Organic Catalysis for Ring-Opening Graft Polymerization of p-Dioxanone with Xylan in Ionic liquid

Abstract

Abstract:Recently, organic catalysis has become a powerful alternative to the use of more traditional metal-based catalysts. In this study, 4-dimethylaminopyridine (DMAP), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were applied to mediate the ring-opening graft polymerization (ROGP) of p-dioxanone (PDO) with xylan-based hemicelluloses in ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). Excellent control of the molar ratio of the catalyst to anhydroxylose units (AXU) in xylan was found for a good tuning of the weight percent gain (WPG) of xylan-graft-poly(p-dioxanone) (xylan-g-PPDO) copolymers. As a result, the maximum WPG of xylan-g-PPDO copolymers was 431.07% (DMAP/AXU of 2/1), 316.72% (DBU/AXU of 0.2/1), and 323.15% (TBD/AXU of 0.2/1), respectively. The structure of xylan-g-PPDO copolymers was characterized with FT-IR and NMR. The thermal properties of copolymers were investigated using thermogravimetric analysis (TGA/DTG) and differential scanning calorimetry (DSC), and a significant difference was observed regarding the transition temperature (T g ), melting temperature (T m ), and crystallization temperature (T c ).

Synthesis and Characterization of Hydrophobically Modified Xylans

“…The FT-IR spectra of xylan and xylan-AKD adducts are shown in Figure 2 . The xylan spectrum ( Figure 2 a) was similar to what were published earlier [ 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ]. The broad feature at around 3400 cm −1 was due to O–H stretching, and the 2910 cm −1 peak to C–H vibrations.…”

“…The weak peak at ca. 1640 cm −1 was caused by residual water in the sample [ 67 , 70 ]. The 1460 cm −1 peak came from CH and OH bending in xylan [ 67 , 69 ].…”

“…1640 cm −1 was caused by residual water in the sample [ 67 , 70 ]. The 1460 cm −1 peak came from CH and OH bending in xylan [ 67 , 69 ]. The large peak at 1043 cm −1 was attributed to C–O stretching in C–O–C linkages [ 65 , 67 ].…”

“…The 1460 cm −1 peak came from CH and OH bending in xylan [ 67 , 69 ]. The large peak at 1043 cm −1 was attributed to C–O stretching in C–O–C linkages [ 65 , 67 ]. The peak at 901 cm −1 corresponded to C1–H bending and ring frequency modes in β-glycosidic linkages between the xylose units [ 66 , 69 , 70 ].…”

Preparation and Application of Phosphorylated Xylan as a Flocculant for Cationic Ethyl Violet Dye

“…The absorption peak at 2928 cm −1 was assigned to the symmetric C–H stretching vibration, and that at 1648 cm −1 contributed to the absorbed water in the samples [ 32 ]. The strong peak at 1042 cm −1 was assigned to C–O stretching in C–O–C linkages [ 33 , 34 ]. The sharp peak at 895 cm −1 was assigned to the β-glucosidic linkage between the xylose units, indicating that the xylose residues were linked by β-form bonds [ 35 ].…”