Open Access

ARTICLE

Advanced Poly(Lactic Acid)/Thermoplastic Polyurethane Blend-Based Nanocomposites with Carbon Nanotubes and Graphene Nanoplatelets for Shape Memory

Nayara Koba de Moura Morgado, Guilherme Ferreira de Melo Morgado, Erick Gabriel Ribeiro dos Anjos, Fabio Roberto Passador^*

Department of Science and Technology, Polymer and Biopolymer Technology Laboratory (TecPBio), Federal University of São Paulo (UNIFESP), 330 Talim St, São José dos Campos, 12231-280, SP, Brazil

* Corresponding Author: Fabio Roberto Passador. Email:

Journal of Polymer Materials 2025, 42(1), 95-110. https://doi.org/10.32604/jpm.2025.059364

Received 05 October 2024; Accepted 17 January 2025; Issue published 27 March 2025

Abstract

The continuous improvement in patient care and recovery is driving the development of innovative materials for medical applications. Medical sutures, essential for securing implants and closing deep wounds, have evolved to incorporate smart materials capable of responding to various stimuli. This study explores the potential of thermoresponsive sutures, made from shape memory materials, that contract upon heating to bring loose stitches closer together, promoting optimal wound closure. We developed nanocomposites based on a blend of poly(lactic acid) (PLA) and thermoplastic polyurethane (TPU)—biopolymers that inherently exhibit shape memory—enhanced with carbon nanotubes (CNT) and graphene nanoplatelets (GN) to improve mechanical performance. PLA/TPU (50/50) nanocomposites were prepared with 1 and 2 wt% GN, as well as hybrid formulations combining 1 wt% CNT with 1 or 2 wt% GN, using a twin-screw extrusion process to form filaments. These filaments were characterized through differential scanning calorimetry (DSC), field emission gun scanning electron microscopy (FEG-SEM), tensile testing, and shape memory assessments. While the PLA/TPU blend is immiscible, TPU enhances the crystallinity (X_c) of the PLA phase, further increased by the addition of CNT and GN. FEG-SEM images indicate CNTs primarily in the PLA phase and GN in the TPU phase. PLA/TPU with 1 or 2 wt% GN showed the highest potential for suture applications, with a high elastic modulus (~1000 MPa), significant strain at break (~10%), and effective shape recovery (~20% at 55°C for 30 min). These findings suggest that these nanocomposites can enhance suture performance with controlled shape recovery that is suitable for medical use.

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Keywords

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