Development of a semi-crystalline hybrid polyurethane nanocomposites for hMSCs cell culture and evaluation of body- temperature shape memory performance and isothermal crystallization kinetics

We report synthesis and characterization of a group of reactive in-situ polyurethane (PU) nanocomposites based on PCL1000-PEG2000-PCL1000 block copolymer- diol and MWCNT/Graphene nanoparticles. The experiments were designed to tune shape fixity (SF) and shape recovery (SR) of the specimens. Hydroxyl-functionalized MWCNTs’ content was set constant at 0.25 wt% (T0.25) and Graphene’s content was varied in the range of 0 to 0.75 wt% (G (0–0.75)) to control the crystallization of the soft segment blocks and elastic modulus of the PU nanocomposites. The pure and T0.25G0.50 showed the highest shape fixity (SF = 100%). The optimum sample was PU nanocomposite of T0.25G0.50 with an SR of 95%. The results of Dynamic Mechanical Thermal Analysis (DMTA) indicated lack of flowage for the nanocomposites and their thermoset nature. The non-isothermal crystallization analysis indicated a sharp decline in crystallization temperature (Tc) of the soft segments of T0.25G0 sample and adding graphene nanoplatelets improved the crystallization extent and increased Tc. The isothermal crystallization kinetics of the PUs indicated an increase in crystallization kinetics by increasing graphene’s content compared to T0.25G0 sample. The results of Human Mesenchymal Stem cells (hMSCs) culture indicated an increase in cell adhesion and proliferation as a function of Graphene’s content.