Well-Defined Amylose Acetate-graft-polylactide Graft Polymers as Compatibilizers for Renewable Polymer Blends

TL;DR

Scientists created a new type of graft polymer from amylose and polylactide to improve compatibility in renewable polymer blends.

Contribution

The first synthesis of polysaccharide-based graft polymers with exclusive C6 grafting and controllable topology.

Findings

AmAc-g-PLA graft polymers effectively compatibilize immiscible StAc and PDLLA blends.

Grafting affects the thermal properties of the polymer segments.

The method allows studying structure–property relationships in biobased polymer blends.

Abstract

Regioselectively substituted amylose acetate-graft-polylactide (AmAc-g-PLA) graft polymers
were synthesized
via grafting-to “click” reaction between C6-azide functionalized
AmAc and alkyne-terminated PLA. Alkyne-terminated PLA synthesized
through organocatalytic ring-opening polymerization (ROP) permitted
control over graft degree of polymerization (DP) and stereochemistry,
while azide functionalized AmAc with tailorable C6-azide degree of
substitution (DS) allowed graft density control. This describes the
first synthesis of polysaccharide-based graft polymers with exclusive
C6 grafting and controllable topology. Thermal analysis indicates
that glass transition temperatures (T
g) of AmAc and PLA segments are affected after grafting-to coupling,
with poly­(l-lactide) (PLLA) grafts maintaining crystallizability.
AmAc-graft-poly­(d,l-lactide) (PDLLA)
graft polymers were effective compatibilizers for immiscible blends
of starch acetate (StAc) and PDLLA as evidenced by small-angle laser
light scattering (SALLS) and phase contrast optical microscopy (PCOM).
This method permits the determination of structure–property
relationships with regard to the effect of graft polymer topology
on blend compatibilization, which will be invaluable in designing
compatibilized biobased polymer blends as sustainable materials.

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