High-damping polyurethane-based composites modified with amino-functionalized graphene

Abstract

A series of damping composites containing polyurethane/poly (butyl methacrylate) (PU/PBMA) as the polymer matrix and graphene nanoplates (GNP) or amino-functionalized graphene nanoplates (NGNP) as a modifier was successfully synthesized through in situ polymerization. The chemical structure, microphase configuration, damping properties, and thermal stability of the GNP–PU/PBMA and NGNP–PU/PBMA composites were evaluated. Fourier-transform infrared and X-ray photoelectron spectroscopic studies revealed that the amino (–NH2) groups on the NGNP surface presumably reacted with the isocyanate (R–N = C = O) groups of the polymer matrix. This led to robust bonding between the NGNP and the hard segments in PU, resulting in an NGNP/polymer-matrix compatibility superior to that of GNP–PU/PBMA. Structural investigations based on scanning electron microscopy and atomic force microscopy revealed dispersion-state-related differences between the GNP and NGNP in the PU/PBMA matrix; the amino-functionalized GNP were more uniformly dispersed in the polymer matrix than their unmodified counterparts, and microphase separation between the hard and soft segments intensified in NGNP–PU/PBMA, resulting in a greater degree of phase separation, as confirmed by small-angle X-ray scattering analysis. Dynamic mechanical analysis (DMA) revealed that the maximum damping peak (tan δmax) of the composite with 0.7 wt.% NGNP was 22.7% higher than that of pristine PU/PBMA. Additionally, a large independent damping peak appeared in the DMA curve of 0.7 wt.% NGNP–PU/PBMA in the high-temperature range, indicating broadening of the damping temperature range. Moreover, the NGNP incorporation effectively improved the thermal stability of the composite. Overall, this study demonstrates the viability of realizing PU-based materials with excellent thermodynamic and damping properties by incorporating amino-bearing NGNP.