The melt surface tension for a series of hyperbranched polymers was measure
d using the micro-Wilhelmy wetting technique. The surface tension was found
to be extremely high for the hydroxyl-terminated hyperbranched polymers an
d approached that of water extrapolated to high temperature. Substituting a
n alkane on the end groups reduced the surface tension to the point where a
large degree of substitution produced a surface tension equivalent to that
of pure alkane. Water contact angle measurements were used to show the sol
id surface tension (surface energy density) was similarly affected by alkan
e substitution. Liquids that predominantly interact with the surface via di
spersion (nonpolar) forces allowed determination of the surface dispersive
contribution to the surface tension. Extrapolation of the melt data to room
temperature yielded the total surface tension, and the difference between
the total and dispersive surface tensions gave the nondispersive contributi
on. This was found to be a linear function of the number of hydroxyl groups
, for a given generation hyperbranched polymer, demonstrating the hydroxyl
end groups each linearly contribute to the surface tension. We use this as
partial proof that the end groups can significantly influence the surface p
roperties. The water contact angle for a polyethylene film was not found to
be significantly affected by addition of a small amount of alkane-terminat
ed hyperbranched polymer.