Fire-Resistant, Strong, and Green Polymer Nanocomposites Based on Poly(lactic acid) and Core–Shell Nanofibrous Flame Retardants

PLA has become a commodity polymer with wide applications in a number of fields. However, its high flammability with the tendency to flow in fire has limited its viability as a perfect replacement for the petrochemically-engineered plastics. Traditional flame retardants, which may be incorporated into PLA without severely degrading the mechanical properties, are the organo-halogen compounds. Meanwhile, these compounds tend to bioaccumulate and pose a risk to flora and fauna due to their restricted use. Research into PLA flame retardants has largely focused on organic and inorganic compounds for the past few years. Meanwhile, the renewed interest in the development of environmentally sustainable flame retardants (FRs) for PLA has increased significantly in a bid to maintain the integrity of the polymer. A review on the development of new flame retardants for PLA is presented herein. The focus is on metal oxides, phosphorus-based systems, 2D and 1D nanomaterials, hyperbranched polymers, and their combinations, which have been applied for flame retarding PLA are discussed. The paper also reviews briefly the correlation between FR loadings and efficiency for various FR systems, and their effects on processing and mechanical properties.

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Development of paclitaxel-loaded poly(lactic acid)/hydroxyapatite core–shell nanoparticles as a stimuli-responsive drug delivery system

Royal Society Open Science ◽

10.1098/rsos.202030 ◽

2021 ◽

Vol 8 (3) ◽

Author(s):

Sungho Lee ◽

Tatsuya Miyajima ◽

Ayae Sugawara-Narutaki ◽

Katsuya Kato ◽

Fukue Nagata

Keyword(s):

Drug Delivery ◽

Lactic Acid ◽

Delivery Systems ◽

Ph Sensitivity ◽

Poly Lactic Acid ◽

Core Shell ◽

Stimuli Responsive ◽

Shell Nanoparticles ◽

The Core ◽

Core Shell Nanoparticles

Biodegradable nanoparticles have been well studied as biocompatible delivery systems. Nanoparticles of less than 200 nm in size can facilitate the passive targeting of drugs to tumour tissues and their accumulation therein via the enhanced permeability and retention (EPR) effect. Recent studies have focused on stimuli-responsive drug delivery systems (DDS) for improving the effectiveness of chemotherapy; for example, pH-sensitive DDS depend on the weakly acidic and neutral extracellular pH of tumour and normal tissues, respectively. In our previous work, core–shell nanoparticles composed of the biodegradable polymer poly(lactic acid) (PLA) and the widely used inorganic biomaterial hydroxyapatite (HAp, which exhibits pH sensitivity) were prepared using a surfactant-free method. These PLA/HAp core–shell nanoparticles could load 750 wt% of a hydrophobic model drug. In this work, the properties of the PLA/HAp core–shell nanoparticles loaded with the anti-cancer drug paclitaxel (PTX) were thoroughly investigated in vitro . Because the PTX-containing nanoparticles were approximately 80 nm in size, they can be expected to facilitate efficient drug delivery via the EPR effect. The core–shell nanoparticles were cytotoxic towards cancer cells (4T1). This was due to the pH sensitivity of the HAp shell, which is stable in neutral conditions and dissolves in acidic conditions. The cytotoxic activity of the PTX-loaded nanoparticles was sustained for up to 48 h, which was suitable for tumour growth inhibition. These results suggest that the core–shell nanoparticles can be suitable drug carriers for various water-insoluble drugs.

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Expanding Poly(lactic acid) (PLA) and Polyhydroxyalkanoates (PHAs) Applications: A Review on Modifications and Effects

Polymers ◽

10.3390/polym13234271 ◽

2021 ◽

Vol 13 (23) ◽

pp. 4271

Author(s):

Ahmed Z. Naser ◽

Ibrahim Deiab ◽

Fantahun Defersha ◽

Sheng Yang

Keyword(s):

Lactic Acid ◽

Flame Retardants ◽

Driving Forces ◽

Impact Resistance ◽

High Price ◽

Poly Lactic Acid ◽

Waste Plastics ◽

Biobased Polymers ◽

Surgical Implants ◽

Recent Climate

The high price of petroleum, overconsumption of plastic products, recent climate change regulations, the lack of landfill spaces in addition to the ever-growing population are considered the driving forces for introducing sustainable biodegradable solutions for greener environment. Due to the harmful impact of petroleum waste plastics on human health, environment and ecosystems, societies have been moving towards the adoption of biodegradable natural based polymers whose conversion and consumption are environmentally friendly. Therefore, biodegradable biobased polymers such as poly(lactic acid) (PLA) and polyhydroxyalkanoates (PHAs) have gained a significant amount of attention in recent years. Nonetheless, some of the vital limitations to the broader use of these biopolymers are that they are less flexible and have less impact resistance when compared to petroleum-based plastics (e.g., polypropylene (PP), high-density polyethylene (HDPE) and polystyrene (PS)). Recent advances have shown that with appropriate modification methods—plasticizers and fillers, polymer blends and nanocomposites, such limitations of both polymers can be overcome. This work is meant to widen the applicability of both polymers by reviewing the available materials on these methods and their impacts with a focus on the mechanical properties. This literature investigation leads to the conclusion that both PLA and PHAs show strong candidacy in expanding their utilizations to potentially substitute petroleum-based plastics in various applications, including but not limited to, food, active packaging, surgical implants, dental, drug delivery, biomedical as well as antistatic and flame retardants applications.

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