In this study, we report the fabrication of high-performance polymer nanocomposites by incorporating directionally aligned non-oxidized graphene flakes (NOGF) into a polydimethylsiloxane (PDMS) matrix. NOGF was synthesized via exfoliation of graphite intercalation compounds (GIC) without oxidative treatment, preserving its graphitic structure and minimizing defect formation. A unidirectional freeze-casting method was employed to construct highly aligned three-dimensional NOGF aerogels, which were then infiltrated with PDMS to produce flexible, lightweight composites. The resulting NOGF/PDMS composites exhibited markedly improved mechanical properties compared to reduced graphene oxide (rGO)-based composites, achieving a tensile strength of 2.0 MPa, a Young’s modulus of 4.5 MPa, and a toughness of 2.4 MJ/m³, while rGO/PDMS composites reached 1.7 MPa, 2.3 MPa, and 1.2 MJ/m³, respectively. These improvements are attributed to the structural integrity and low defect density of NOGF. This work demonstrates that employing defect-suppressed, aligned graphene architectures offers an effective strategy for reinforcing polymer matrices, even at low filler content, providing a promising platform for developing mechanically robust nanocomposites.

본 연구에서는 방향성 있게 정렬된 비산화 그래핀 플레이크(non-oxidized graphene flakes, NOGFs)를 PDMS와 복합화하여 고성능 고분자 나노 복합재를 제작하였다. 흑연 삽입화합물(GIC)을 산화 처리 없이 박리하여 합성한 NOGF는 구조적 완전성과 낮은 결함 밀도를 유지하였으며, 단일 방향 동결주조법을 통해 3차원 에어로겔을 형성하였다. 결과적으로 얻어진 NOGF/PDMS 복합체는 환원 그래핀 산화물(rGO)을 기반으로 한 복합재에 비해 현저히 향상된 기계적 물성을 나타내었다. 인장 강도는 2.0 MPa, 영률은 4.5 MPa, 인성은 2.4 MJ/m³로, rGO/PDMS 복합체의 1.7 MPa, 2.3 MPa, 1.2 MJ/m³에 비해 우수한 물성을 보였다. 이러한 향상은 NOGF의 구조적 완전성과 낮은 결함 밀도에 기인한다. 본 연구는 결함이 억제된 정렬 그래핀 구조체를 활용하여, 낮은 충전제 함량에서도 기계적 물성이 우수한 나노복합체 개발 전략을 제시한다.

Keywords: non-oxidized graphene flakes, reduced graphene oxide, unidirectional freeze-casting, anisotropic structure, mechanical properties.

This work was supported by Korea Evaluation Institute of Industrial Technology (KEIT) grant funded by the Korea government (MOTIE) (No. RS-2024-00421052). This work is also supported by the Global Joint Research Program funded by the Pukyong National University (202506020001).

The authors declare that there is no conflict of interest.