Appeal No. 2005-0590
Application 09/854,435
the range of “units” or “segments” in a polyorthoester chain of “at least 5” to no specified upper
limit. We note that there is no limitation on the manner in which the claimed polyorthoesters are
prepared, and thus the claimed polyorthoesters include block as well as random distribution of
the “units” or ‘segments” in the polymer chain. See generally, In re Thorpe, 777 F.2d 695, 697,
227 USPQ 964, 966 (Fed. Cir. 1985).2
We find that Sparer would have disclosed to one of ordinary skill in this art
polyorthoester polymers which are prepared by reacting a diketene acetal with certain diols,
wherein the diols are reacted either separately, to form a block copolymer, or in admixture, to
form a random polymer (e.g., col. 1, ll. 33-35, and col. 4, ll. 36-45). One of ordinary skill in this
art routinely following the teachings of Sparer would have arrived at polyorthoesters which
contain units that correspond to “A units” “R2,” “R3” and “R4” of structural formula (I) of
appealed claim 1, wherein the units are hard or rigid units, flexible or soft units, and hard or rigid
units, respectively, and unit “R4” is a hydrogen bonding unit containing at least one amide,
imide, urea and urethane group (e.g., col. 2, l. 42, to col. 3, l. 43, col. 3, l. 65, col. 4, ll. 13-19).
The amounts of and arrangement of the respective units in the polyorthoesters are disclosed to be
based on the properties desired for bioerodibility and in the fabrication of medical devices, such
as implants, and controlled release drug delivery forms, wherein the polymer can be cross-linked
(e.g., col. 1, ll. 7-22 and 34-68, col. 2, ll. 2-28, col. 4, ll. 16-45). Thus, because the hydrogen
bonding unit can be present at least in some amount, the polyorthoesters of Sparer differ from the
claimed polyorthoesters encompassed by claim 1 in the absence of unit(s) corresponding to “A
unit” “R1,” that is, wherein “A” is derived from an α-hydroxyacid containing diol to provide
units of the structure shown in the claim 1 (specification, e.g., page 5, ll. 19-21).
2 We note, in this respect, that appealed claim 17 is drawn to a method of preparing a claimed
polyorthoester wherein a diketene diacetal is reacted with at least two and optionally more diols
without specifying whether the diols are reacted with the diketene acetal separately, resulting in
a block polymer, or in mixtures, resulting in a random polymer. See also specification, e.g., page
13, l. 23, to page 14, l. 2, and page 16, l. 27, to page 17, l. 2. In contrast, appealed claims 18 and
19 are couched in product-by-process format wherein the claimed polyorthoester product is
characterized as being prepared by the reaction of a diketene diacetal and a polyol or mixture of
polyols even though diols are structurally depicted and specified in these claims. See Thorpe,
supra. We interpret claims 18 and 19 to encompass random or block polyorthoesters
encompassed by appealed claim 1.
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