Jihong Sun

Hollow Carbon Spheres with Abundant Micropores for Enhanced CO2 Adsorption

The interest in the design and controllable fabrication of hollow carbon spheres (HCSs) emanates from their tremendous potential applications in adsorption, energy conversion and storage, and catalysis. However, the effective synthesis of uniform HCSs with high surface area and abundant micropores remains a challenge. In this work, HCSs with tunable microporous shells were rationally synthesized via the hard-template method using resorcinol (R) and formaldehyde (F) as a carbon precursor. HCSs with a very high surface area (1369 m2/g) and abundant micropores (0.53 cm3/g) can be obtained with the assistance of additional inorganic silanes (TEOS) simultaneously with the carbon source (RF). Interestingly, the extra-abundant micropores showed favorable adsorption for CO2, resulting in a 1.5 times increase in the CO2 adsorption capacity compared to that of normal HCSs under the same conditions. Meanwhile, these HCSs hold potential for use in the separation of gases such as CO2 and N2.

Nanoassemblies constructed from bimodal mesoporous silica nanoparticles and surface-coated multilayer pH-responsive polymer for controlled delivery of ibuprofen:

The pH-sensitive poly(D-A) grafted amine-functionalized bimodal mesoporous silica (D-A/BMMs) was prepared by a facile method used as a drug delivery vehicle. They exhibited superior properties such as good dispersion in aqueous medium, high drug loading efficiency, improved stability and high drug release rates. Meanwhile, its structural features and performances in a controlled delivery of ibuprofen (IBU) were systematically investigated by using XRD, N2 adsorption and desorption, SEM, TEM, FT-IR, elemental analysis and TG techniques. The results demonstrated that the obtained nanocomposite presented a flexible control over drug release by controlling the grafting amount of D-A onto the mesopores surface of aminated BMMs. The cumulative percent release of IBU from D-A/BMMs was found to be much higher at pH 7.4 than at pH 2.0. The release rate was very slow in an acidic medium but became faster in a neutral medium, owing to hydrogen bonding in an acidic medium and electrostatic repulsion between negatively charged carboxyl groups in an alkaline medium.

pH-sensitive Performance of Dextran-Poly (acrylic acid) Copolymer and its Application in Controlled in vitro Release of Ibuprofen

ABSTRACT Dextran–poly(acrylic acid) copolymers (D-A) are prepared through copolymerizing of acrylic acid (AA) with dextran. Their structural properties and performances are characterized using various methods. The results indicate that the carboxyl groups of poly(acrylic acid) strongly interact with the proton acceptors of glucose units in dextran, and the effects of AA/dextran molar ratio on the pH sensitivity of obtained copolymers are remarkable. The D-A copolymer shows a smart pH response, specifically, shrinkage in a low pH medium and swelling at high pH. The potential application of D-A copolymer as a drug delivery matrix is explored using ibuprofen as a model drug. GRAPHICAL ABSTRACT

Influence of alternative cations distribution in AgxLi96-x-LSX on dehydration kinetics and its selective adsorption performance for N2 and O2

Adsorption characteristics of pure gases N2 and O2 on various silver exchanged low silica X-type (AgxLi96-x-LSX) zeolites were investigated. The equilibrium adsorption isotherms of N2 and O2 were measured at 273 and 298 K. Textual and structural properties of parent and resultant AgxLi96-x-LSX were characterized by XRD, BET surface area, and SEM techniques. Kinetics of their thermal dehydration were studied by exploiting thermogravimetric and differential data (TG-DTG) obtained at three heating rates (5, 10 and 15 K) using two model-free (Kissinger and Flynn-Wall-Ozawa) and one model fitting (Coats-Redfern) methods. Forty one mechanism functions were used to evaluate kinetic triplet (activation energy, frequency factor, and most probable mechanism/model) for different stages of dehydration. Results revealed that the impact of very small content of silver on the adsorption of N2 is pronounced and attributed to weak chemical bonds formed between N2 and Ag+ clusters due to strong adsorption of N2 at low pres...

P(NIPAM-co-AA) @BMMs with Mesoporous Silica Core and Controlled Copolymer Shell and its Fractal Characteristics for Dual pH- and Temperature- Responsive Performance of Ibuprofen Release

ABSTRACT A kind of core–shell hybrid composite (P@BMMs) as a drug carrier was prepared through seed polymerization method, in which, biomodal mesoporous materials (BMMs) as core and copolymer poly(N-isopropylacryl-acrylamide)-co-poly(acrylicacid) [P(NIPAM-co-AA)] with pH- and temperature-responsive characteristics as shell. Its structural features and textural parameters were characterized using various techniques. The kinetic and thermodynamic evaluation demonstrated the existence of hydrogen bond interaction between IBU and P(NIPAM-co-AA)-coated surfaces. Meanwhile, the smart thermo/pH-responsive properties of ibuprofen (IBU) release could be regulated through adjusting coated amount of copolymer. Specially, the responsive properties of P@BMMs were traced by small-angle X-ray scattering technique, suggesting the surface roughness and structural irregularities. GRAPHICAL ABSTRACT

Regulating dual temperature- and pH-responsibility constructed from core-shell mesoporous hybrid silica (P(NIPAM-co-AA)@BMMs) via adjusting AA incorporation onto NIPAM

Abstract The mesoporous hybrid silicas (P@BMMs) with core-shell structure were successfully synthesized via seed polymerization method using bimodal mesoporous silica materials (BMMs) as core and dual pH- and temperature-responsive poly(N-isopropylacryl-acrylamide)-co-poly(acrylic acid) (P(NIPAM-co-AA)) copolymer as shell. Meanwhile, the obtained P@BMMs were physicochemically and morphologically characterized via X-ray diffraction, N2 adsorption-desorption isotherms, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, ultraviolet visible diffused reflection spectrum, small angle X-ray scattering (SAXS), dynamic light scattering, and thermogravimetric analysis techniques. The results indicated that P(NIPAM-co-AA) was successfully coated onto the mesoporous surface of used BMMs, while the uniform mesoporous structure of obtained P@BMMs was still preserved. Using ibuprofen (IBU) as a model drug, the influence of the P(NIPAM-co-AA) shell on the release kinetics of IBU was explored, and its performances elucidated that the P@BMMs nanoparticles presented an apparent thermo/pH-responsive properties, which could be regulated via adjusting mass ratio of AA to NIPAM, and their IBU-release kinetic profiles were favorable to Korsmeyer-Peppas model. Specially, SAXS patterns were employed to evaluate the fractal evolution of P@BMMs along with releasing time, showing the decline tendency for mass fractal value from 2.89 to 2.56 during the release time of 0.25–24 h. Graphical Abstract

Bipyridine-Proline Grafted Silicas with Different Mesopore Structures: Their Catalytic Performance in Asymmetric Aldol Reaction and Structure Effect

A series of immobilized bipyridine-proline based on mesoporous silica with different structures were synthesized via grafting followed by coordination method. All catalysts were used in asymmetric aldol reaction of cyclohexanone with 4-nitrobenzaldehyde, and their catalytic performance including activities and stabilities have been investigated. The results indicated that the pore structure, morphology, and even the particle dispersity all showed the effects on the catalytic performance of immobilized catalysts.Graphical Abstract