TY  - JOUR
A1  - Ghobadi, Ehsan
A1  - Heuchel, Matthias
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Influence of different heating regimes on the shape-recovery behavior of poly(L-lactide) in simulated thermomechanical tests
JF  - Journal of applied biomaterials & functional materials
N2  - Aim: Multifunctional polymer-based biomaterials, which combine degradability with a shape-memory capability and in this way enable the design of actively moving implants such as self-anchoring implants or controlled release systems, have been recently introduced. Of particular interest are approved degradable polymers such as poly(L-lactide) (PLLA), which can be easily functionalized with a shape-memory effect. In the case of semicrystalline PLLA, the glass transition can be utilized as shape-memory switching domain.
 Methods: In this work we applied a fully atomistic molecular dynamics simulation to study the shape-memory behavior of PLLA. A heating-deformation-cooling programming procedure was applied to atomistic PLLA packing models followed by a recovery module under stress-free conditions allowing the shape recovery. The recovery was simulated by heating the samples from T-low = 250 K to T-high = 500 K with different heating rates beta of 125, 40 and 4 K.ns(-1).
 Results: We could demonstrate that the obtained strain recovery rate (R-r) was strongly influenced by the applied simulation time and heating rate, whereby R-r values in the range from 46% to 63% were achieved. On its own the application of a heating rate of 4 K.ns(-1) enabled us to determine a characteristic switching temperature of T-sw = 473 K for the modeled samples.
 Conclusions: We anticipate that the atomistic modeling approach presented should be capable of enabling further study of T-sw with respect to the molecular structure of the investigated SMP and therefore could be applied in the context of design and development of new shape-memory (bio) materials.
KW  - Molecular modeling
KW  - Polymers
KW  - Shape-memory effect
Y1  - 2012
U6  - https://doi.org/10.5301/JABFM.2012.10440
SN  - 2280-8000
VL  - 10
IS  - 3
SP  - 259
EP  - 264
PB  - Wichtig
CY  - Milano
ER  -