Preparation of graphene reinforced poly(lactic acid) nanocompositesviasolution casting approach for packaging applications.

This article demonstrates the synthesis of lactic acid oligomer-grafted-chitosan (OLLA-g-CH), a nanoamphiphilic molecule, by in situ condensation polymerization and its effective use as a nanofiller for improvement in multiple properties of poly(lactic acid) (PLA) films, essential for stringent food packaging applications. Fourier transform infrared spectroscopy (FTIR) analysis shows the presence of amide-ester bond at 1539 cm(-1), which confirms the structural grafting of OLLA chains with chitosan molecules. This nanoamphiphilic OLLA-g-CH molecule act as surfactant containing hydrophilic chitosan head and hydrophobic OLLA tails with average size in the range of ∼2-4 nm. Prepared PLA/OLLA-g-CH bionanocomposite films appear with uniform dispersion of nanoamphiphilic OLLA-g-CH molecules with self-assembled micelles having size as low as ∼20 nm and as high as ∼150 nm with core-shell morphology in PLA matrix. This nanofiller is found very effective toward significant reduction in oxygen permeability (OP) by ∼10-fold due to the reduction in solubility of oxygen molecules and improvement in crystal nucleation density due to availability of nanonucleating sites. Ultimate tensile strength (UTS) of PLA/OLLA-g-CH bionanocomposite films are relatively comparable to that of PLA, however, elongation at break is improved significantly. The onset of thermal degradation of PLA/(OLLA-g-CH) films is also found comparable to that of PLA film. The glass transition temperature (Tg) of bionanocomposites is decreased by more than 18 °C with increase in OLLA-g-CH loading, which indicates the improved plasticization characteristics of PLA matrix. The crystallization kinetics suggest nonthree dimensional truncated spherical structures, which is controlled by the combination of thermal and athermal instantaneous nucleations. POM analysis suggested that the spherulite growth of PLA is improved significantly with the addition of OLLA-g-CH. The reduction in Tg of PLA with improvement in elongation at break and multifold reduction in oxygen permeability offers this bionanocomposite films, a promising candidate for stringent food packaging applications.

Synthetic, theoretical, and catalysis studies of a cationic functionalized N-heterocyclic carbene complex of silver, namely, is reported. Specifically, 1b was synthesized by the reaction of 1-isopropyl-3-(N-phenylacetamido)imidazolium chloride (1a) with Ag 2 O in 64 % yield; 1a was synthesized by the alkylation reaction of 1-isopropylimidazole with N-phenyl chloroacetamide in 90 % yield. The molecular structure of 1b was determined by X-ray diffraction studies and was found to be active for polymerization of L-lactide at elevated temperatures under solvent-free melt conditions to give polylactide of moderate molecular weight with narrow molecular weight distribution. Density functional theory studies of the cationic species 2b, derived from NHC silver complex 1b, were employed to obtain an understanding of the structure, bonding, and electronic features of the mole-

Synthesis, structure, and catalysis studies of two namely,, for the bulk ring-opening polymerization of L-lactide are reported. Specifically, gold complex 1c was obtained from silver complex 1b by the transmetalation reaction with (SMe 2 )AuCl. Silver complex 1b was synthesized by the treatment of 3-(N-tert-butylacetamido)-1-(2-hydroxycyclohexyl)imidazolium chloride (1a) with Ag 2 O. Compound 1a was synthesized directly from the reaction of N-tert-butyl-2-chloroacetamide, cyclohexene oxide, and imidazole. The

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In this study, we successfully demonstrate single-step industrially scalable reactive extrusion of polylactic acid (PLA)/ cellulose nanocrystal (CNC)-based cast films which leads to reduced necking, improved processability, melt strength, and rheological behavior. PLA chains grafted onto CNCs, formed cross-linked gel-like structures of high molecular weight (M w ≈ 150−245 kDa), with varying grafting efficiency (14%−67%) or gel-fraction yield (16%− 69%), depending on the type of compatibilizers used. The reactively processed films show reduction in both oxygen properties (20%− 65%) and water vapor barrier properties (27%−50%), along with improved thermomechanical properties. These films finds potential applications for the storage of oil-and dairy-based products, which show shelf lives of ∼5 months and ∼2 weeks, respectively, and are within the standard migration limits, as per the set legislations. Therefore, the present study provides a novel, easily processable extrusion-based approach for manufacturing sustainable PLA/ CNC-based green and eco-friendly films with improved recyclability, biodegradability, and nontoxicity for potential applications as food packages on a commercial scale.