The alkylated graphene oxide (AGO) was synthesized by S_N2 reaction between graphene oxide and octylamine, and its dispersion stability in tetrahydrofuran (THF) and thermodynamic compatibility with poly(vinylidene chloride) (PVDC) were analyzed. AGO was compounded with PVDC, which is the most representative polymer with gas barrier properties, as a solution to improve the water barrier properties of the PVDC matrix film. The degree of alkylation of the mixture (~31 wt%) was characterized and calculated through Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The dispersion stability of AGO in THF, which is a good solvent for PVDC, was quantified by light scattering, operating in transmittance mode for 3 days. Alkylation lowered the delta transmittance of the dispersion from 72% to 0.17%. The hydrophobic character of AGO, in comparison with that of GO and PVDC films, was confirmed through contact angle measurements. The inclusion of AGO in the PVDC matrix film improved its water transmission rate from 1.7 to 0.2 g/(m² day). Based on the experimental data, the water barrier mechanism in AGO/PVDC nanocomposite films is herein suggested.

본 연구에서는 대표적인 기체 차단 고분자인 폴리비닐리덴클로라이드(poly(vinylidene chloride), PVDC) 내 수분 차단성 향상을 목표로 그래핀 옥사이드를 옥틸아민을 이용하여 알킬화를 진행하여 용매 내 분산 안정성, PVDC와의 상용성 및 소수성이 확보된 알킬화 그래핀 옥사이드(alkylated graphene oxide, AGO)를 합성하였고 이를 FTIR, XPS, TGA를 통해서 확인하였다. 또한 PVDC의 용매 테트라하이드로퓨란(tetrahydrofuran, THF) 내 AGO의 분산 안정성을 Turbiscan을 통해서 확인하였다. AGO의 소수성 및 표면에너지를 접촉각을 통해서 확인한 후 PVDC/AGO 나노복합필름을 제조하였고, 그것의 수분 차단 특성 및 투과도를 측정 및 분석하고 전체적인 AGO의 수분 차단 메커니즘을 모식도로 제시하였다.

Keywords: poly(vinylidene chloride), graphene oxide, alkylation, dispersion stability, water barrier