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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