Chemistry Reference
In-Depth Information
and nifedipine, with HPSO being more effective than HPESO. The results
suggested that these novel soybean-oil-based amphiphilic polymers have
great potential for drug delivery and pharmaceutical formulations. Zhang
et al.
87
applied ESO as an additive to wheat gluten (WG) to modify the
properties of renewable and bio-degradable natural polymer materials. The
combination of the plasticization and cross-linking effects derived from
ESO resulted in good retention of mechanical strength for the plasticized
WG-ESO materials as compared to those without 10 wt% mobile ESO
additives. Palacios-Jaimes et al.
88
modified polypropylene (PP) membranes
with AESO for the treatment of waste water. AESO was grafted onto the
surface of microporous PP membranes by using a UV radiation method,
which increased the hydrophilicity of the membrane surface and the
modified membrane possessed filtration capabilities and removed 52% of
the color and reduced 95% of the turbidity from industrial residual water.
It is interesting that modifying PP membranes using vegetable oils as
monomers can produce sustainable membranes, with filtration capabil-
ities. These membranes, after reuse, could have the possibility of bio-
degradation. The method is easy, low cost and environmentally friendly.
5.3 Castor Oil: Polymer Synthesis and Applications
5.3.1 Use of Castor Oil Directly for Polymer Synthesis
In contrast to soybean oil, castor oil is a non-food oil, with double bonds and
hydroxyl groups evenly distributed throughout its triglyceride fatty acid
chains. The average number of hydroxyl groups per triglyceride is about 2.7
and about 90% of the fatty acids in castor oil are ricinoleic acid (Figure 5.4).
5
With this inherently available functionality, castor oil can be used as a
polyol for the direct synthesis of cross-linked PU resins with various
isocyanate compounds such as hexamethylene diisocyanate (HDI), tolyene-
2,4-diisocyanate (TDI), and isophorone diisocyanate (IPDI) and so on.
Unfortunately, the resulting PUs are soft due to the low cross-linking density
resulting from the low hydroxyl number of castor oil. To overcome this
problem, Teramoto et al.
89
used glycerol, an abundant bio-based triol with a
O
OH
O
O
OH
O
O
OH
O
Castor oil
Figure 5.4
Structure of a castor oil triglyceride.
