Pla 2002d

The polymer PLA2002D was obtained from NatureWorks^® Ingeo™ (Minnetonka, MN, USA); its weight average molecular weight (MW) was about 120 kg·mol⁻¹. Orotic acid (Figure 1) was from Sigma-Aldrich (St. Louis, MO, USA). It was in the form of fine powder, the grains were of uneven shape, where the majority of particle sizes was in the interval from 7 to 30 µm. The distribution of the particle cross-section arreas was evaluated with optical microscopy using ImageJ 1.5 software (Wayne Rasband, National Institutes of Health, Bethesda, MD, USA) (Figure S1 in Supplementary Materials). OA has melting point of about 345 °C so it was still solid at the processing temperature. First, PLA masterbatch with 5% (w/w) of OA was prepared by melting and mixing the components in the two-screw laboratory mini-extruder DSM Xplore 15 (Xplore Instruments BV, Sittard, The Netherlands) at 190 °C for 5 min. Then materials containing 0.1, 0.3 and 0.5% (w/w) of OA were prepared under the same conditions by mixing the masterbatch and neat PLA. Finally, the materials were dried in the vacuum oven at 60 °C for 24 h. Sample films about 100 µm thick were prepared by compression molding at 180 °C and 20 MPa for 1 min. Then the hot plates were removed from the press and let to cool down slowly on air for about 2 h.

PLA (2002D, 2,000,000 g/mol, density 1.24 g/cm³) was obtained from Natureworks. PTMC (three-armed methacrylate-ended, M_n 10,000 g/mol) macromer was synthesized as previously reported.40 Chloroform, dimethylformamide (DMF), methanol, dichloromethane, ethyl acetate, acidic acid, tetrahydrofuran (THF), and acetonitrile (high-performance liquid chromatography [HPLC] grade) were obtained from Fisher Scientific. Poly(ethylene glycol) methacrylate (average M_n360 g/mol), dexamethasone (Dexa), 2-Hydroxy-4′-(2-hydroxyethoxy)–2-methylpropiophenone (Irgacure 2959, I2959), and triethylamine were purchased from Sigma-Aldrich. Icaritin was obtained from Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences. PBS was prepared by dissolving one tablet (Sigma-Aldrich) in 200 mL deionized (DI) water. All materials and reagents were used as received.

PLA 2002D (semi-crystalline grade) was supplied by NatureWorks, Blair, NE, USA. PLA was stored in a dry, cool, and dark place before processing. Molecular weight distribution was determined by means of Gel Permeation Chromatography (GPC). An organomodified montmorillonite (MMT)-type Cloisite30B (C30B) was supplied by Southern Clay Products Inc. located in Gonzales, TX, USA and was used as filler. According to the manufacturer, the C30B was obtained by a modification of the natural MMT with a quaternary ammonium salt.

PLA (2002D) was supplied by NatureWorks (Minnetonka, MN, USA) while high molecular weight chitosan, acetone (Ac), chloroforms (TCM), and glacial acetic acid (AA) were purchased from Sigma Aldrich (Saint Louis, MO, USA).

The polylactic acid (PLA) used in this work is a commercial extrusion sheet grade supplied by NatureWorks (Nebraska, USA, named PLA 2002D) with average number molecular weight of about 121,000 g/mol, a ratio 96% L-lactide to 4% D-lactide units, and a melt flow index 6 g/10 min (230 °C, 2.16 Kg). Prior to processing, PLA pellets were dried at 70 °C under a vacuum overnight.
Two different kinds of rose flower particles, coming from Bulgarian Rosa Damascena Mill., specifically, dry rose flower (DRF) and rose flower waste (RFW), were used in this work to prepare composites based on PLA. Dry rose flower was obtained by subjecting fresh roses to natural drying for 1 month (no direct sunlight) to eliminate gradually contained water molecules and was then subjected to manual milling, obtaining particles with dimensions ca. 450 ± 51 μm. Rose flower waste (RFW) is the residual flower part after essential oil extraction at industrial level. Obtained RFW was subjected to natural drying for 1 month (no direct sunlight) to eliminate gradually contained water molecules and then was subjected to manual milling, obtaining particles with dimensions ca. 475 ± 53 μm.