Biomedical Engineering Reference
In-Depth Information
O
O
O
O
O
O
O
...
CO
D
O
H
C
NH
CH
R
C
O D O
C
CH
R
NH
C
(CH
2
)
y
C
NH
CH
R
C
CH
R
NH
l
k
C
H
O
O
k
= 1.0, 0.8, 0.6;
l
= 1 - k
R = CH
2
CH(CH
3
)
2
, CH
2
C
6
H
5
; D = (CH
2
)
4
, (CH
2
)
6
, (CH
2
)
8
; y = 4, 8.
Figure 5.10
Epoxy-PEAs on the basis of
trans
- epoxy - succinic acid.
...
CO
(CH
2
)y
CO
NH
CH
R
CO O
D
O
CO
CH
R
NH
CO (CH
2
)y CO
NH
CH (CH
2
)
4
NH
C
k
l
O
O
(CH
2
)
n
CH
3
n
= 8, 12, 16
k =
0.8, 0.6, 0.4, 0.2;
l =
1 - k
R = CH
2
CH(CH
3
)
2,
CH
2
C
6
H
5
; D = (CH
2
)
6
; y = 4, 8.
Figure 5.11
Brush - like PEAs containing long - chain
n
- alkyl substituents.
urea)s, PEEUs, having polyethylene glycol like polymeric backbones and showing
enhanced water solubility as compared with the said arginine-based PEAs.
Biodegradable cationic PEAs were also obtained [57] by covalent conjugation to
PEA-polyacids with arginine methyl ester and agmatine.
Unsaturated PEAs.
One of the most convenient and universal ways to render
biodegradable polymers functional is the incorporation of unsaturated double
bonds in the polymeric backbones [58] . Unsaturated PEA s ( UPEA s) containing a
variable amount of double bonds in the backbones were obtained by Katsarava,
Chu, and coworkers [19, 27-30, 45] using TAADs on the basis of 1,4-butendiol, or
DAD based on fumaric acid as monomers/comonomers in combination with satu-
rated TAADs and DADs.
The unsaturated double bonds can be subjected to various chemical and photo-
chemical transformations.
Epoxy - PEAs.
Very recently Katsarava, Tugushi, and coworkers [20, 46] have
synthesized a new class of functional biodegradable polymers - epoxy - PEAs - using
active di -
p
- nitrophenyl ester of
trans
-epoxy-succinic acid as a monomer, or comon-
omer in combination with DADs containing
- alkylenedicarboxylic acids in AP
with TAADs. They have the structure given in Figure 5.10.
The epoxy groups of PEAs can be subjected to various chemical transformations
under mild conditions, as well as thermal or chemical curing.
Brush - like PEAs
. PEAs with a brush-like architecture containing long-chain alkyl
substituents were obtained by Katsarava and coworkers [59] using l - lysine
n
- alkyl
esters as comonomer in a mixture with TAADs in AP with DADs. They have the
structure shown in Figure 5.11 .
α
,
ω
