In this work, the morphological and conformational evolution of bio-based polyethylene glycol (PEG)-acrylic rosin polymer in water was studied by scanning electron microscopy (SEM), polarized optical microscopy (POM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Rayleigh light scattering (RLS) and dynamic light scattering (DLS) techniques during a heating and cooling cycle. When the concentration was higher than the critical micelle concentration (CMC), a reversible transformation process, i.e. from micelle to irregular lamella aggregations, was detected. As the concentration was equal to or below the CMC, individual unimers aggregated into needle-shaped crystals composed of acrylic rosin crystalline core in the heating run. The crystallization of acrylic rosin blocks acted as seeds and thus, in the subsequent cooling process, the PEG corona crystallized into the cube-shaped crystals. The cytotoxicity assay showed the biocompatibility of bio-based polyethylene glycol-acrylic rosin polymer. This has great potential in the application of drug delivery and release triggered by temperature.
