  Amorphous materials exhibit peculiar mechanical and vibrational properties,
including non-affine elastic responses and excess vibrational states, i.e., the
so-called boson peak. For polymer glasses, these properties are considered to
be affected by the bending rigidity of the constituent polymer chains. In our
recent work [Tomoshige, et al., Sci. Rep. 9 19514 (2019)], we have revealed
simple relationships between the variations of vibrational properties and the
global elastic properties: the response of the boson peak scales only with that
of the global shear modulus. This observation suggests that the spatial
heterogeneity of the local shear modulus distribution is insensitive to changes
in the bending rigidity. Here, we demonstrate the insensitivity of elastic
heterogeneity by directly measuring the local shear modulus distribution. We
also study transverse sound wave propagation, which is also shown to scale only
with the global shear modulus. Through these analyses, we conclude that the
bending rigidity does not alter the spatial heterogeneity of the local shear
modulus distribution, which yields vibrational and acoustic properties that are
controlled solely by the global shear modulus of a polymer glass.
