Hyperbranched Poly(amidoamine)‐Grafted Graphene Oxide as a Multifunctional Curing Agent for Epoxy‐Terminated Polyurethane Composites

Abstract

Graphene oxide (GO) modified with hyperbranched poly(amidoamine) (PAMAM) structure (GOD) was used as a multifunctional curing agent in the preparation of thermally stable composites from epoxy‐terminated polyurethanes. The multifunctional GOD sample was prepared through a divergent approach by using (3‐Aminopropyl)triethoxysilane (APTES)‐functionalized GO as the core for grafting PAMAM dendrimer by sequential addition of methyl acrylate and ethylenediamine (EDA). Epoxy‐terminated polyurethanes with two different chain extenders of 1,4‐butanediol (BD) and pyromellitic dianhydride (PMDA) were prepared from the reaction of poly(ethylene glycol), hexamethylene diisocyanate, and chain extenders, and subsequent end group transformation of the isocyanate to epoxy functionalities. Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA) proved successful preparation of GOD. TGA indicated improvement in char content and thermal stabilities of the composites with increasing GOD content and using the PMDA chain extender in comparison with the BD. Weight percentages of APTES, methyl acrylate, and EDA in the modified graphene samples were 15.8, 2.2, and 2.2 wt %, respectively, in each of the successive modification process of GO. Structural study of the graphitic and hybrid samples was accomplished with X‐ray diffraction and electron microscopies. A broad peak at about 21° in the patterns of hybrid composites originates from the amorphous structure of polyurethane.

Anti-Counterfeiting Inks Based on Förster Resonance Energy Transfer in Microcrystalline Cellulose-Grafted Poly(amidoamine) for Artificial Industries

“…Modification of MCC with the first generation of PAMAM dendrimers was accomplished using the literature. − Amino groups were added onto the surface of MCC-GM using EDA through a Michel addition reaction. MCC-GM (0.95 g) was dispersed in methanol (60 mL) in a two-necked, round-bottomed flask by sonication for 20 min.…”

A review on microphase separation measurement techniques for polyurethanes

“…110 Spin-diffusion solid-state NMR can be used to measure the degree of phase separation (λ), domain sizes (d) and soft/hard interphase thickness (d in ). Degree of phase separation (λ) can be measured from 1 H dipolar filter spin diffusion NMR experiments using equation (5). The dipolar filter cancels the rigid phase magnetization and retains the mobile phase magnetization…”

“…1,2 The microphase separation originates from the thermodynamic immiscibility between the hard and soft PU segments. [3][4][5] How much phase separation as well as the morphology and size of the separated domains strongly affects the mechanical, thermal, electrical, and functional properties. Controlling the phase separation can strongly influence PU properties.…”

Preparation, Structure and Properties of Urethane-Containing Elastomers Based on Epoxy Terminal Oligomers

“…The deformation and strength properties of the elastomers, based on these oligomers, are only slightly dependent on the presence of moisture. Amines, dicarboxylic acid anhydrides, carboxyl-containing compounds, and imidazoles are used for curing of epoxyurethane oligomers [ 11 , 12 , 13 , 14 , 15 , 16 ].…”