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Thermoreversible physical gels of poly(styrene- b-butadiene- b-styrene) (SBS), formed by the dissolution of the block copolymer in a mid-block-selective solvent (THF), have been studied and characterized with particular attention to their morphology and rheological behavior. The effects of the addition of silver (Ag) nanoparticles to the SBS matrix, on the behavior of the physical gels, were also studied. The external surface of the Ag nanoparticles has been modified by using as surfactant material, dodecanethiol, in order to achieve their confinement in just one block of the SBS block copolymer matrix. The results of this study show that the gel stability is not affected by the presence of Ag nanoparticles. In fact, the micellar domains of the nanocomposite gel based on SBS block copolymer and Ag nanoparticles has been obtained and the physical gel behavior have been confirmed by rheological analysis. [ABSTRACT FROM AUTHOR]

Nanotechnology can change the scenario of current tools minimizing the chemical inputs in plant protection. Here, novel poly( dl-lactide-co-glycolide acid) (PLGA) copolymer-based biopolymeric nanoparticles (NP) and cellulose nanocrystals (CNC) were evaluated as basic materials for their use as nanocarriers to develop innovative plant protection formulations. PLGA NP were synthesized and tested, and the effect of natural surfactants, such as starch and CNC, on the NP final properties was investigated. Moreover, CNC were evaluated as possible nanostructured formulation to be directly applied in plant protection treatment. The effect of both, PLGA NP and CNC, was investigated with respect to their influence on the survival of the causal agent of bacterial speck disease ( Pseudomonas syringae pv. tomato, Pst), on plant development and damages (phytotoxicity effects), on tomato plant. The proposed nanocarriers are able to cover, with a uniform distribution, the tomato vegetal surfaces without any damage and to allow a regular development of the tomato-treated plants. Moreover, starch-PLGA NP formulations resulted unsuitable for Pst survival and multiplication along the time on the tomato plants surface. A great potentiality comes up of these nanocarriers on plants to carry out and to release antimicrobial active ingredients useful in innovative and sustainable plant protection strategies. [ABSTRACT FROM AUTHOR]

The tensile properties and structure of silica-based polyurethane (PU) nanocomposites were parametrically studied as a function of silica type and weight concentration, polyol OH number, and mixing methods. The variation of the silica functionalization groups (from silanols to silazanes) had a relevant effect on dispersion. An elevated interparticle distance of the silica agglomerates improved substantially the tensile strength (from 44.3 to 82.8 MPa) and strain to failure (from 3.0 to 7.95) while maintaining elastic modulus (from 2.08 to 2.31 GPa) with respect to the neat PU matrix. Polyol’s with different OH numbers have shown to dramatically modify the silica dispersion degree by the modification of the stability of the colloidal dispersion. An increase of its value deteriorated dispersion and the tensile properties of the nanocomposites. The effect of three dispersion methods (ultrasonic dispersion, high shear mixing, and tip sonication) has shown to have a relative effect on the reduction of agglomerate size and the interparticle distance. High power sonication methods were more effective in reducing agglomerate size in contrast to shear methods. Classical theories of colloidal dispersion (Derjaguin, Landau, Verwey, and Overbeek) have been able to explain the correlation between the silica aggregation state and the final tensile properties of the nanocomposite. [ABSTRACT FROM AUTHOR]