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Demonstrating the mechanism and efficacy of water‐induced shape memory and the influence of water on the thermal properties of oriented poly(d,l‐lactide)
Author(s) -
Paakinaho Kaarlo,
Hukka Terttu Inkeri,
Kastinen Tuuva,
Kellomäki Minna
Publication year - 2013
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.39513
Subject(s) - shape memory polymer , materials science , glass transition , aqueous solution , polymer , chemical engineering , intermolecular force , shape memory alloy , composite material , hydrogen bond , lactide , molecule , chemistry , organic chemistry , engineering , polymerization
Achieving water‐induced shape‐memory property in poly( D,L ‐lactide) (PDLLA), generated by means of advanced processing methods, opens possibilities to develop novel bioresorbable medical devices with shape‐memory properties activated by the human body without external heat. The main phenomena that affect the molecular movements that enable the water‐induced shape‐memory effect in an oriented PDLLA in an aqueous environment at physiological temperature are related to the water driven disruption of the intermolecular dipole‐dipole and/or hydrogen bonding of the oriented PDLLA chains and the subsequent decrease of the glass transition temperature ( T g ) to the range of physiological temperature. The diffused water in the polymer matrix decreased the energy needed to finish the glass transition process explaining the higher shape‐recovery rate of the γ‐irradiated PDLLA with respect to the non‐γ‐irradiated PDLLA in an aqueous environment at physiological temperatures. The water‐induced decrease in the T g was thermally reversible. The efficacy of the generated shape‐memory was tested with PDLLA shape‐memory nails in a pullout test, in which the pullout force of the PDLLA nails increased 360% during a seven day test period in vitro at 37°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4209–4218, 2013