Giannelis, Emmanuel P.
KAUST Grant NumberKUS-C1-018-02
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AbstractCommercial polylactide (PLA) was converted and endowed with shape-memory properties by synthesizing ionic hybrids based on blends of PLA with imidazolium-terminated PLA and poly[ε-caprolactone-co-d,l-lactide] (P[CL-co-LA]) and surface-modified silica nanoparticles. The electrostatic interactions assist with the silica nanoparticle dispersion in the polymer matrix. Since nanoparticle dispersion in polymers is a perennial challenge and has prevented nanocomposites from reaching their full potential in terms of performance we expect this new design will be exploited in other polymers systems to synthesize well-dispersed nanocomposites. Rheological measurements of the ionic hybrids are consistent with the formation of a network. The ionic hybrids are also much more deformable compared to the neat PLA. More importantly, they exhibit shape-memory behavior with fixity ratio Rf ≈ 100% and recovery ratio Rr = 79%, for the blend containing 25 wt % im-PLA and 25 wt % im-P[CL-co-LA] and 5 wt % of SiO2–SO3Na. Dielectric spectroscopy and dynamic mechanical analysis show a second, low-frequency relaxation attributed to strongly immobilized polymer chains on silica due to electrostatic interactions. Creep compliance tests further suggest that the ionic interactions prevent permanent slippage in the hybrids which is most likely responsible for the significant shape-memory behavior observed.
CitationOdent J, Raquez J-M, Samuel C, Barrau S, Enotiadis A, et al. (2017) Shape-Memory Behavior of Polylactide/Silica Ionic Hybrids. Macromolecules 50: 2896–2905. Available: http://dx.doi.org/10.1021/acs.macromol.7b00195.
SponsorsJ.O. gratefully thanks Wallonie-Bruxelles International (WBI, mobility grant) and the Belgian American Educational Foundation (BAEF) for its financial support. J-M.R. is a research associate at F.R.S.-FNRS (Belgium). We gratefully acknowledge support from NPRP Grant No. 5-1437-1-243 from the Qatar National Research Fund. We also acknowledge use of facilities at the Cornell Center for Materials Research (CCMR) supported by the National Science Foundation under Award No. DMR-1120296 and the support of Award No. KUS-C1-018-02 made by the King Abdullah University of Science and Technology (KAUST). The authors also gratefully acknowledge the International Campus on Safety and Intermodality in Transportation (CISIT, France), the Nord-Pas-de-Calais Region (France), and the European Community (FEDER funds) for providing the funds for the dynamic mechanical analyzer.
PublisherAmerican Chemical Society (ACS)