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Polymeric superabsorbent hydrogels are the kind of gels that are obtained by chemically synthesizing with hydrophilic polymers to form a 3D-network structure. These hydrogels have been extensively used in agriculture over the last two decades as an absorbent. The aim of this work is to use the polymeric hydrogel to increase the water holding properties of growing media such as soil and to develop a low cost system for monitoring. Two types of polymeric hydrogels were prepared and the swelling ratio was determined. A three times higher swelling ratio was observed at DMAA (90 wt%) than that of SMG (30 wt%) even though both samples have the same cross-linker (MBAA). In contrast to DMAA, SMG gel has a greater crystalline network structure as measured by mechanical and dynamic light scattering. Experimental results suggest that the DMAA based hydrogel is suitable for agriculture. A low cost, sensor based, monitoring system was developed that indicates the merit of the system. [ABSTRACT FROM AUTHOR]

Chemically cross-linked shape memory hydrogels were synthesized, and their physical properties were studied. The gels were made from a hydrophilic monomer, i.e ., N,N-dimethyl acrylamide (DMAA), and a hydrophobic monomer, i.e ., stearyl acrylate (SA). The properties were characterized by varying the concentration of the cross-linker methylene bisacrylamide (MBAA), whereas the concentrations of other chemical components were held constant. It was observed that the mechanical properties strongly depended on the cross-linker concentration. The cross-linked hydrogels showed improved toughness compared to the hydrogel counterparts without cross-linking. Thermal properties were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC spectra of dried samples exhibited a complex crystalline nature, while swollen samples showed homogeneous crystallinity. The experimental results of DSC and TGA suggested that there was no significant influence of MBAA concentration on the crystallinity and thermal properties of swollen SMG hydrogels. [ABSTRACT FROM AUTHOR]

The hydrogel with shape memory was synthesized and investigated for possible biomedical science applications. The mechanical and optical properties of the chemically cross-linked shape memory hydrogel prepared from N,N-dimethyl acrylamide (DMAAm) and a crystalline monomer (i.e., stearyl acrylate (SA)) with varying concentrations of DMAAm were studied. The elastic modulus depends on the hydrophobic crystalline components. The refractive index exhibits an inverse relationship with the degree of swelling. Due to the transparency, high refractive index and high mechanical strength, the experimental results indicate the potential for use in biomedical applications. [ABSTRACT FROM AUTHOR]