@Article{JRM.2014.634140,
AUTHOR = {Shunjie Liu, Yusheng Qin, Xianhong Wang, Fosong Wang},
TITLE = {Bulk CO<sub>2</sub>-based Amorphous Triols Used for Designing  Biocompatible Shape-Memory Polyurethanes},
JOURNAL = {Journal of Renewable Materials},
VOLUME = {3},
YEAR = {2015},
NUMBER = {2},
PAGES = {101--112},
URL = {http://www.techscience.com/jrm/v3n2/49606},
ISSN = {2164-6341},
ABSTRACT = {Precursors with sharp crystalline transition temperature have attracted signifi cant attention in the fi eld of 
shape-memory materials; however, seldom have reports been related to amorphous ones with industrial 
application prospects. This study introduced a new family of amorphous CO<sub>2</sub>
-based hydroxyl-telechelic 
three-armed oligo(carbonate-ether) triol (Triol) with controllable molecular weight (M<sub>n</sub>) and carbonate unit 
content (CU), which was coupled with PEG and 1,6-hexamethylene diisocyanate (HDI) to afford crosslinked 
polyurethanes (PU) networks with well-defi ned architecture. A crosslinking point was provided by Triol 
and PEG was used to afford networks some crystallinity. The resulting networks were characterized using 
attentuated total refl ectance Fourier transform infrared spectroscopy (ATR-FTIR) and differential scanning 
calorimetry (DSC), and the shape-memory effect test provided insight into the relationship between shape 
memory behaviors and polymeric structures. The networks displayed good dual-shape memory effect when 
compared with others: shape fi xity ratio (R<sub>f</sub>
) could be controlled by changing the Triol content and M<sub>n'</sub> and 
all the shape recovery ratios (R<sub>r</sub>
) of the networks could unexpectedly approach 100% under the experimental 
conditions. Interestingly, the substructure of the Triol CU, could effectively regulate the recovery time of 
the networks, e.g., the recovery time decreased with the increment of Triol CU without changing R<sub>f</sub>
 and R<sub>r</sub>
. 
Besides, crystalline transition temperature could be simply changed by altering Triol content. A typical sample 
Triol(2k, 50%)<sub>40</sub>-PEG(6k)<sub>60</sub> displayed excellent dual-shape effect with almost 100% R<sub>f</sub>
 and R<sub>r</sub>
 at a recovery time 
of 40 s at 70o
C. More interestingly, this sample could almost immediately recover its original shape (in less 
than 3 s) when immersed in 70o
C water. Direct contact and MTT tests were used for assessment of cell viability 
and proliferation. These results confi rmed the potential of these polyurethanes as a new family of tunable 
biomedical shape-memory materials.},
DOI = {10.7569/JRM.2014.634140}
}