The desirable properties of polyurethanes (PUs) such as mechanical flexibility
associated with chemical versatility make these polymers attractive in the
development of biomedical devices. In this study, various segmented
polyurethanes were synthesized through polymerization reactions between
polycaprolactone (PCL) diol or triol and excess hexamethylene diisocyanate
(HDI) with varying NCO/OH ratios and the effect of composition on the
properties of the resultant polyurethane films were examined. Initially, isocyanate
terminated prepolymers were synthesized through one-shot polymerization, and
then these prepolymers were cured by introducing crosslinkages into the structure
and thus PUs were obtained. In order to enhance biocompatibility and
hydrophilicity of the resulting polymers, heparin was added into the prepolymer before the curing process. The influence of excess HDI as a crosslinker on the
degree of H-bond formation between hard-hard segments or hard-soft segments
was examined by using Fourier transform infrared-Attenuated total reflectance
spectroscopy (FTIR-ATR). Also the effects of HDI content on the chemical,
physical and mechanical properties of the polyurethanes were examined with
differential scanning calorimetry (DSC), X-Ray diffraction spectroscopy (XRD),
dynamic mechanical analyzer (DMA), mechanical tester and goniometer. FTIR-
ATR, DSC and DMA analyses showed that use of triol resulted in better network
formation and homogenous distribution of hard segments within soft segment
matrix. Incorporation of heparin into the polymer matrix produced more
hydrophilic films (water contact angle reduced from 80 to 60). Polyurethanes
from PCL and HDI in the absence of any solvent, initiator, catalyst or chain
extender were successfully synthesized and this kind of synthesis enhanced
biocompatibility and increased the potential of polymers for use in biomedical
applications.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12614253/index.pdf |
| Date | 01 March 2012 |
| Creators | Guney, Aysun |
| Contributors | Hasirci, Nesrin |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | Access forbidden for 1 year |
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