Production of filled hydrogels by mechanochemically induced polymerization

Abstract

Silica nanoparticles functionalized with polyvinylpyrrolidone (PVP) were obtained by the grinding/ mechanical activation of quartz or nonfunctionalized silica nanoparticles in a stirred media mill in the presence of 1-vinyl-2-pyrrolidone, as proven by Fourier transform infrared spectroscopy. The polymer layer thickness formed on the silica nanoparticles after 8 h of mechanical activation in the absence of polymerization initiators amounted to about 10 nm, as derived from shear rheology. The silica nanoparticles functionalized with the hydrophilic PVP by mechanochemical polymerization reaction were used as fillers for hydrogels based on poly(hydroxyethyl methacrylate) (polyHEMA). The water absorption, release properties, and mechanical properties of the polyHEMA-silica composites were measured as functions of the filler content and particle size of the filler. PolyHEMA samples containing 20 wt % of the functionalized silica particles exhibited a higher maximum water absorption than the unfilled polymer; this showed that the hydrophilic interface between the filler and the matrix improved the water absorption. The release of methylene blue from the poly-HEMA-silica composites was governed by diffusion and was almost unaffected by the silica particles. The values for the storage modulus and loss modulus of the poly-HEMA-silica composites increased with growing filler content. For constant filler content, the storage modulus increased with decreasing particle diameter of the filler; this showed that the reinforcing effect increased with the interface between the filler particles and the matrix polymer.

Synthesis of a novel pH responsive phyllosilicate loaded polymeric hydrogel based on poly(acrylic acid-co-N-vinylpyrrolidone) and polyethylene glycol for drug delivery: modelling and kinetics study for the sustained release of an antibiotic drug

“…As a result, the swelling ratio decreased. 30 The functional groups of the polymer as well as the hydrophilic ller participates in water absorption, and the network structure of the gel lled with the hydrophilic llers took a much shorter time to reach saturation.…”

Root development under control of magnesium availability

“…Previous researches reported that Mg deprivation (20 g/m 3 ) for 12 d severely reduced the root biomass of bean (Phaseolus vulgatis) plants for accumulation of sugars and starch in leaves. 20,21 Damm et al (2011) 22 suggested that low Mg availability together with high K supply enhanced the root-shoot ratio prior to any visible sign of Mg deficiency symptoms in rice leaves. This may be connected with the event that under Mg deficiency, carbon is more likely to be assigned to the leaves instead of the root.…”

Effects of inorganic salts on biomass production, cell wall components, and bioethanol production inNicotiana tabacum

“…Niu et al (2014) reported that primary root elongation and lateral root formation in Arabidopsis were not influenced by low Mg 2+ but inhibited by high Mg 2+ after one-week period. Damm et al (2011) suggested that low Mg 2+ availability together with high K + supply enhanced the root-shoot ratio prior to any visible sign of Mg 2+ deficiency symptoms in rice leaves.…”