Bio-inspired fabrication of composite membranes with ultrathin polymer–silica nanohybrid skin layer

Mineralized Supramolecular Hydrogels Bearing Tunable Thermo-Responsiveness

Although a variety of biomimetic mineralized materials have been created in the lab, the vast majority of these manmade examples lack response to external stimuli. Here, mineralized supramolecular hydrogels with on-demand thermo-responsiveness that are formed by a simple, physical crosslinking between amorphous CaCO₃ (ACC) nanoparticles and poly(acrylic acid) (PAA) are reported. Upon the addition of Na₂ CO₃ solution into a mixture composed of PAA and CaCl₂ , amorphous ACC nanoparticles are formed in situ and simultaneously crosslinked by PAA chains, giving rise to the mineralized hydrogels. Interestingly, upon tuning the content of the formed ACC, hydrogels with different types of thermo-responsiveness can be easily obtained, and the transparencies of the resulting hydrogels are dramatically changed during the temperature-driven phase transitions. As an application, these thermo-responsive mineralized hydrogels are used to control the exposure of UV light, which is successfully applied to switch fluorescent signals in response to temperature.

Crystalline and Spherulitic Morphology of Polymers Crystallized in Confined Systems

Due to the effects of microphase separation and physical dimensions, confinement widely exists in the multi-component polymer systems (e.g., polymer blends, copolymers) and the polymers having nanoscale dimensions, such as thin films and nanofibers. Semicrystalline polymers usually show different crystallization kinetics, crystalline structure and morphology from the bulk when they are confined in the nanoscale environments; this may dramatically influence the physical performances of the resulting materials. Therefore, investigations on the crystalline and spherulitic morphology of semicrystalline polymers in confined systems are essential from both scientific and technological viewpoints; significant progresses have been achieved in this field in recent years. In this article, we will review the recent research progresses on the crystalline and spherulitic morphology of polymers crystallized in the nanoscale confined environments. According to the types of confined systems, crystalline, spherulitic morphology and morphological evolution of semicrystalline polymers in the ultrathin films, miscible polymer blends and block copolymers will be summarized and reviewed.

A review on bisphenol A occurrences, health effects and treatment process via membrane technology for drinking water

Massive utilization of bisphenol A (BPA) in the industrial production of polycarbonate plastics has led to the occurrence of this compound (at μg/L to ng/L level) in the water treatment plant. Nowadays, the presence of BPA in drinking water sources is a major concern among society because BPA is one of the endocrine disruption compounds (EDCs) that can cause hazard to human health even at extremely low concentration level. Parallel to these issues, membrane technology has emerged as the most feasible treatment process to eliminate this recalcitrant contaminant via physical separation mechanism. This paper reviews the occurrences and effects of BPA toward living organisms as well as the application of membrane technology for their removal in water treatment plant. The potential applications of using polymeric membranes for BPA removal are also discussed. Literature revealed that modifying membrane surface using blending approach is the simple yet effective method to improve membrane properties with respect to BPA removal without compromising water permeability. The regeneration process helps in maintaining the performances of membrane at desired level. The application of large-scale membrane process in treatment plant shows the feasibility of the technology for removing BPA and possible future prospect in water treatment process.

Efficient desulfurization by polymer-inorganic nanocomposite membranes fabricated in reverse microemulsion

The sulfur in gasoline will convert to SO(2) after combustion under high temperature, which adversely affects human health and the environment. Membrane technique in particular pervaporation offers a number of potential advantages over conventional FCC gasoline desulfurization processes. The present study focuses on the performance enhancement of PDMS membrane by incorporating silica nanoparticles. Specifically, silica nanoparticles formed by the catalysis and templating of protamine in w/o reverse microemulsion are in situ embedded into PDMS bulk matrix, endowing the resultant oleophilic nanocomposite membranes with appropriate free volume properties and superior separation performance. Through the rational manipulation of biomimetic mineralization at water-oil interface, silica particles with uniform size are acquired. Following this protocol, by introducing organic PDMS oligomers into the oil phase, PDMS-SiO(2) nanocomposite membranes are prepared in a facile way. The resultant nanocomposite membranes display superior permeability and permselectivity in the pervaporative desulfurization using thiophene/n-octane binary mixture as model gasoline, for example, under the condition of 500 ppm sulfur in feed (40 L/h) at 30°C, an enrichment factor of 4.83-5.82 with a normalized permeation rate of 6.61-10.76 × 10(-5)kgm/m(2)h is acquired.