Hydrogels for biomedical applications.

Acrylic acid/acrylamide based hydrogels and its properties - A review

Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from PAA derivatives can be used to deliver drugs due to their stability and biocompatibility. PAA and its nanoconjugates could also be regarded as stimuli-responsive platforms that make them ideal for drug delivery and antimicrobial applications. These properties make PAA a good candidate for conventional and novel drug carrier systems. Here, we started with synthesis approaches, structure characteristics, and other architectures of PAA nanoplatforms. Then, different conjugations of PAA/nanostructures and their potential in various fields of nanomedicine such as antimicrobial, anticancer, imaging, biosensor, and tissue engineering were discussed. Finally, biocompatibility and challenges of PAA nanoplatforms were highlighted. This review will provide fundamental knowledge and current information connected to the PAA nanoplatforms and their applications in biological fields for a broad audience of researchers, engineers, and newcomers. In this light, PAA nanoplatforms could have great potential for the research and development of new nano vaccines and nano drugs in the future.

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Polyacrylic Acid Nanoplatforms: Antimicrobial, Tissue Engineering, and Cancer Theranostic Applications

Foamed materials are honeycomb-shaped structures bearing porous networks which exhibit considerable compressive strengths, and excellent efficiency for oil-water separation. The presence of spilled oils and solvents in wastewater intensifies with accumulation over the time later creating toxicity to the environment. The ever growing industrial demands precede contamination of water sources which later make it difficult in its eradication. The scientific community has spearheaded the research towards materials exhibiting high oil/-solvent absorption capacity, compression strength, and recycling ability for the effective removal of accumulated spilt oils and solvents from wastewater. Recently, foamed materials have gained wide focus for oil/-solvent recovery due to high absorption capacity rendered by 3D porous structure present in the foams. Carbon-based lightweight (density = 0.2–0.8 g/cm3) foam exhibiting compressive strength of 20 MPa, porosity of 93%, and hydrophobicity (water contact angle = 149o), has been reported for oil-water separation application. In this sense, present review provides an in-depth study on various foams capable of removing the spilt oil/solvents from wastewater and their mechanism, toxic effects on the environment, and the factors affecting oil/solvent absorption performance of the foams, for the effective oil/solvent recovery.

Foamed materials for oil-water separation

Superhydrophobic nanohybrid sponges for separation of oil/ water mixtures.

We proposed a novel strategy in the fabrication of biodegradable poly(acrylic acid-co-acrylamide)/poly(vinyl alcohol) (P(AAc-co-Am)/PVA) double network (DN) hydrogels with good mechanical and self-healing properties. In the DN hydrogel system, P(AAc-co-Am) polymers form a network through the ionic coordinates between –COO– and Fe3+ and hydrogen bonding between –COOH and –CONH2, while another network is fabricated by the complexation between PVA and borax. The influences of the composition on the rheological behaviors and mechanical properties of the synthesized DN hydrogels were investigated. The rheological measurements revealed that the viscoelasticity and stiffness of the P(AAc-co-Am)/PVA DN hydrogels increase as the acrylamide and Fe3+ concentrations increase. At 0.05 mmol of Fe3+ and 50% of acrylamide, tensile strength and elongation at break of P(AAc-co-Am)/PVA DN hydrogels could reach 329.5 KPa and 12.9 mm/mm, respectively. These properties arise from the dynamic reversible bonds existed in the P(AAc-co-Am)/PVA DN hydrogels. These reversible bonds also give good self-healing properties, and the maximum self-healing efficiency of P(AAc-co-Am)/PVA DN hydrogels is up to 96.4%. The degradation test of synthesized DN hydrogels was also conducted under simulated physiological conditions and the weight loss could reach 74% in the simulated intestinal fluid. According to the results presented here, the synthesized P(AAc-co-Am)/PVA DN hydrogels have a potential application prospect in various biomedical fields.

Biodegradable Poly(acrylic acid-co-acrylamide)/Poly(vinyl alcohol) Double Network Hydrogels with Tunable Mechanics and High Self-healing Performance.

In order to cope with the increasing oil spill accidents and the intentional discharge of oily wastewater, a new oil-adsorbing material with superhydrophobicity and reusability is needed. In this paper, waste plastic was used to fabricate an alveolate polystyrene (PS) foam to reduce secondary pollution. The PS foam was synthesized from a high internal phase Pickering emulsion (HIPPE) technique in a one-step process. The emulsion was stabilized by a co-Pickering system of Span 80 surfactant and SiO2 particles. To explain the super stability of the HIPPE, a novel model of the water-in-oil droplet was promoted. The obtained SiO2@PS foam exhibited a multi-order-porous structure, and displayed superhydrophobicity and superoleophilicity. It can selectively remove various oily contaminants from water with a high adsorption capacity of 20.4–58.1 g g−1 at a fast rate. The oil-adsorbed material can be reused by simple centrifugation, and no more than a 1% decline was obtained in the oil adsorption after 10 cycles. Therefore, the SiO2@PS foam has a great potential application in oily water treatment.

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Preparation of a porous superhydrophobic foam from waste plastic and its application for oil spill cleanup

In this paper, poly(styrene-divinylbenzene) foams were synthesized using a high internal phase emulsion (HIPE) technique with Span 80 and with 900 °C calcined oyster shell powder as a co-emulsifier, 2,2′-azobisisobutyronitrile (AIBN) as an initiator and deionized water as the dispersing phase. SEM images revealed that the materials possess a hierarchical porous structure of nano/micro size, which resulted in saturated oil adsorption in only half a minute. The dispersing phase amount was investigated for its effect on adsorption. The optimized foams have 24.8–58.3 g g−1 adsorbencies for several organic solvents, and they demonstrated superhydrophobicity and excellent oleophilicity with the water contact angle (WCA) even close to 149° and oil contact angle approaching 0°. Moreover, the foams displayed high oil retention under pressure. The adsorption–centrifugation cycling results indicated high repeatability of the recovered foams. All of these features predicted the potential applications of superhydrophobic foams in oil–water separation.

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Superhydrophobic foam prepared from high internal phase emulsion templates stabilised by oyster shell powder for oil–water separation

Oil spills cause serious environmental pollution and serious waste of resources, hydrophobic porous absorbent has been deemed as a simple, low-cost, efficient and environment-friendly in oil–water separation. In this paper, a facile emulsion template method was developed to fabricate an interconnected porous poly(DVB-MMA) sponge. A novel co-Pickering stabilization system of Span 80 and NiFe2O4 nanoparticles was applied to fabricate ultra-concentrated internal phase W/O emulsions. After further polymerization, the resulting sponge showed excellent adsorption selectivity due to superhydrophobicity and superlipophilicity. Also, the characterization results exhibited that the composite had superior thermal stability, low density, high porosity and flexible three-dimensional porous structure. Besides, waste PS plastic was introduced to enhance the structural integrity of composite, and the addition of NiFe2O4 provided the material with magnetic operability. High oil adsorption capacity (up to 44.3–101.0 g/g), high oil retention, fast adsorption rate and superior recyclability allowed the material to be used in the fields of oil–water separation and oil pollution treatment.

Facile fabrication of compressible, magnetic and superhydrophobic poly(DVB-MMA) sponge for high-efficiency oil–water separation

Super-hydrophobic porous absorbents are convenient, low-cost, efficient and environment-friendly materials in the treatment of oil spills. In this work, a simple Pickering emulsion template method was employed to fabricate an interconnected porous poly(DVB-LMA) sponge. A new co-Pickering stabilization system of Span 80 and NiFe2O4 nanoparticles was used to prepare ultra-concentrated internal phase water-in-oil (W/O) emulsions. After further polymerization, the resulting sponges were generated, which exhibited excellent adsorption selectivity due to the super-hydrophobicity and super-lipophilicity. Furthermore, the characterization results indicated that the composites had superior thermal stability, low density, high porosity and a flexible three-dimensional porous structure. Besides, the addition of nickel ferrite nanoparticles provided the materials with extra magnetic operability. High oil adsorption capacity (up to 36.9-84.2 g g-1), high oil retention, fast adsorption rate and superior reusability allowed the materials to be applied in the treatment of oily water.

Yu Chuanming

Papers

Biodegradable Poly(acrylic acid-co-acrylamide)/Poly(vinyl alcohol) Double Network Hydrogels with Tunable Mechanics and High Self-healing Performance.

Preparation of a porous superhydrophobic foam from waste plastic and its application for oil spill cleanup

Superhydrophobic foam prepared from high internal phase emulsion templates stabilised by oyster shell powder for oil–water separation

Facile fabrication of compressible, magnetic and superhydrophobic poly(DVB-MMA) sponge for high-efficiency oil–water separation

Fabrication of hydrophobic NiFe2O4@poly(DVB–LMA) sponge via a Pickering emulsion template method for oil/water separation