The role of cellulose nanowhiskers in controlling phase segregation, crystallization and thermal stimuli responsiveness in PCL-PEGx-PCL block copolymer-based PU for human tissue engineering applications

Abstract In this research, two groups of polyurethane (PU) nanocomposites were developed based on PCL500-PEGx-PCL500 tri-block polyols and cellulose nanowhisker (CNW), as a cross-linker and controller of microphase separation of blocks. The effect of PEGx block length on phase segregation and crystallization of blocks was evaluated. The impact of tuned crystallization and hard domain morphology on shape memory parameters was studied in detail. PU2000-0.25% was selected as the optimum specimen with shape fixity and recovery of 100%. CNW nanorods were found to act as a controlling agent of the microphase segregation, possibly through changing the spatial organization of hard segments from a 3D self-assembled to a shell-like structure. Three different cell lines (HepG2, HFF, and mesenchymal stem cells) were used to culture on the prepared 2D specimens, resulting in different behaviors. The newly synthesized biomaterials with different cellular responses presented a great potential for a variety of tissue engineering applications.