Polyacrylamide/sodium alginate modified montmorillonite (PAM/SA-MMT) superabsorbent composites were synthesized by free-radical polymerization under normal atmospheric conditions. They were characterized by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy (FTIR). Their water absorbency and methylene blue (MB) adsorption behaviors were studied. Compared with PAM/MMT composites, PAM/SA-MMT composites demonstrated greater water absorbency (863 g g 21 in distilled water and 101 g g 21 in 0.9 wt % NaCl solution) and higher adsorption capacity of 2639 mg g 21 for MB. The adsorption behaviors of the composites showed that the isotherms and adsorption kinetics were in good agreement with the Langmuir equation and pseudo-second-order equation, respectively. FTIR analysis suggested that the MB adsorption of PAM/SA-MMT composites via a mechanism combined electrostatic, H-bonding and hydrophobic interaction. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40013.

Polyacrylic acid/montmorillonite(MMT)/carboxymethylcellulose (CMC) superabsorbent nanocomposites were prepared by frontal polymerization (FP), an economic method characterized by low-energy consumption and short-reaction time. They were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The effects of reaction parameters on the front propagation and the water absorbency of the nanocomposites were investigated. Furthermore, the effects of the obtained products on soil water holding capacity and soil water stable macro-aggregates were studied. Compared with the control soil, soil mixed with the nanocomposites showed a significant increase (by 52.4%) in field water holding capacity. The incorporation small amounts of MMT effectively promoted the formation of soil water stable macro-aggregates, which increased by 76% as the addition of the MMT increased to 4 wt %. The samples obtained by FP showed much better performance in the formation of soil water stable macro-aggregates, salt resistance, and thermal stability than those obtained by conventional batch polymerization.

Poly(acrylic acid-co-acrylamide)/sodium carboxymethyl cellulose/vermiculite (VMT) superabsorbent polymers (SAPs) were prepared by frontal polymerization (FP), a kind of polymerization model characterized by short reaction times and low-energy consumption. The effects of VMT content and monomer ratios on frontal parameters and water absorbency were investigated. Due to the good heat insulation property of VMT, the propagating front still sustained at high VMT concentrations (over 30%). The preparation of SAPs with high VMT-loading via FP has advantages of low energy consumption and low materials prices, decreasing the cost of SAPs effectively. SAPs with slow-release fertilizer (SSRF) were obtained by embedding urea into their networks during the FP process. The addition of urea not only endows SAPs with slow release function of urea (more than 30 days in soil), but also increases their water absorbency (by 17.4%). The effects of obtained SSRF on tall fescue seeds germination and growth were studied. Compared with the control group, the germination rate and vigor index of tall fescue seeds applied SSRF with 10% urea increased by 17.5 and 80.2%, respectively. POLYM. ENG. SCI., 57:69-77, 2017.