2 research outputs found
Toward a Long-Chain Perfluoroalkyl Replacement: Water and Oil Repellency of Polyethylene Terephthalate (PET) Films Modified with Perfluoropolyether-Based Polyesters
Original
perfluoropolyethers (PFPE)-based oligomeric polyesters (FOPs) of different
macromolecular architecture were synthesized via polycondensation
as low surface energy additives to engineering thermoplastics. The
oligomers do not contain long-chain perfluoroalkyl segments, which
are known to yield environmentally unsafe perfluoroalkyl carboxylic
acids. To improve the compatibility of the materials with polyethylene
terephthalate (PET) we introduced isophthalate segments into the polyesters
and targeted the synthesis of lower molecular weight oligomeric macromolecules.
The surface properties such as morphology, composition, and wettability
of PET/FOP films fabricated from solution were investigated using
atomic force microscopy, X-ray photoelectron spectroscopy, and contact
angle measurements. It was demonstrated that FOPs, when added to PET
film, readily migrate to the film surface and bring significant water
and oil repellency to the thermoplastic boundary. We have established
that the wettability of PET/FOP films depends on three main parameters:
(i) end-groups of fluorinated polyesters, (ii) the concentration of
fluorinated polyesters in the films, and (iii) equilibration via annealing.
The most effective water/oil repellency FOP has two C<sub>4</sub>F<sub>9</sub>–PFPE-tails. The addition of this oligomeric polyester
to PET allows (even at relatively low concentrations) reaching a level
of oil repellency and surface energy comparable to that of polytetrafluorethylene
(PTFE/Teflon). Therefore, the materials can be considered suitable
replacements for additives containing long-chain perfluoroalkyl substances
Plasticization of Polystyrene with Copolymers Based on High Oleic Soybean Acrylic Monomer
In
this work, high oleic soybean oil was used to synthesize
an
acrylic monomer (HOSBM), which was copolymerized with myrcene and
styrene at a 90:10 wt/wt feed ratio to obtain copolymers containing
myrcene (HOSBM-M) and styrene (HOSBM-S). These copolymers were employed
here as macromolecular plasticizers to modify the brittle nature of
polystyrene (PS). Specifically, the soy-based copolymers were added
to commodity polystyrene at 5–20 wt %, and the copolymer effect
on the polymer blends’ structure and behavior was studied.
We report on the blends’ morphology and thermal/mechanical
properties and employ thermodynamic and mechanical models to understand
the interactions between the PS matrix and the HOSBM copolymer dispersed
phase. Microscopy indicated that the mixed materials have a phase-separated
structure composed of the PS-based matrix and the copolymer-based
dispersed phase. Our thermodynamic estimations and measurement of
the thermal transitions showed that the blends are partially miscible,
where a fraction of PS chains migrated into the dispersed phase and
the copolymer was partially situated in the PS matrix. Therefore,
HOSBM-M and HOSBM-S plasticize the PS matrix, decreasing the glass
transition temperature and moduli. The mechanical properties of the
blends depicted a trade-off between the flexural modulus, strength,
and toughness. Although the PS/HOSBM-S blends showed decreased storage/flexural
moduli and strength compared to neat PS, the decline was significantly
lower than that demonstrated by the HOSBM-M blends. Moreover, adding
the HOSBM-S copolymer to PS at 10–15 wt % loading enhances
the material’s extensibility compared to pure PS. The trend
in the toughness values shows that the optimal HOSBM-S loading is
10 wt % to obtain materials with the best middle ground between flexural
modulus, strength, extensibility, and toughness