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Abstract
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The objective of this study was the synthesis of
copolymer networks based on poly (ε-caprolactone) (PCL),
hydroxypropyl cellulose (HPC) and hexamethylene
diisocyanate (HDI) via bulk graft copolymerization followed
by crosslinking (using routes I and II), and subsequent optimization of the process by response surface methodology
(RSM). The studied reaction parameters were: (i) monomer
content (weight ratio of CL/HPC), (ii) amount of catalyst, and
(iii) amount of crosslinker. FT-IR and 1H NMR results confirmed that the grafting of PCL onto HPC and subsequent
crosslinking through terminal hydroxyl groups of PCL grafts
by HDI were performed successfully. Through differential
scanning calorimetry (DSC) and X-ray diffraction analysis
(XRD), it was found that the crystallinity of grafted polymers
depended on the amount of grafted PCL and degree of
crosslinking. In modeling of the process using RSM, the coefficient of determination (R2) for the models (97.3 and
93.3 % for two routes) as well as the probability (p<0.0001)
revealed high significance of the regression models. Also it
was found that the obtained systems possessed Tms between
42.94 and 54.57 °C (route I) and 32.49–46.30 °C (route II)
that were tunable by the monomer content, catalyst and
crosslinker amounts. RSM provided a useful tool to select in
a fast way the proper experimental conditions to synthesize crossinked HPC-g-PCL copolymer as a novel biocompatible
and biodegradable shape memory polymer with adjustable
switching temperature and potential biomedical applications,
which would be further studied in the future.
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