Chemistry Reference
In-Depth Information
moduli ranging from 33.6 to 554.0 MPa, and elongation-at-break values
ranging from 235 to 291%. This work provides a new way of utilizing re-
newable resources to prepare environmentally friendly bio-based polymers
with high performance for coating and adhesive applications. Among all
these adhesives, pressure-sensitive adhesives (PSAs) are one of the most
widespread groups of adhesives. Ahn et al.
82
produced thermally stable
transparent PSAs from epoxidized and dihydroxyl soybean oil (DSO) with
peel strengths comparable to current PSAs. The main challenge in com-
mercializing these oleo-based PSAs is reducing the curing time. They de-
signed and synthesized a fast-curing co-polymer from ESO and DSO for PSA
applications without using petrochemicals. Most current flexible petroleum-
based plastics and PSAs have fairly low thermal stabilities, while low T
g
, high
T
m
and low coecient of thermal expansion (CTE) are favorable for PSAs.
The PSAs synthesized from ESO and DSO have low T
g
values of
34.29 1C,
high T
m
values of above 250 1C, and low CTE values of 11.5 ppm K
1
, with
transparency similar to glass.
5.2.3.5 Other Applications
Soybean oil and its derivatives have many other applications. For example,
ESO not only increases the toughness of PLA, but also improves the hydro-
lytic stability of poly(
D
-lactide) (PDLA). Fu et al.
83
synthesized a multi-arm
star polymer ESO-PLA by ROP of
DL
-lactide using multifunctional ESO as an
initiator. The results revealed that linear poly(
DL
-lactide) (PDLLA) films
underwent water erosion more readily than the star-shaped ESO-PLA, and
the decrease in molecular weight and weight loss ratio of the star-shaped
ESO-PLA was lower than that of linear PDLLA. There are two reasons for this,
one is that a strong intermolecular force may be present in the star-shaped
polymer because of its long-arm chain undergoing twining behavior, pre-
venting water erosion of the polymer. The other is that ESO can minimize
the amount of trapped water which slows down the permeation of water into
the polymer, resulting from the hydrophobic nature of ESO. Ren et al.
84
used
isocyanate and AESO as a coupling agent to modify kenaf fibers and Lin
et al.
85
expanded applications to bio-medical fields. They utilized soybean oil
as a co-delivery system for DNA and subunit vaccines. Liposome-polymer
transfection complexes (LPTCs) were formed by two hydrophilic polymers,
polyethyleneimine (PEI) and PEG, with soybean oil. The soybean oil was used
to form the liposome structure via sonication. Soybean oil may allow for the
addition of immunostimulatory components such as the saponin adjuvant
Quil A. Immunostimulatory agents are typically hydrophobic in nature
and have immunogenicity, thus the addition of soybean oil through polar
interactions improved the adjuvant effect of the vaccine. Additionally,
Abdekhodaie et al.
86
used hydrolyzed polymers of soybean oil (HPSO) and of
epoxidized soybean oil (HPESO) as drug-delivery systems and pharma-
ceutical excipients. HPSO and HPESO polymers were surface active and able
to increase the wetting of solid tablets of the hydrophobic drugs ibuprofen
