1 research outputs found
Mediated Competitive Hydrogen Bonding Form Mesoporous Phenolic Resins Templated by Poly(ethylene oxide‑<i>b</i>‑ε-caprolactone‑<i>b</i>‑l‑lactide) Triblock Copolymers
A series of immiscible triple crystalline
triblock copolymers, polyÂ(ethylene oxide-<i>b</i>-ε-caprolactone-<i>b</i>-l-lactide) (PEO-<i>b</i>-PCL-<i>b</i>-PLLA), synthesized through sequential ring-opening polymerization,
have been blended with phenolic resin. FTIR spectra revealed that
the ether groups of the PEO blocks were stronger hydrogen bond acceptors
for the OH groups of phenolic resin than were the Cî—»O groups
of the PCL and PLLA blocks. Curing of phenolic with the templates
and hexamethylenetetramine resulted in excluded and confined PCL or
PLLA phases, depending on the phenolic content. This effect led to
the formation of various composition-dependent nanostructures, including
disordered structures, bicontinuous gyroids, hexagonally packed cylinders,
and spherical micelle structures. Small-angle X-ray scattering and
transmission electron microscopy revealed that self-organized mesoporous
phenolic resin formed at phenolic contents of only 30–50 wt
% as a result of an intriguing balance among the contents of phenolic
and the PEO, PCL, and PLLA blocks. An interesting closed-loop mesoporous
structure existed in the phase diagram of the mesoporous phenolic
resins templated by the PEO-<i>b</i>-PCL-<i>b</i>-PLLA triblock copolymers