1 research outputs found
Free Radical Polymerization Behavior of the Vinyl Monomers from Plant Oil Triglycerides
A one-step
method of plant oil direct transesterification was used
to synthesize new vinyl monomers from sunflower (SFM), linseed (LSM),
soybean (SBM), and olive (OVM) oils. The degree of unsaturation in
plant oil fatty acids was used as a criterion to compare the free
radical polymerization behavior of new monomers. The number-average
molecular weight of plant oil-based homopolymers synthesized in toluene
in the presence of AIBN at 75 °C varies at 11 000–25 000
and decreases as follows: polyÂ(OVM) > polyÂ(SFM) > polyÂ(SBM)
> polyÂ(LSM),
corresponding to increasing degree of unsaturation in the monomers.
Rate of polymerization depends noticeably on the degree of unsaturation
in monomers. Due to the allylic termination, chain propagation coexists
with effective chain transfer during polymerization. The obtained
values of <i>C</i><sub>M</sub> (ratio of chain transfer
and propagation rate constants) depends on monomer structure as follows: <i>C</i><sub>M</sub>(LSM) > <i>C</i><sub>M</sub>(SBM)
> <i>C</i><sub>M</sub>(SFM) > <i>C</i><sub>M</sub>(OVM). <sup>1</sup>H NMR spectroscopy shows that the fraction
of
the reacting allylic atoms does not vary significantly for the synthesized
monomers (7–12%) and is determined entirely by plant oil degree
of unsaturation. The glass transition temperature of homopolymers
[<i>T</i><sub>g</sub> = 4.2 °C for polyÂ(SFM), <i>T</i><sub>g</sub> = −6 °C for polyÂ(SBM)] from new
monomers indicates that varying biobased fragments in copolymers might
considerably change the intermolecular interactions of macromolecules
and their physicochemical properties