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Graphene oxide (GO) is modified with poly(2-ethyl-2-oxazoline) (PEOZ) and poly [(2-ethyl-2-oxazoline-co-(ethylenimine)] (PEOZ-PEI) to enhance its dispersibility in water and epoxy resin. PEOZ with a terminal primary amine and POZ-PEI with multiple backbone secondary amines are synthesized with scalable methods and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and gel permeation chromatography (GPC). GO modifications are performed at room temperature and 90 C with/without N,N 0 -dicyclohexylcarbodiimide (DCC) and modified-GOs are analyzed by FTIR, thermogravimetric analysis (TGA), and scanning electron microscopyenergy-dispersive X-ray spectroscopy (SEM-EDX). It is observed that the polymer incorporation varies based on the reaction condition, polymer type, and functional group type and position. The dispersion quality and stability of modified GOs are studied in water by particle size analyzer and visually and in epoxy resin by rheometer. PEOZ-modified GOs show better dispersibility and stability than PEOZ-PEI-modified GOs in both media since PEOZ is monofunctional, preventing the agglomerate formation and improving polymer exposure to the dispersion media by its longer length and higher water-solubility, whereas PEOZ-PEI has lower water solubility, multiple amines for interactions leading to agglomeration and limited polymer exposure to the dispersion media. The tailorable polymer grafting and the increased dispersibility of modified GOs in both media are promising indicators of their possible applications in composites.

Poly(2-oxazoline)s (POZs) are widely investigated for their applications in various fields due to their unique properties. To exploit and combine different characteristics of the POZ family, 2-oxazoline monomers can be copolymerized to prepare tailor-made copolymers with the desired glass transition temperature (T g), melting temperature (T m), amphiphilicity, and functionality. Here, we report the synthesis and characterization of 2-oxazoline monomers and a range of POZ copolymers produced, thereof. 2-Propyl-2-oxazoline (PrOZ) and 2-pentyl-2-oxazoline (PeOZ) monomers were synthesized by two different methods starting from nitriles or carboxylic acids. A number of POZ copolymers were synthesized by copolymerization of 2-ethyl-2-oxazoline (EOZ) with either one of PrOZ, PeOZ, or 2-phenyl-2-oxazoline (PhOZ) at three different compositions (25:75, 50:50, and 75:25) and three molecular weights (1000, 2000, and 5000 Da). The successful synthesis of the monomers and copolymers was demonstrated through their structural analysis by 1H NMR and FTIR. SEC results confirmed the targeted molar masses of the copolymers and living nature of the polymerization by showing low dispersity values. Thermal properties of the copolymers were studied using DSC and TGA. DSC studies revealed the amorph and random state of the copolymers with obtained T g values for the copolymers in the range of −3 to 84 °C depending on their molecular weight and type of the side chain. While the presence of longer aliphatic side chains resulted in lower T g values, the presence of 2-phenyl substituents on the polymer led to higher T g values. The decomposition temperatures determined by TGA were in the range of 328 to 383 °C depending on the molecular weight, composition, and side chain of the copolymers. It was observed that higher molecular weights led to higher T g values and decomposition temperatures. While copolymers with aliphatic side chains exhibited a single-step decomposition profile, the decomposition of copolymers having aromatic side chains occurred in multiple steps. The variations in the molecular weight, composition, and side chains of the copolymers resulted in a library of tailorable amphiphilic copolymers suitable for multiple applications ranging from biomedical applications to composite manufacturing.

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