Nanocomposite Materials with Poly(l-lactic Acid) and Transition-Metal Dichalcogenide Nanosheets 2D-TMDCs WS2.

Mohammed Naffakh,Ana M García,Miriam Fernández,Diego A Moreno,Peter S Shuttleworth

doi:10.3390/polym12112699

Abstract

Layered transition-metal dichalcogenides (TMDCs) based on tungsten disulfide nanosheets (2D-WS2) were introduced via melt processing into poly(l-lactic acid) (PLLA) to generate PLLA/2D-WS2 nanocomposite materials. The effects of the 2D-WS2 on the morphology, crystallization, and biodegradation behavior of PLLA were investigated. In particular, the non-isothermal melt-crystallization of neat PLLA and PLLA/2D-WS2 nanocomposites were analyzed in detail by varying both the cooling rate and 2D-WS2 loading. The kinetic parameters of PLLA chain crystallization are successfully described using the Liu model. It was found that the PLLA crystallization rate was reduced with 2D-WS2 incorporation, while the crystallization mechanism and crystal structure of PLLA remained unchanged in spite of nanoparticle loading. This was due to the PLLA chains not being able to easily adsorb on the WS2 nanosheets, hindering crystal growth. In addition, from surface morphology analysis, it was observed that the addition of 2D-WS2 facilitated the enzymatic degradation of poorly biodegradable PLLA using a promising strain of actinobacteria, Lentzea waywayandensis. The identification of more suitable enzymes to break down PLLA nanocomposites will open up new avenues of investigation and development, and it will also lead to more environmentally friendly, safer, and economic routes for bioplastic waste management.

Highlights

IntroductionPoly(l-lactic acid) (PLLA) is a highly versatile, biodegradable, aliphatic polyester derived from
Poly(l-lactic acid) (PLLA) is a highly versatile, biodegradable, aliphatic polyester derived from100% renewable resources, such as corn and sugar beets
The aim of the current study is to demonstrate the advantages of using 2D-WS2 as a suitable nano-reinforcement to enhance poly(l-lactic acid) (PLLA) performance

Summary

Introduction

Poly(l-lactic acid) (PLLA) is a highly versatile, biodegradable, aliphatic polyester derived from. 100% renewable resources, such as corn and sugar beets This bioplastic offers great promise in a wide range of environmental and biomedical applications due to its favorable biodegradability, renewability, reasonably good mechanical properties, and versatile fabrication methods [1,2,3]. PLLA and its degradation products, namely H2 O and CO2 , are neither toxic nor carcinogenic to the human body, making it an excellent material for biomedical applications including sutures, clips, and drug delivery systems (DDS). As an emerging 2D layered nanomaterial, it has been recently reported that monolayer MoS2 with high surface area, superb thermal stability, and excellent mechanical properties [7] exhibits great potential as a reinforcement agent for polymers [8,9]. It has been shown that the 2D-TMDCs can potentially improve the polymeric materials mechanical and barrier properties, whilst not effecting their electrical insulation properties (e.g., polyurethane (PU) [8], polypropylene (PP) [10], poly(vinyl alcohol) (PVA) [11]

Objectives

Results

Conclusion