Modified Starch as a Filter Controller in Water-Based Drilling Fluids.

Herein, the effectiveness of an itaconic acid (IA) graft copolymer on native corn starch (NCS) as a filter control agent in fresh water-based drilling fluids (WBDFs) was evaluated. The copolymer (S--IA_APS) was synthesized by conventional radical dispersion polymerization using the redox initiation system (NH)SO/NaHSO. The modification of the starches was verified by volumetry, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM).

Environmentally Friendly Fertilizers Based on Starch Superabsorbents.

Superabsorbents starches (SASs) were synthesized and characterized starting from native corn starch, bitter cassava and sweet cassava by graft copolymerization with itaconic acid. Additionally, their swelling behavior was studied both in water and in buffer solutions with different pHs and saline solutions. Their applicability was tested as environmentally friendly fertilizers in the absorption and release of urea, potassium nitrate and ammonium nitrate at different concentrations of fertilizers.

Hydrogels based on oxidized starches from different botanical sources for release of fertilizers.

Herein, hydrogels based on starch from corn, sweet cassava and bitter cassava were prepared by a straightforward approach. The hydrogels were obtained by an oxidation process using the redox system KMnO/NaHSO which leads to the formation of carbonyl and carboxyl groups with minimum polymer hydrolysis. The resulting oxidized samples as well as the native starches were extensively characterized by scanning electron microscopy, thermogravimetric analysis and wide angle X-ray scattering, among others.

Removal of anionic and cationic dyes with bioadsorbent oxidized chitosans.

Different oxidized chitosans were prepared following various approaches, by thermo-acid oxidation or by using KMnO/NaHSO, (NH)SO/NaHSO and KCrO/NaHSO redox pairs added sequentially or simultaneously. All these reactions pursue the formation of carboxylic groups which enhance their capability to remove model cationic and anionic dyes such as methylene blue and methyl orange, respectively. The resulting oxidized chitosans were structurally and thermally characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy and thermogravimetry.

Amphiphilic polymers bearing gluconolactone moieties: synthesis and long side-chain crystalline behavior.

The synthesis and characterization of amphiphilic polymers bearing gluconolactone moieties has been described. In a first step, an unprotected glycomonomer 2-[({[4-(d-gluconamid-N-yl)butyl]amino}carbonyl)oxy]ethyl acrylate, HEAG, has been synthesized. Posterior, this glycomonomer has been copolymerized with methyl methacrylate at different compositions and the kinetic behavior has been also studied calculating the monomer reactivity ratios by Kelen-Tüdös extended equation.