Tailoring diamondised nanocarbon-loaded poly(lactic acid) composites for highly electroactive surfaces - extrusion and characterisation of filaments for improved 3D-printed surfaces
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-08-28 |
| Journal | Microchimica Acta |
| Authors | Mateusz CieĆlik, Agnieszka Susik, Mariusz Banasiak, Robert Bogdanowicz, Krzysztof Formela |
| Institutions | University of GdaĆsk, GdaĆsk University of Technology |
| Citations | 18 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research details the development and characterization of a novel poly(lactic acid) (PLA) composite filament, incorporating Carbon Black (CB) and Diamondised Nanocarbons (DNCs), specifically tailored for high-performance electroanalytical applications via Material Extrusion (ME) 3D printing.
- Value Proposition: A new 3D-printable filament formulation (PLA/CB/DNC) achieves high electrical conductivity (0.01 to 0.2 S/cm) while significantly enhancing electrocatalytic performance compared to standard CB-PLA composites.
- Optimal Formulation: The baseline composite (CB20, 20 wt% CB) was modified with low concentrations (5 wt%) of DNCs (Detonation Nanodiamonds or Boron-doped Carbon Nanowalls).
- Enhanced Sensitivity: The CB20_BCNW5 composite achieved a Limit of Detection (LOD) for dopamine of 0.12 ”M, representing a four-fold improvement over the CB-only reference electrode (0.48 ”M).
- Improved Kinetics: DNC addition drastically improved redox kinetics, evidenced by a reduction in the Fe(CN)63-/4- redox peak separation (ÎE) from 250 mV (CB20) down to 172-191 mV (DNC composites).
- Processing Trade-offs: While DNCs accelerate the thermal degradation of PLA during extrusion, they ensure uniform filler distribution, which is critical for forming homogeneous, electrochemically active surfaces.
- Mechanism: CB provides the necessary percolation paths for bulk conductivity, while the DNCs (especially BCNWs) enhance the electrode/electrolyte interface, lowering activation overpotentials and increasing the heterogeneous rate constant (ko).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Polymer Matrix | PLA Ingeo Biopolymer 3D450 | - | Extrusion base material |
| Primary Filler | Carbon Black (CB) Ensaco 250G | - | Used at 20 wt% (CB20) for conductivity |
| DNC Filler Concentration | 5 | wt% | Added to CB20 (total filler load 25 wt%) |
| Electrical Conductivity (AC) | 0.01 to 0.2 | S/cm | Measured via Broadband Dielectric Spectroscopy (BDS) |
| Dopamine LOD (CB20_BCNW5) | 0.12 | ”M | Lowest detection limit achieved |
| Dopamine LOD (CB20_DND5) | 0.18 | ”M | High sensitivity |
| Reference LOD (CB20) | 0.48 | ”M | CB-only composite reference |
| Redox Peak Separation (ÎE) (CB20) | 250 | mV | Fe(CN)63-/4-, 100 mV/s scan rate |
| Redox Peak Separation (ÎE) (CB20_DND5) | 172 | mV | Improved reversibility |
| Extrusion Die Temperature | 200 | °C | Maximum temperature during melt-compounding |
| 3D Printing Temperature | 230 | °C | Used for Material Extrusion (ME) printing |
| PLA Melt Mass-Flow Rate (MFR) | 15.1 ± 0.4 | g/10 min | Untreated PLA granulate (210 °C, 2.16 kg) |
| DND Crystallite Size | 4.4 | nm | Calculated using Scherrer formula |
| BCNW CVD Temperature | 850 | °C | Substrate heating during deposition |
| BCNW Boron Doping Ratio | 2000 | ppm [B]/[C] | Used during MPACVD synthesis |
Key Methodologies
Section titled âKey Methodologiesâ- Composite Extrusion: PLA and fillers (CB ± DNCs) were melt-compounded using a laboratory conical twin screw extruder. Mixing occurred in bypass mode for 8 minutes at 100 rpm screw rotation.
- Thermal Profile: The extruder barrel was heated across three zones (hopper to die) at 140 °C, 170 °C, and 200 °C.
- Filament Formulation: The extruded material was cooled by air and formed into 3D filaments with a diameter of 1.75 mm.
- BCNW Synthesis: Boron-doped Carbon Nanowalls (BCNWs) were grown on micron-sized glassy carbon powder via Microwave Plasma Assisted Chemical Vapour Deposition (MPACVD) at 850 °C and 50 Torr pressure.
- Electrode Fabrication: Conductive disc electrodes (0.4 cm2) were printed using a 3D Pen PRO (ME technology) at 230 °C. The non-conductive body was prepared via vat photopolymerisation (UV-curing resin).
- Physico-chemical Characterization: Materials were analyzed using X-ray Diffraction (XRD), High-Resolution X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM).
- Electrical Testing: AC conductivity was measured using Broadband Dielectric Spectroscopy (BDS) in a temperature range of 0 °C to 40 °C.
- Electrochemical Evaluation: Electrodes were activated in 1M NaOH. Kinetics were assessed using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) with 1 mM [Fe(CN)6]3-/4- in 0.1 M KCl.
- Dopamine Detection: Analytical performance was determined using Differential Pulse Voltammetry (DPV) in 0.05 M PBS (pH = 4.5).
Commercial Applications
Section titled âCommercial Applicationsâ- Disposable Electrochemical Sensors: Rapid, low-cost manufacturing of single-use sensors for environmental monitoring (e.g., trace metals, pollutants) or food safety analysis.
- Point-of-Care (POC) Medical Devices: Development of highly sensitive biosensors for detecting biomarkers or neurotransmitters (like dopamine) in clinical settings, leveraging the high surface area and enhanced kinetics of the DNCs.
- Integrated Microfluidics: Printing conductive electrodes directly into complex 3D-printed microfluidic chips for advanced lab-on-a-chip systems and flow injection analysis (FIA).
- Custom Electronics and Prototyping: Fabrication of geometrically complex conductive components, such as custom traces, interconnects, or specialized heating elements, where standard conductive filaments lack sufficient electrocatalytic activity.
- Advanced Energy Storage: Potential application in high-performance electrochemical devices, including supercapacitors, where the combination of high conductivity (CB) and stable, high-surface-area carbon (DNCs) is beneficial.