ma6b02473_si_001.pdf (176.54 kB)
Structure and Thermal Transitions in a Biomedically Relevant Liquid Crystalline Poly(ester amide)
journal contribution
posted on 2017-02-20, 18:21 authored by F. Bedoui, N. S. Murthy, J. KohnThere is still a need to develop
bioresorbable polymers with high
strength and high modulus for load-bearing biomedical applications.
Here we investigate the liquid crystalline structural features of
poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate), poly(DTD DD),
a new bioresorbable poly(ester amide) that is currently studied in vivo as a slow-degrading implantable biomaterial for
load bearing applications. Thermally induced structural changes in
poly(DTD DD) were studied using simultaneously differential scanning
calorimetry (DSC) and X-ray scattering. The hexatic SmB organization
of the polymer chains that exists at room temperature becomes progressively
disordered upon heating, changing into a SmF phase and then into a
smectic C phase at 60 °C before turning into a free-flowing melt
at 130 °C. X-ray scattering data and thermal analysis indicate
the presence of a 2D ordered structure in the polymer melt. A structural
model with an interesting 3-fold symmetry in the packing of the side
chains around the rigid aromatic main chain, and the packing of these
chains into fibrils is proposed. The liquid crystalline behavior of
poly(DTD DD) makes it possible to melt process it at low temperatures
without thermal degradation. This is a noteworthy advantage for the
use of poly(DTD DD) as a high strength, readily processable, yet biodegradable
polymer.