Department of Orthopedics and Physical Rehabilitation
Biomaterials | Biomechanics and Biotransport | Biotechnology | Materials Chemistry | Medical Biotechnology | Molecular, Cellular, and Tissue Engineering | Orthopedics | Polymer Chemistry
Maintaining adequate or enhancing mechanical properties of shape memory polymers (SMPs) after shape recovery in an aqueous environment are greatly desired for biomedical applications of SMPs as self-fitting tissue scaffolds or minimally invasive surgical implants. Here we report stable temporary shape fixing and facile shape recovery of biodegradable triblock amphiphilic SMPs containing a poly(ethylene glycol) (PEG) center block and flanking poly(lactic acid) or poly(lactic-co-glycolic acid) blocks in warm water, accompanied by concomitant enhanced mechanical strengths. Differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WXRD), and small-angle X-ray scattering (SAXS) analyses revealed that the unique stiffening of the amphiphilic SMPs upon hydration was due to hydration-driven microphase separation and PEG crystallization. We further demonstrated that the chemical composition of degradable blocks in these SMPs could be tailored to affect the persistence of hydration-induced stiffening upon subsequent dehydration. These properties combined open new horizons for these amphiphilic SMPs for smart weight-bearing in vivo applications (e.g., as self-fitting intervertebral discs). This study also provides a new material design strategy to strengthen polymers in aqueous environment in general.
amphiphilic biodegradable polymers, hydration-induced stiffening effect, minimal invasive surgery, shape memory, weight-bearing implantation
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This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Citation: ACS Appl Mater Interfaces. 2017 Feb 8;9(5):4450-4456.10.1021/acsami.6b14167. Epub 2017 Jan 26. Link to article on publisher's site
ACS applied materials and interfaces
Zhang, Ben; DeBartolo, Janae E.; and Song, Jie, "Shape Recovery with Concomitant Mechanical Strengthening of Amphiphilic Shape Memory Polymers in Warm Water" (2017). University of Massachusetts Medical School Faculty Publications. 1267.
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