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It was necessary to study the bonding mechanism of poly(D,L-lactide) (PDLLA) and hydroxyapatite (HA) nanoparticles because of their increasing application in medical fields. In this paper, hydrogen bonding between PDLLA and HA in PDLLA/HA nanocomposites was first investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Structural morphology and glass transition temperature (T g ) of the nanocomposites showed that there was a close interaction between polymer matrix and inorganic nanoparticls. The results from FTIR and XPS indicated that the hydrogen bonding between the CdO in PDLLA and the surface PsOH groups of HA nanocrystalline was formed indeed. Shape memory properties were improved, which further implied the existence of hydrogen bonding in these nanocomposites. Thus, we designed a schematic model of the hydrogen bonding on the base of the experimental results. It can clearly explain the interaction mechanism of polymeric phases and inorganic phase in nanocomposites.

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In this study, we developed a thermoresponsive and water-responsive shape-memory polymer nanocomposite network by chemically cross-linking cellulose nanocrystals (CNCs) with polycaprolactone (PCL) and polyethylene glycol (PEG). The nanocomposite network was fully characterized, including the microstructure, cross-link density, water contact angle, water uptake, crystallinity, thermal properties, and static and dynamic mechanical properties. We found that the PEG[60]-PCL[40]-CNC[10] nanocomposite exhibited excellent thermo-induced and water-induced shape-memory effects in water at 37 °C (close to body temperature), and the introduction of CNC clearly improved the mechanical properties of the mixture of both PEG and PCL polymers with low molecular weights. In addition, Alamar blue assays based on osteoblasts indicated that the nanocomposites possessed good cytocompatibility. Therefore, this thermoresponsive and water-responsive shape-memory nanocomposite could be potentially developed into a new smart biomaterial.