Biology Reference
In-Depth Information
7.5
Preparation of Amylose-Polycarbonate
Inclusion Complexes
The aforementioned guest polymers contain the relative polar
linkages in the main-chains and do not have the side groups. Taking
this into consideration, aliphatic polycarbonates as guest polymers
for the vine-twining polymerization were employed, giving rise to
the corresponding inclusion complexes with amylose [31]. The
four hydrophobic polycarbonates with different methylene chain
lengths were used, which were poly(tetramethylene carbonate)
(PC-4), poly(octamethylene carbonate) (PC-8), poly(decamethylene
carbonate) (PC-10), and poly(dodecamethylene carbonate) (PC-
12).
First, PC-4 was investigated as a guest polycarbonate for the
vine-twining polymerization. The preparation of an amylose-PC-4
inclusion complex was carried out under the conditions almost
same as those using polyethers and polyesters as guest polymers
described
earlier
(Fig.
7.2f ).
The
precipitated
product
was
1
characterized by means of the
H NMR, XRD, and IR measurements,
which supported the structures of amylose-PC-4 inclusion complex.
In addition, the structure of the product was investigated by means
of the differential scanning calorimetry (DSC) measurement. In
the DSC thermogram of PC-4, an endothermic peak corresponding
to the melting (
) was observed (Fig. 7.9a), whereas any thermal
transition is not observed in the DSC trace of the product (Fig. 7.9b).
These DSC traces supported that no crystalline PC-4 existed in the
product.
The effect of the methylene chain lengths in the polycarbonates
was investigated on the formation of the inclusion complexes in this
polymerization system using PC-4, PC-8, PC-10, and PC-12 as the
guest molecules. One helical turn of amylose is composed of about
six repeating glucose units and the repeat distance of the helix of
amylose has been reported as ca. 0.80 nm as aforementioned,
whereas the lengths of one unit of PC-4, PC-8, PC-10, and PC-12 were
calculated to be ca. 0.84, 1.38, 1.65, and 1.92 nm, respectively (Fig.
7.10). On the basis of the aforementioned calculations, the ratios of
the proton numbers between H-1 of amylose to
T
m
β
γ
or
of PC-4, PC-8,
β
γ
PC-10, and PC-12 ([
or
]/H-1) in the inclusion complexes were