Commonly used thermoplastic biodegradable polymers are generally brittle and
lack appreciable elasticity at physiological temperature and thereby fail to mimic the
elastic nature of many human soft tissues such as blood vessels. Thus, there is a need for
biomaterials which exhibit elasticity. Biodegradable elastomers are promising candidates
whose elasticity more closely parallels that of soft tissues. In this research, we developed
hybrid biodegradable elastomers comprised of organic and inorganic polymer
components in a block copolymer system: poly(e-caprolactone) (PCL) and
poly(dimethylsiloxane) (PDMS), respectively. A block structure maintains the distinct
properties of the PCL and PDMS components. These elastomers may be useful for the
tissue engineering of soft tissues as well as for shape memory polymer (SMP) devices.
Tri-block macromers of the form PCLn-block-PDMSm-block-PCLn were
developed to permit systematic variations to key features including: PDMS block length,
PCL block length, PDMS:PCL ratio, and crosslink density. The macromer was capped
with acrylating groups (AcO) to permit their photochemical cure to form elastomers.
Thus, a series of biodegradable elastomers were prepared by photocrosslinking a series of macromers in which the PCL blocks varied (n = 5, 10, 20, 30, and 40) and the PDMS
block was maintained (m = 37). All elastomers displayed hydrophobic surface properties
and high thermal stability. These elastomers demonstrated systematic tuning of
mechanical properties as a function of PCL block length or crosslink density. Notable
was strains at break as high as 814% making them suitable for elastomeric
bioapplications.
Elastomers with a critical PCL block length (n = 30 or 40) exhibited shape
memory properties. Shape memory polymers based on an organic-inorganic,
photocurable silicon-containing polymer system is a first of its kind. This SMP
demonstrated strain fixity of 100% and strain recovery near 100% after the third
thermomechanical cycle. Transition from temporary to permanent shape was quite rapid
(2 sec) and at temperatures near body temperature (60 degrees C). Lastly, porous analogues of
the biodegradable elastomers were created using a novel porogen - salt leaching
technique. Resulting porous elastomers were designed for tissue engineering scaffolds or
shape memory foams.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2009-08-854 |
| Date | 2009 August 1900 |
| Creators | Schoener, Cody A. |
| Contributors | Grunlan, Melissa |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | application/pdf |
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