Blending Ferulic Acid Derivatives and Polylactic Acid into Biobased and Transparent Elastomeric Materials with Shape Memory Properties

A Shape-Restorable hierarchical polymer membrane composite system for enhanced antibacterial and antiadhesive efficiency

Intelligent shape memory polymer can be potentially used in manufacturing implantable devices that enables a benign variation of implant dimensions with the external stimuli, thus effectively lowering insertion forces and evading associated risks. However, in surgical implantation, biomaterials-associated infection has imposed a huge burden to healthcare system that urgently requires an efficacious replacement of antibiotic usages. Preventing the initial attachment and harvesting a biocidal function upon native surfaces may be deemed as a preferable strategy to tackle the issues of bacterial infection. Herein, a functionalized polylactic acid (PLA) composite membrane assembled with graphene (GE, a widely used photothermal agent) was fabricated through a blending process and then polydimethylsiloxane utilized as binders to pack hydrophobic SiO2 tightly onto polymer surface (denoted as PLA-GE/SiO2). Such an active platform exhibited a moderate shape-memory performance upon near-infrared (NIR) light stimulation, which was feasible for programmed deformation and shape recovery. Particularly stirring was that PLA-GE/SiO2 exerted a pronounced bacteria-killing effect under NIR illumination, 99.9 % of E. coli and 99.8 % of S. aureus were effectively eradicated in a lean period of 5 min. Furthermore, the obtained composite membrane manifested excellent antiadhesive properties, resulting in a bacteria-repelling efficacy of up to 99 % for both E. coli and S. aureus species. These findings demonstrated the potential value of PLA-GE/SiO2 as a shape-restorable platform in "kill&repel" integration strategy, further expanding its applications for clinical anti-infective treatment.

Functionalized TMC and ε-CL elastomers with shape memory and self-healing properties

Introduction: Smart elastomers, which possess self-healing and shape memory capabilities, have immense potential in the field of biomedical applications. Polycarbonates and polyesters have gained widespread interest due to their remarkable biocompatibility over the last century. Nevertheless, the lack of functional versatility in conventional polyesters and polycarbonates means that they fall short of meeting the ever-evolving demands of the future. Methods: This paper introduced a new smart elastomer, named mPEG43-b-(PMBC-co-PCL)n, developed from polyester and polycarbonate blends, that possessed shape memory and self-heal capabilities via a physical crosslinking system. Results: The material demonstrated a significant tensile strength of 0.38 MPa and a tensile ratio of 1155.6%, highlighting its favorable mechanical properties. In addition, a conspicuous shape retrieval rate of 93% was showcased within 32.5 seconds at 37°C. Remarkably, the affected area could be repaired proficiently with no irritation experienced during 6h at room temperature, which was indicative of an admirable repair percentage of 87.6%. Furthermore, these features could be precisely modified by altering the proportion of MBC and ε-CL to suit individual constraints. Discussion: This innovative elastomer with exceptional shape memory and self-heal capabilities provides a solid basis and promising potential for the development of self-contracting intelligent surgical sutures in the biomedical field.

Effect of ferulic acid derivative concentration on the release kinetics, antioxidant capacity, and thermal behaviour of different polymeric films

Ferulic acid displays poor thermal resistance during extrusion and compression moulding, slow 2,2-diphenyl-1-picrylhydrazyl (DPPH) reaction kinetics, and undetected release from polylactide (PLA) and polyhydroxyalkanoates (PHA)-based films into polar media. Thus, in this study, a ferulic acid derivative Bis-O-dihydroferuloyl-1,4-butanediol (BDF) was used as an active additive (up to 40 w%) in PLA, poly(3-hydroxybutyrate) (PHB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrices to produce blends by extrusion. These blends were then used to prepare films by solvent casting. The BDF displayed good stability with 86-93% retention. The release kinetics in Food Simulant A revealed higher BDF release amounts (1.16-3.2%) for PHA-based films as compared to PLA. The BDF displayed faster DPPH reaction kinetics as compared to ferulic acid. The PHA-based films containing BDF displayed > 80% of DPPH inhibition. The growth of crystals inside polymer matrix had a nucleation effect which reduced the glass transition temperature of the films.

Role of Maleic Anhydride-Grafted Poly(lactic acid) in Improving Shape Memory Properties of Thermoresponsive Poly(ethylene glycol) and Poly(lactic acid) Blends

Generally, poly(ethylene glycol) (PEG) is added to poly(lactic acid) (PLA) to reduce brittleness and improve mechanical properties. However, shape memory properties of PEG/PLA blends suffered due to the blend’s incompatibility. To enhance shape memory abilities of the blends, 0.45% maleic anhydride-grafted poly(lactic acid) (PLA-g-MA) was used as a compatibilizer. Thermal and mechanical properties, morphologies, microstructures, and shape memory properties of the blends containing different PLA-g-MA contents were investigated. The compatibilized blend with 2 wt% PLA-g-MA exhibited enhanced tensile modulus, strength, and elongation at break, as well as a lower glass transition temperature and degree of crystallinity than the uncompatibilized blend. Results revealed that PLA-g-MA improved interfacial adhesion between phases and promoted chain entanglement. Shape fixity performance of the compatibilized blends were comparable to that of neat PLA. The compatibilized blend containing 2 wt% PLA-g-MA possessed the best shape fixity and recovery performance. Although a high recovery temperature was expected to enhance the recovery of the PEG/PLA blends, the compatibilized blends can be recovered to their original shape at a lower temperature than the PLA. This study illustrated the possibility of optimizing PLA properties to meet requirements necessary for biomedical applications.

Nanocrystallisation and self-assembly of biosourced ferulic acid derivative in polylactic acid elastomeric blends

HYPOTHESIS

The crystallisation of biosourced ferulic acid derivatives - Bis-O-feruloyl-1,4-butanediol (BDF) - in a polylactic acid (PLA) matrix produces thermoplastic elastomeric blends that are transparent and biodegradable. Elastomeric and transparency are controlled by the domain size. PLA-BDF blends up to a threshold BDF concentration providing elastomeric properties show no evidence of BDF crystallisation. Heat treatment weakens the PLA-BDF interaction, give BDF molecules mobility to interact with nearby BDF molecules, leading to BDF nano-crystallisation.

EXPERIMENTS

PLA-BDF blends were synthesised by hot-melt processing by mixing pure PLA with different concentrations of BDF (0-40 wt%) at 180 °C for 13 min. One set of blends was annealed at 50 °C for 24 h and compared with the unannealed set. The BDF crystallisation in the blends is studied by combining SAXS, SEM, XRD and Polarised Optical Microscopy. Monte-Carlo simulations were performed to validate SAXS data analysis.

FINDINGS

Unannealed PLA-BDF blends of up to the threshold of 20 wt% BDF are dominated by the semicrystalline behaviour of PLA, without any trace of BDF crystallisation. Surprisingly, the PLA-BDF 40 wt% blend shows BDF crystallisation in the form of large and nanoscale structures bonded together by weak interparticle interaction. At concentrations up to 20 wt%, the BDF molecules are homogenously dispersed and bonded with PLA. Increasing BDF to 40 wt% brings the BDF molecules close enough to crystallise at room temperature, as the BDF molecules are still bonded with the PLA network. Annealing of PLA-BDF blends led to BDF nanocrystallisation and self-assembling in the PLA network. Both BDF nanoparticle size and interparticle distance decrease as the BDF concentration increases. However, the number density of BDF nanocrystals increases. The formed BDF nanocrystals have size ranging between 100 and 380 Å with interparticle distance of 120-180 Å. The structure factor and potential mean force confirm the strong interparticle interaction at the higher BDF concentration. Heat treatment weakens the PLA -BDF interaction, which provides mobility to the BDF molecules to change conformation and interact with the nearby BDF molecules, leading to BDF crystallisation. This novel BDF crystallisation and self-assembly mechanism can be used to develop biodegradable shape memory PLA blends for biomedical, shape memory, packaging and energy applications.

Lacerda T. Monomers and Macromolecular Materials from Renewable Resources: State of the Art and Perspectives

A progressively increasing concern about the environmental impacts of the whole polymer industry has boosted the design of less aggressive technologies that allow for the maximum use of carbon atoms, and reduced dependence on the fossil platform. Progresses related to the former approach are mostly based on the concept of the circular economy, which aims at a thorough use of raw materials, from production to disposal. The latter, however, has been considered a priority nowadays, as short-term biological processes can efficiently provide a myriad of chemicals for the polymer industry. Polymers from renewable resources are widely established in research and technology facilities from all over the world, and a broader consolidation of such materials is expected in a near future. Herein, an up-to-date overview of the most recent and relevant contributions dedicated to the production of monomers and polymers from biomass is presented. We provide some basic issues related to the preparation of polymers from renewable resources to discuss ongoing strategies that can be used to achieve original polymers and systems thereof.

Strategic Approach Towards Plastic Waste Valorization: Challenges and Promising Chemical Upcycling Possibilities

Plastic waste, which is one of the major sources of pollution in the landfills and oceans, has raised global concern, primarily due to the huge production rate, high durability, and the lack of utilization of the available waste management techniques. Recycling methods are preferable to reduce the impact of plastic pollution to some extent. However, most of the recycling techniques are associated with different drawbacks, high cost and downgrading of product quality being among the notable ones. The sustainable option here is to upcycle the plastic waste to create high-value materials to compensate for the cost of production. Several upcycling techniques are constantly being investigated and explored, which is currently the only economical option to resolve the plastic waste issue. This Review provides a comprehensive insight on the promising chemical routes available for upcycling of the most widely used plastic and mixed plastic wastes. The challenges inherent to these processes, the recent advances, and the significant role of the science and research community in resolving these issues are further emphasized.