Poly(ethylene trisulfide)/graphene oxide nanocomposites

The final performance of polysulfide nanocomposites is highly affected by the microstructure of these materials. Moreover, interactions between the components involved in the structure of nanocomposites dictate the microstructure. Here, we investigate the nature and mechanism of interfacial interactions between graphene oxide (GO) nanosheets and poly(ethylene trisulfide) macromolecules (PETRS), with and without sodium dodecylbenzenesulfonate (SDBS) as a surfactant. Fourier transform infrared spectroscopy results show that GO nanosheets interact with SDBS molecules through non-covalent C-H center dot center dot center dot O hydrogen bonding between -OH groups of GO nanosheets and -CH3 groups of the SDBS. In addition, interfacial interactions between SDBS-modified GO nanosheets and PETRS macromolecules take place through two main mechanisms: (1) interactions between sulfur-containing segments of PETRS and C=O groups of GO nanosheets and (2) interactions between ethylene segments of polysulfide and C=O groups of GO. X-ray diffraction and transmission electron microscopy results confirm that the presence of SDBS on the interfacial region of GO nanosheets increases the exfoliation extent of GO nanosheets in the PETRS matrix. Also, differential scanning calorimetry and thermogravimetric analyses show that interactions between SDBS-modified GO and PETRS result in extended melting process and degradation range of nanocomposites. Moreover, the melting enthalpy of PETRS macromolecules increases noticeably in the presence of SDBS-modified GO nanosheets. This is in close accordance with the structural behavior of nanocomposites, where the semicrystalline behavior of PETRS macromolecules becomes more dominant in the presence of SDBS-modified GO nanosheets.