Supramolecular Approach for Efficient Processing of Polylactide/Starch Nanocomposites

Development of Stereocomplex Polylactide Nanocomposites as an Advanced Class of Biomaterials-A Review

This review paper analyzes the development of advanced class polylactide (PLA) materials through a combination of stereocomplexation and nanocomposites approaches. The similarities in these approaches provide the opportunity to generate an advanced stereocomplex PLA nanocomposite (stereo-nano PLA) material with various beneficial properties. As a potential "green" polymer with tunable characteristics (e.g., modifiable molecular structure and organic-inorganic miscibility), stereo-nano PLA could be used for various advanced applications. The molecular structure modification of PLA homopolymers and nanoparticles in stereo-nano PLA materials enables us to encounter stereocomplexation and nanocomposites constraints. The hydrogen bonding of D- and L-lactide fragments aids in the formation of stereococomplex crystallites, while the hetero-nucleation capabilities of nanofillers result in a synergism that improves the physical, thermal, and mechanical properties of materials, including stereocomplex memory (melt stability) and nanoparticle dispersion. The special properties of selected nanoparticles also allow the production of stereo-nano PLA materials with distinctive characteristics, such as electrical conductivity, anti-inflammatory, and anti-bacterial properties. The D- and L-lactide chains in PLA copolymers provide self-assembly capabilities to form stable nanocarrier micelles for encapsulating nanoparticles. This development of advanced stereo-nano PLA with biodegradability, biocompatibility, and tunability properties shows potential for use in wider and advanced applications as a high-performance material, in engineering field, electronic, medical device, biomedical, diagnosis, and therapeutic applications.

High-Strength, Low-Permeable, and Light-Protective Nanocomposite Films Based on a Hybrid Nanopigment and Biodegradable PLA for Food Packaging Applications

Herein, a multifunctional filler, a dye (organic)-clay (inorganic) hybrid nanopigment (DCNP), was embedded into polylactic acid (PLA) to fabricate a colored biodegradable/biocompatible film, which is explored as a high thermomechanical resistant as well as a superior light and mass transport barrier for food packaging applications. In this respect, the DCNP was synthesized through a wet chemical process with a reaction yield of 76% and incorporated into a PLA matrix at various concentrations using a solution casting method. The morphological characterizations revealed partially intercalated/exfoliated structure for PLA-DCNP films. The samples filled with DCNP showed up to 20% and 12 °C improvements in storage modulus (E') and glass transition temperature (T g), respectively, compared to those with neat PLA. Incorporation of a small amount of DCNP into the PLA matrix significantly declined the water vapor and gas permeability of PLA by 36 and 54%, respectively. The optical property investigations indicated remarkable color characteristics and light protection performance of the samples containing DCNP. The results also showed better performance of the PLA-DCNP film compared to that of the PLA-Cloisite 20A sample at an identical filler loading. In conclusion, the desirable properties of the resulting films highlighted the potential application of such nanocomposite films as a promising option for food packaging materials.

Dopamine-Mediated Pre-Crosslinked Cellulose/Polyurethane Block Elastomer for the Preparation of Robust Biocomposites

The development of micro- and nanofibril cellulose to improve strength while reducing the side effects of toughness and water resistance can benefit integrated polymer performance. Inspired by the interior microstructure of mussel byssus, this paper proposed an efficient means of generating an active block microfibrillated cellulose/polyurethane elastomer using an epoxy monomer as a pre-crosslinked agent with the addition of a poly(dopamine) layer. The block elastomer served as a multifunctional crosslinker, constructing a covalent network and interfacial hydrogen bonding that interlinked the elastomer with a soy protein isolate (SPI) matrix. Compared with the pristine SPI film, the introduction of the block elastomer induced remarkable improvements in tensile strength and toughness (146.7 and 102.1%, respectively). Additionally, the block elastomer was employed to further estimate its reinforcing effect in SPI resin modification, which also exhibited favorable water resistance and adhesion performance. This strategy may provide a new approach for constructing superior elastomers to reinforce applicable biomass composites.