  The Daya Bay reactor antineutrino experiment has recently measured the
neutrino mixing parameter sin22{\theta}13 by observing electron antineutrino
disappearance over kilometer-scale baselines using six antineutrino detectors
at near and far distances from reactor cores at the Daya Bay nuclear power
complex. Liquid scintillator contained in transparent target vessels is used to
detect electron antineutrinos via the inverse beta-decay reaction. The Daya Bay
experiment will operate for about five years yielding a precision measurement
of sin22{\theta}13. We report on long-term studies of poly(methyl methacrylate)
known as acrylic, which is the primary material used in the fabrication of the
target vessels for the experiment's antineutrino detectors. In these studies,
acrylic samples are subjected to gaseous and liquid environmental conditions
similar to those experienced during construction, transport, and operation of
the Daya Bay acrylic target vessels and detectors. Mechanical and optical
stability of the acrylic as well as its interaction with detector liquids is
reported.
