One-Pot, Solvent- and Catalyst-Free Synthesis of Polyphosphoramide as an Eco-Benign and Effective Flame Retardant for Poly(lactic acid)

Abstract

Despite many merits, biobased and biodegradable poly(lactic acid) (PLA) suffers from inherently high flammability, significantly impeding its practical applications in the areas of packaging, fibers, electric and electronics, etc. Phosphoramidesbased flame retardants have demonstrated exceptional flame retardancy in PLA only at very low loading levels. Unfortunately, exiting synthetic processes of phosphoramides often involve the use of a huge amount of organic solvents, presenting a potential threat to the ecosystem and human beings, in addition to high production costs. Herein, we report a one-pot, solvent-and catalyst-free, and green approach for the synthesis of a polyphosphoramide (DM-H) via two-step polycondensation between dimethyl methylphosphonate (DMMP) and 1,6-hexanediamine (HDA). As-synthesized DM-H exhibits exceptional flame-retardant efficiency in the PLA while preserving the mechanical properties of the PLA. The addition of only 2 wt % DM-H enables the PLA to achieve a desirable V-0 rating during vertical burning tests and a high limited oxygen index (LOI) value of 29.7%, because the DM-H can act both in the gas and condensed phases. Moreover, the tensile strength is of 59.7 MPa comparable to 62.1 MPa of the bulk PLA. This work offers an innovative and green approach for the synthesis of polyphosphoramides to create high-performance sustainable PLA materials with balanced flame retardancy and mechanical performances.

Nanocomposites Materials of PLA Reinforced with Nanoclays Using a Masterbatch Technology: A Study of the Mechanical Performance and Its Sustainability

“…The results are in concordance with the assumption in the previous test of a higher PLA degradation in NSF nanocomposites during the process. Similarities have been observed in the literature with surface-modified and organic reinforcements [32,45]. On the other hand, the T max is increased for all the materials and mainly for NSF nanocomposites.…”

Crystallization kinetics, aggregated structure and thermal stability of biodegradable poly(ethylene succinate) manipulated by a biocompatible layered metal phosphonate as an efficient nucleator

“…11), probably attributed to the hydrogen bond interaction. The residual yield of the PES/0.5%PPZn is the lowest at 600 °C, perhaps related to the catalytic effect of the P element of uniform dispersed PPZn on the pyrolysis of PES 65,66 …”

Effect of Cellulose and Cellulose Nanocrystal Contents on the Biodegradation, under Composting Conditions, of Hierarchical PLA Biocomposites

“…As a result of these research efforts, PLA is used today in a wide variety of applications [ 18 , 19 , 20 ]. In order to increase the competitiveness of biodegradable composite materials in such a way that they can displace conventional non-biodegradable materials in very dynamic and demanding sectors such as packaging, construction, textiles, and the automotive industry, a new generation of hierarchical or multiscale biodegradable composite materials (HBC) containing micro- and nanosized mechanical reinforcements are currently being developed [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”