Bioactive and Physico-Chemical Assessment of Innovative Poly(lactic acid)-Based Biocomposites Containing Sage, Coconut Oil, and Modified Nanoclay

An Overview of Potential Applications of Environmentally Friendly Hybrid Polymeric Materials

The applications of polymeric materials are being constantly reviewed and improved. In the present world, the word hybrid, and the general idea of combining two or more inherently different approaches, designs, and materials is gaining significant attention. The area of sustainable materials with a low environmental impact is also rapidly evolving with many new discoveries, including the use of materials of a natural origin and countless combinations thereof. This review tries to summarize the current state of knowledge about hybrid polymeric materials and their applications with special attention to the materials that can be considered "environmentally friendly". As the current application field is quite broad, the review was limited to the following topics: packaging, medical applications, sensors, water purification, and electromagnetic shielding. Furthermore, this review points out the new prospects and challenges for the use of the mentioned materials in terms of creating novel solutions with different nano and micro-materials of mostly natural and renewable origin.

Zero Waste Concept in Production of PLA Biocomposites Reinforced with Fibers Derived from Wild Plant (Spartium junceum L.) and Energy Crop (Sida hermaphrodita (L.) Rusby)

This research follows the principles of circular economy through the zero waste concept and cascade approach performed in two steps. Our paper focuses on the first step and explores the characteristics of developed biocomposite materials made from a biodegradable poly(lactic acid) polymer (PLA) reinforced with natural fibers isolated from the second generation of biomass (agricultural biomass and weeds). Two plants, Spartium junceum L. (SJL) and Sida hermaphrodita (SH), were applied. To enhance their mechanical, thermal, and antimicrobial properties, their modification was performed with environmentally friendly additives-linseed oil (LO), organo-modified montmorillonite nanoclay (MMT), milled cork (MC), and zinc oxide (ZnO). The results revealed that SH fibers exhibited 38.92% higher tensile strength than SJL fibers. Composites reinforced with SH fibers modified only with LO displayed a 27.33% increase in tensile strength compared to neat PLA. The addition of LO improved the thermal stability of both biocomposites by approximately 5-7 °C. Furthermore, the inclusion of MMT filler significantly reduced the flammability, lowering the heat release rate to 30.25%, and enabling the categorization of developed biocomposite in a group of flame retardants. In the second step, all waste streams generated during the fibers extraction process are repurposed into the production of solid biofuels (pellets, briquettes) or biogas (bio)methane.

Reverse Gradient Distributions of Drug and Polymer Molecules within Electrospun Core-Shell Nanofibers for Sustained Release

Core-shell nanostructures are powerful platforms for the development of novel nanoscale drug delivery systems with sustained drug release profiles. Coaxial electrospinning is facile and convenient for creating medicated core-shell nanostructures with elaborate designs with which the sustained-release behaviors of drug molecules can be intentionally adjusted. With resveratrol (RES) as a model for a poorly water-soluble drug and cellulose acetate (CA) and PVP as polymeric carriers, a brand-new electrospun core-shell nanostructure was fabricated in this study. The guest RES and the host CA molecules were designed to have a reverse gradient distribution within the core-shell nanostructures. Scanning electron microscope and transmission electron microscope evaluations verified that these nanofibers had linear morphologies, without beads or spindles, and an obvious core-shell double-chamber structure. The X-ray diffraction patterns and Fourier transform infrared spectroscopic results indicated that the involved components were highly compatible and presented in an amorphous molecular distribution state. In vitro dissolution tests verified that the new core-shell structures were able to prevent the initial burst release, extend the continuous-release time period, and reduce the negative tailing-off release effect, thus ensuring a better sustained-release profile than the traditional blended drug-loaded nanofibers. The mechanism underlying the influence of the new core-shell structure with an RES/CA reverse gradient distribution on the behaviors of RES release is proposed. Based on this proof-of-concept demonstration, a series of advanced functional nanomaterials can be similarly developed based on the gradient distributions of functional molecules within electrospun multi-chamber nanostructures.

A review of starch-based biocomposites reinforced with plant fibers

Renewable and biodegradable resources have gained increasing attention as promising alternatives to synthetic plastics. Among the diverse raw materials employed in bioplastics production, starch emerges as an attractive, low-cost, and largely available source. However, the inherent properties of starch-based materials often limit their utility across various applications, necessitating strategic modifications to enhance their performance. A common approach to boost these materials involves incorporating natural fillers into biopolymer matrices. Incorporating natural fibers within starch matrices enables the development of biocomposites with improved properties while retaining their renewable and biodegradable characteristics. This review briefly addresses fundamental aspects of starch structure, obtention, and processing, as well as the main pre-treatments of natural fibers and processing methods currently applied to produce starch-based composites. It also highlights the most recent advances in this field, elucidates the effect of the incorporation of fibers on the biocomposite properties, and discusses the critical parameters affecting the synergic combination between starch and fibers.