Biomedical Engineering Reference
In-Depth Information
CN
CN
CN
CN
Pyrrolidine
x
y
O
O
+
+
CH
2
O
O
O
DCM, EtOH, 20
C
O
O
O
O
14
O
14
O
n
n
Fig. 4
Synthesis of poly[(hexadecyl cyanoacrylate)-
co
-methoxypoly(ethylene glycol) cyanoacry-
late] [P(HDCA-
co
-MePEGCA)] copolymer
via
tandem Knoevenagel condensation-Michael addi-
tion reaction
Fig. 5
Scheme of poly
[a-maleic anhydride-w-
methoxypoly(ethylene
glycol)-
co
-ethyl cyanoacry-
late] copolymer
COOH
CN
x
y
O
O
O
O
O
n
(P(HDCA-
co
-MePEGCA)) copolymer by tandem Knoevenagel condensation-Michael
addition reaction between the corresponding cyanoacetate derivatives with formal-
dehyde in the presence of dimethylamine as the catalyst to build the polymeric
backbone (Fig.
4
). In this case, cyanoacrylate monomers are obtained
in situ
during
the reaction and polymerization occurs spontaneously (Peracchia et al.
1997a
).
Interestingly, poly[a-maleic anhydride-w-methoxypoly(ethylene glycol)-
co
-
ethyl cyanoacrylate] copolymers (Fig.
5
) were prepared by radical solution copoly-
merization of poly(ethylene glycol) macromonomer and ECA at 60°C under
azobisisobutyronitrile (AIBN) initiation (Deng et al.
2005
; Xing et al.
2009
). Due
to its amphiphilic properties, this copolymer led to PEGylated nanoparticles upon
self-assembly in aqueous solution.
By using protecting chemistry, a three-arm star cyanoacrylate-telechelic poly-
isobutylene (PIB-CA)
3
was obtained from the polymerization of isobutylene initi-
ated by a tri-functional initiator (Fig.
6
) (Kwon and Kennedy
2007a
). This was
followed by its termination with allyltrimethylsilane and an anti-Markovnikov
addition of HBr. A masked cyanoacrylate moiety was then linked by esterification
prior deprotection to release the cyanoacrylate group. The injection of (PIB-CA)
3
into living tissue yielded a bolus of crosslinked PIB rubber. This approach was also
extended to the copolymerization of (PIB-CA)
3
with ECA initiated by nucleophiles
or living tissues (Kwon and Kennedy
2007b
).
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