Ingeo biopolymer 4032d

Experiments were carried out on nanofibrous membranes made of a PLGA copolymer (ratio 85:15, Purasorb^® PLG 8531; Corbion, Amsterdam, the Netherlands) or made of PLA (Ingeo™ Biopolymer 4032D; NatureWorks, Minnetonka, MN, USA). The solution for the polymers was prepared and the electrospinning process carried out as presented in our previous work.9 (link) Both polymers were dissolved in chloroform. Solvents – dichloroethane and ethyl acetate – were added into a PLA solution to a final concentration of 7 wt% of PLA. The volume ratio of the chloroform, dichloroethane, and ethyl acetate solvents was 61:29:10. The solution of the two polymers was made electrically conductive with the use of tetraethylammonium bromide. This chemical was first dissolved in dimethylformamide to a concentration of 3 wt%. Then, 3 g of this solution was added to 100 g of the PLGA or PLA solution.
Nanospider needle-free electrospinning technology (Elmarco, Liberec, Czech Republic) was used for preparing the nanofibrous membranes. The process conditions were electrode distance 145–180 mm, voltage 50–60 kV, relative humidity 20%–30%, and room temperature. Fiber density, ie, the area weight of the prepared nanofibers, was 10.5–19.6 g/m² for PLGA and 13–15 g/m² for PLA. The thickness of the membranes was in the range of 47–97 μm for PLGA and 125–190 μm for PLA.9 (link)

Poly(l-lactide) (PLA; Ingeo™ Biopolymer 4032D) was purchased from NatureWorks, Minnetonka, MN, USA. The molecular parameters of the polymer material, determined by size exclusion chromatography, were M_w=124,000 g/mol and M_n=48,000 g/mol.39 (link) A 7 wt% solution of PLA in a mixture of chloroform, dichloroethane, and ethyl acetate in the volume ratio of 61:29:10 was used for the electrospinning process. The polymer was diluted only in chloroform, and the other two solvents were added after the dilution. The polymer solution was made electrically conductive with the use of tetraethylammonium bromide, which was first dissolved in dimethylformamide at a concentration of 3 wt%, and then 3 g of this solution was added to 100 g of the PLA solution.40 (link)
Nanofibrous membranes were prepared using the novel Nanospider needleless electrospinning technology (NS Lab 500; Elmarco Ltd., Liberec, Czech Republic). The process conditions were: electrode distance: 180 mm; voltage: 60–10 kV; the spinning electrode rotated at 4 rpm; relative humidity: 25%–30%, and room temperature. The fiber density, ie, the area weight of the prepared nanofibers, was from 12 to 15 g/m².