Biomedical Engineering Reference
In-Depth Information
Scheme 25
Propagation modes for the homopolycyclotrimerization of silyldiynes
The computer simulation model is thus consistent with the structure of the
real polymer. Estimation of the three different growth modes gave possibil-
ities of 64%, 34%and2%fortheP
1
M
2
,P
2
M
1
and P
3
modes, respectively.
Although more than 1
3(or36%) of the propagation modes are via the in-
tracyclotrimerization reactions, most of the cycles are small, being formed by
only two monomer units mainly due to the close proximity of the 1 and 2 pos-
itions of the newly formed 1,2,4-trisubstituted benzenes. The small rings are
strung together like beads in a necklace. This structure model is in agreement
with the excellent solubility of the polymer, although it contains numerous
cyclic structures.
As mentioned above, the homopolycyclotrimerization was limited to
a small number of diynes in terms of generation of soluble polymers. To over-
come the problem of uncontrolled cross-linking reactions and to improve the
solubility of the polymers, copolycyclotrimerizations of aromatic diynes with
monoynes (V-XI) were carried out (cf., Scheme 24). This approach worked
very well: all the copolycyclotrimerization reactions proceeded smoothly with
good controllability, producing completely soluble hyperbranched copoly-
/
