利用石墨烯填料和幾丁聚醣增強天然橡膠複合材料之 機械、熱學與電學性能

Abstract

本研究透過乳膠水性微分散製程，開發以天然橡膠/幾丁聚醣（NR-CHI）複合材料為基礎的生物聚合物薄膜。為提升複合材料的性能，添加了石墨烯填料，包括表面改質石墨烯奈米與商業級石墨烯。幾丁聚醣作為有效的分散劑，能促進石墨烯填料在聚合物基材中的均勻分散，並經由場發射掃描電子顯微鏡（FE-SEM）影像驗證。傅立葉轉換紅外光譜（FTIR）與X射線繞射（XRD）分析顯示，NR-CHI與石墨烯填料之間存在強烈的氫鍵與范德華力，這有助於填料的分散性與介面鍵結的增強。 石墨烯填料的加入顯著提升了複合材料的機械性能、熱穩定性與導電性。與純天然橡膠薄膜相比，楊氏模數增加近100倍，電導率達到10⁻⁴ S/cm。此外，對非極性溶劑的耐化性亦有所提升，使該複合材料在嚴苛環境中具有更廣泛的應用潛力。抗菌測試結果顯示，該複合材料對革蘭氏陽性菌、革蘭氏陰性菌以及真菌具有抑菌效果。幾丁聚醣的加入可完全抑制金黃色葡萄球菌與部分抑制大腸桿菌50%，但對於真菌的抗菌活性略有下降。當加入30 phr的GNP時，對S. aureus與A. niger的抑菌率分別達到99.98%與94.31%，但由於GNP中的氮含量影響抗菌效率，對E. coli的抑制效果仍有限。NR-CHI-GC90複合材料展現平衡的抗菌性能，對S. aureus、E. coli與A. niger的抑菌率分別達97.29%、55.04%與93.85%。 壓阻測試強調NR-CHI-GC90複合材料搭配銀電極作為可穿戴感測器在人體動作偵測上的適用性。該感測器在1至6 Hz頻率範圍內表現穩定的電性響應，於7000次壓力循環下具備良好的重複性，並在10%應變下經過800次伸縮循環後展現優異的耐久性。儘管在彎折測試中因微裂縫形成而導致電阻逐漸變化，感測器仍能保持穩定響應，顯示其機械強度與長期穩定性。即時應用測試，包括手指動作、手腕齒輪運動與足部敲擊偵測，展示了該複合材料在可穿戴健康監測與人機互動方面的潛力。 研究結果顯示，NR-CHI-GC90複合材料在高效能感測器、生醫裝置與抗菌塗層等生物可分解電子應用領域具備高度潛力，並為開發下一世代柔性電子材料提供了永續的解決方案。

This study developed biopolymer films based on natural rubber/chitosan (NR-CHI) composites through a latex aqueous micro-dispersion process. Graphene fillers, including surface-modified graphene nanoplatelets (GNP) and graphene commercial-grade (GC), were incorporated to enhance the properties of the composites. Chitosan (CHI) served as an effective dispersing agent, facilitating the uniform suspension of graphene fillers within the polymer matrix, as confirmed by FE-SEM imaging. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) analyses revealed hydrogen bonding and van der Waals interactions between NR-CHI and the graphene fillers, contributing to enhanced filler dispersion and improved interfacial bonding. The incorporation of graphene fillers significantly enhanced the mechanical properties, thermal stability, and electrical conductivity of the composites. The Young’s modulus increased by nearly 100-fold compared to neat NR films, while electrical conductivity reached 10⁻⁴ S/cm. Furthermore, chemical resistance against non-polar solvents improved, expanding the potential applications of the composites in harsh environments. Antimicrobial tests demonstrated the efficacy of the composites against gram-positive bacteria (Staphylococcus aureus), gram-negative bacteria (Escherichia coli), and fungi (Aspergillus niger). The NR-CHI-GC90 composite demonstrated balanced antimicrobial properties, achieving 97.29%, 55.04%, and 93.85% reductions for S. aureus, E. coli, and A. niger, respectively. Piezoresistive tests emphasized the suitability of NR-CHI-GC90 composites with silver printed electrode as wearable sensors for human motion detection. The sensors exhibited stable electrical responses across 1 – 6 Hz frequencies, excellent repeatability under 7000 pressure cycles, and superior durability over 800 stretch/release cycles at 10% strain. Despite gradual resistance changes due to micro-crack formation during bending tests, the sensors maintained consistent responses, underscoring their mechanical robustness and long-term stability. Real-time applications, including the detection of finger movements, wrist cogwheel motion, and foot tapping, demonstrated the potential of the composites for wearable health monitoring and human-machine interaction. These findings position NR-CHI-GC90 composites as promising candidates for biodegradable electronic applications, including high-performance sensors, biomedical devices, and antimicrobial coatings, while offering a sustainable approach to developing next-generation flexible electronic materials.