Transitional
metal carbides and nitrides (MXenes) have promise
for incorporation into multifunctional composites due to their high
electrical conductivity and excellent mechanical and tribological
properties. It is unclear, however, to what extent MXenes are also
able to improve the mechanical properties of the composites and, if
so, what would be the optimal flake size and morphology. Herein, Ti
3
C
2
T
x
MXene is demonstrated
to be indeed a good candidate for mechanical reinforcement in polymer
matrices. In the present work, the strain-induced Raman band shifts
of mono-/few-/multilayer MXenes flakes have been used to study the
mechanical properties of MXene and the interlayer/interfacial stress
transfer on a polymer substrate. The mechanical performance of MXene
was found to be less dependent upon flake thickness compared to that
of graphene. This enables Ti
3
C
2
T
x
MXene to offer an efficient mechanical reinforcement
to a polymer matrix with a flake length of >10 μm and a thickness
of 10s of nanometers. Therefore, the degree of exfoliation of MXenes
is not as demanding as other two-dimensional (2D) materials for the
purpose of mechanical enhancement in polymers. In addition, the active
surface chemistry of MXene facilitates possible functionalization
to enable a stronger interface with polymers for applications, such
as strain engineering and mechanical enhancement, and in materials
including membranes, coatings, and textiles.