Appeal No. 95-1079
Application 08/037,192
Appellants disclose that the stable free radical agents
employed in the claimed process are well known in the art and
that they have been “used to reversibly cap the ends of growing
chains to produce oligomers ...” (specification, page 13).
According to appellants, the
... stable free radical agents function as moderators
to harness the normally highly reactive and indis-
criminate intermediate growing polymer chain free
radical species as thermally labile covalent adducts
comprised of an oligomer or incipient polymer product
and a stable free agent. The rate at which these
adducts homolytically cleave back into a free radical
terminated polymer chain and a stable free radical is
believed to be a rate limiting step which regulates the
addition of monomer to the growing chain and which
precludes premature chain termination which termination
would ordinarily yield polymer products having broad
polydispersities. Also, under the polymerization
conditions of the present invention, all chains are
initiated at about the same time. Initiating all the
chains at about the same time and limiting the rate of
addition of monomer to the growing chains allows the
bulk polymerization stage to be stopped or suspended,
in a highly reproducible manner, at the aforementioned
desired levels of monomer to polymer conversion.
... If the [molar ratio of stable free radical
agent to free radical initiator] is too high then the
reaction rate is noticeably inhibited. If the [molar
ratio of stable free radical agent to free radical
initiator] is too low then the reaction product has
undesired increased polydispersity. [Specification,
page 14.]
From what appellants have described, we find a reasonable basis
for the examiner to conclude that the functions associated with
appellants’ “stable free radical agent” overlap with the
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