Bentonite clay nanoparticles without surface modification were used to prepare a polymer-based nanocomposite: Butyl acrylate (BA), methyl methacrylate (MMA), and acrylic acid (AA) were copolymerized as the matrix. The synthesis was carried out using seeded batch emulsion polymerization system. Bentonite was added up to 3 wt% and the metastable emulsions remained for a period over 6 months in storage at room temperature, to estimate the emulsion stability. Cast films were obtained from the aqueous dispersions and these were optically transparent. Scanning electron microscopy and X-ray scattering spectra showed that the copolymer chain had intercalated the Bentonite nanoplatelets, with aggregates into small crystalline clusters and dispersed through the polymer matrix. Differential scanning calorimetry showed that increasing the concentration of Bentonite increased the glass transition temperature, T g . Furthermore, uniaxial tensile deformation at room temperature showed that the elastic Youngs modulus, E, increased over an order of magnitude at 3 wt% Bentonite concentration. These results suggest that the molecular dynamics is inhibited, due to the associated restricted motions of the confined macromolecules within the gallery clay and the increment of the molecular weight. POLYM. COMPOS., 00:000-000, 2017. V C 2017 Society of Plastics Engineers FIG. 2. Solids analysis obtained as a function of polymerization time for (i) copolymer and the nanocomposites containing (a) 1 wt%, (b) 2 wt%, and (c) 3 wt% bentonite. Lines are only intended as guide to the eye. FIG. 3. Degree of conversion and coagulum amount of polymer/clay emulsions as a function of bentonite concentration. Lines are only intended as guide to the eye. FIG. 7. Photographs of copolymer/bentonite nanocomposites, about 1.0, 0.4, 0.2, and 0.5 mm in thickness, casted from their respective emulsions. The concentrations of bentonite are (a) 0 wt%, (b) 1 wt%, (c) 2 wt%, and (d) 3 wt%. FIG. 12. (a) TGA and (b) DTG curves for (i) copolymer and nanocomposites containing (ii) 1 wt%, (iii) 2 wt%, and (iv) 3 wt% of bentonite.

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Advances in tissue engineering have made possible the construction of organs and tissues with the use of biomaterials and cells. Three important elements are considered: a specific cell culture, an adequate environment, and a scaffold. The present study aimed to develop P3HB scaffolds by 3D printing and evaluate their biocompatibility with HaCaT epidermal cells, as a potential model that allows the formation of functional tissue. By using a method of extraction and purification with ethanol and acetone, a biopolymer having suitable properties for use as a tissue support was obtained. This polymer exhibited a higher molecular weight (1500 kDa) and lower contact angle (less than 90°) compared to the material obtained using the conventional method. The biocompatibility analysis reveals that the scaffold obtained using the ethanol–acetone method and produced by 3D printing without pores was not cytotoxic, did not self-degrade, and allowed high homogenous cell proliferation of HaCaT cells. In summary, it is possible to conclude that the P3HB scaffold obtained by 3D printing and a simplified extraction method is a suitable support for the homogeneous development of HaCaT keratinocyte cell lineage, which would allow the evaluation of this material to be used as a biomatrix for tissue engineering.

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