Role of Mechanical Factors in Applications of Stimuli-Responsive Polymer Gels - Status and Prospects

Due to their unique characteristics such as multifold change of volume in response to minute change in the environment, resemblance of soft biological tissues, ability to operate in wet environments, and chemical tailorability, stimuli responsive gels represent a versatile and very promising class of materials for sensors, muscle-type actuators, biomedical applications, and autonomous intelligent structures. Success of these materials in practical applications largely depends on their ability to fulfill application-specific mechanical requirements. This article provides an overview of recent application-driven development of covalent polymer gels with special emphasis on the relevant mechanical factors and properties. A short account of mechanisms of gel swelling and mechanical characteristics of importance to stimuli-responsive gels is presented. The review highlights major barriers for wider application of these materials and discusses latest advances and potential future directions toward overcoming these barriers, including interpenetrating networks, homogeneous networks, nanocomposites, and nanofilamentary gels.

Preparation of an oil-absorptive gel containing a 4-t-butyl styrene–EPDM–divinyl benzene graft polymer by reactive processing

A new reactive processing method was developed to prepare tBS–EPDM–DVB gels, which provides an environmentally-friendly method to produce oil-absorptive gels.

An environmentally friendly method for the fabrication of reduced graphene oxide foam with a super oil absorption capacity

Three kinds of graphene oxide (GO) foams were fabricated using different freezing methods (unidirectional freezing drying (UDF), non-directional freezing drying, and air freezing drying), and the corresponding reduced graphene oxide (RGO) foams were prepared by their thermal reduction of those GO foams. These RGO foams were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The absorption process and the factors that influence the absorption capacity were investigated. The RGO foams are hydrophobic and showed extremely high absorbing abilities for organic liquids. The absorption capacity of the RGO foams made by UDF was higher than 100 g g(-1) for all the oils tested (gasoline, diesel oil, pump oil, lubricating oil and olive oil) and had the highest value of about 122 g g(-1) for olive oil. The oil absorption capacity of the GO foams was lower than that of the RGO foams, but for olive oil, the absorption capacity was still high than 70 g g(-1), which is higher than that of most oil absorbents.

Studies on Methacrylate-hydroethyl Methacrylate Oil-absorptive Fiber

A concept of potential crosslinker was introduced into the synthesizing process of highly oil-absorptive resin which is traditionally prepared by single chemical crosslinking. The resin was dissolved in DMAc and then span into fiber. The fiber was heated after spinning to obtain three-dimensional network structure. The effects of potential crosslinker content, crosslinked time and crosslinked temperature on the absorptive properties of fiber were studied. The structure of oil-absorptive fiber was analyzed by FTIR, DMA and SEM.

Synthesis and characterization of a highly absorptive resin using glow discharge electrolysis plasma

Background

A highly absorptive resin poly(butyl acrylate-co-styrene) was synthesized by the method of emulsion polymerization and initiated using glow discharge electrolysis plasma. The effects of the synthesis conditions were examined and discussed in detail. The synthesized resin was characterized by attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis.

Results

The results showed that the optimal conditions were as follows: discharge voltage 580 V, discharge time 11 min, polymerization temperature 90°C, ratio of water/monomer 4.0, and 3% of N,N-methylenebis(acrylamide).

Conclusion

Under the optimal conditions, the oil absorbency was 97 g/g for chloroform and 56 g/g for xylene. In addition, the kinetics of absorption for oil was investigated, and the results indicated that the absorption process seems to obey more the first-order rate model.