shell yet with increased mechanical strength and ultrasound response. SiO 2 nanoparticles were shown to be distributed on the surface or inside polyelectrolyte shell, acting as supports for free -standing capsules in both liquid and dry environment. Rapid Rh-B molecules release and the fragmentation of the capsule shells were observed under 50W ultrasound irradiation for a few seconds. Such innovative capsules with capability of small molecule encapsulation and high ultrasound sensitivity could be promising for many applications where pulse release of small molecules is required.

This work aims to improve the rheological properties of partially hydrolysed polyacrylamide (HPAM) for enhanced oil recovery by using SiO 2 nanoparticles (NPs).Novel aqueous HAPM based SiO 2 nanocomposites were formulated and their rheological properties were investigated under different salinities, temperature and aging time. The results show that the inclusion of silica NPs improved significantly the viscosity and viscoelastic properties of HPAM especially under high temperature and high salinities. The NP/HPAM hybrid showed an impressive thermal stability at T= 80 ºCafter 12 days, and the viscosity reached ~5 times of that HPAM at 0.8w% NP loading. The FT-IR spectra data confirmed that the formation of hydrogen bond between the carbonyl groups in HPAM and the silanol functionalities on the surface of silica NPs, which attributed to the improved performance. The oscillation test indicated that seeding SiO 2 remarkably facilitated the cross links among polymer molecules and made the hybrids more elastically dominant. For a given HPAM concentration, it was observed that there was acritical NP concentration (CNC)which many indicating the absorption status of SiO 2 NPsonto HPAM, and the salinity also affected the viscosity value.

Electrochemically active covalent organic frameworks (COFs) are promising electrode materials for Li-ion batteries. However, improving the specific capacities of COF-based electrodes requires materials with increased conductivity and a higher concentration of redox-active groups. Here, we designed a series of pyrene-4,5,9,10-tetraone COF (PT-COF) and carbon nanotube (CNT) composites (denoted as PT-COFX, where X = 10, 30, and 50 wt % of CNT) to address these challenges. Among the composites, PT-COF50 achieved a capacity of up to 280 mAh g –1 as normalized to the active COF material at a current density of 200 mA g –1 , which is the highest capacity reported for a COF-based composite cathode electrode to date. Furthermore, PT-COF50 exhibited excellent rate performance, delivering a capacity of 229 mAh g –1 at 5000 mA g –1 (18.5C). Using operando Raman microscopy the reversible transformation of the redox-active carbonyl groups of PT-COF was determined, which rationalizes an overall 4 e – /4 Li + redox process per pyrene-4,5,9,10-tetraone unit, accounting for its superior performance as a Li-ion battery electrode.

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Microcapsules that can be efficiently loaded with small molecules and effectively released at the target area through the degradation of the capsule shells hold great potential for treating diseases. Traditional biodegradable polyelectrolyte (PE) capsules can be degraded by cells and eliminated from the body but fail to encapsulate drugs with small molecular weight. Here, we report a poly-l-arginine hydrochloride (PARG)/dextran sulfate sodium salt (DEXS)/silica (SiO2) composite capsule that can be destructed in cells and of which the in situ formed inorganic SiO2 enables loading of small model molecules, Rhodamine B (Rh-B). The composite capsules were fabricated based on the layer-by-layer (LbL) technique and the hydrolysis of tetraethoxysilane (TEOS). Capsules composed of nondegradable PEs and SiO2, polyllamine hydrochloride (PAH)/poly(sodium 4-styrenesulfonate) (PSS)/silica (the control sample), were prepared and briefly compared with the degradable composite capsules. An intracellular degradation study of both types of composite capsules revealed that PARG/DEXS/silica capsules were degraded into fragments and lead to the release of model molecules in a relatively short time (2 h), while the structure of PAH/PSS/silica capsules remained intact even after 3 days incubation with B50 cells. Such results indicated that the polymer components played a significant role in the degradability of the SiO2. Specifically, PAH/PSS scaffolds blocked the degradation of SiO2. For PARG/DEXS/silica capsules, we proposed the effects of both hydrolytic degradation of amorphous silica and enzymatic degradation of PARG/DEXS polymers as a cell degradation mechanism. All the results demonstrated a new type of functional composite microcapsule with low permeability, good biocompatibility, and biodegradability for potential medical applications.

low specific capacity of 73 mAh g −1 at 500 mA g −1 in a Li-ion cell. However, the electrochemical performance was greatly enhanced by forming the tube-type core-shell structure of the composites (DAPQ-COFX). Using this approach, we achieved specific capacities of up to 162 mAh g −1 at 500 mA g −1 . By varying the composition of the DAPQ-COFX composite, it was found that DAPQ-COF50, which contained 50 wt% of CNT, exhibited the highest utilization of the redox-active sites (95%). Notably, the DAPQ-COF50 composite presents the best rate performance in COF-based electrode materials reported so far, facilitating ultrafast charge/discharge rates as high as 50 A g −1 -this means that the device can be fully charged in just 11 s.

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Designing and fabricating multifunctional microcapsules are of considerable interest to both academic and industrial research aspects. This work reports an innovative approach to fabricate composite capsules with high UV and ultrasound responsive functionalities that can be used as external triggers for controlled release, yet with enhanced mechanical strength that can make them survive in harsh environment. Needle-like TiO 2 nanoparticles (NPs) were produced in situ into layer-by-layer (LbL) polyelectrolyte (PE) shells through the hydrolysis of titanium butoxide (TIBO). These rigid TiO 2 NPs yielded the formed capsules with an excellent mechanical strength, showing a free standing structure. A possible mechanism is proposed for their special morphology formation of the TiO 2 NPs and their reinforce effects. Synergistically, their response to UV and ultrasound was visualized via SEM, with results showing an irreversible shell rapture upon exposure to either the UV or ultrasound irradiation. As expected, the release studies revealed that the dextran release from the TiO2/PE capsules was both UV-dependent and ultrasound-dependent. Besides, biocompatibility of the capsules with the incorporation of amorphous TiO 2 NPs was confirmed by MTT assay experiment. All of these evidences suggested a considerable potential medicine application of the TiO 2 /PE capsules for controlled drug delivery.