Abstract
Achieving an efficient catalyst in the ATRP system with a simple design, preparation from available materials, and high recyclability is a significant challenging issue. To attain the goal, herein, we used chitosan (CS)-modified cellulose filter paper (FP) as a green support for the synthesis of dip catalyst. The preparation of this catalyst involved surface treatment of the FP strips by CS coating through a dipping method, which increased the affinity of the substrate for adsorbing copper ions in the next step. The Cu@CS-FP catalyst was prepared without the requirement of any ligands. The synthesized dip-catalyst, in the form of the strips, was employed for the first time in the ATRP reaction of methyl methacrylate to assay catalytic activity. Catalytic insertion/ removal (ON/OFF) experiments were carried out during the polymerization. A reasonable control over the molecular weight with high conversion (68%) and polydispersity index of 1.32 under mild reaction conditions were obtained. Significantly, because of the facile separation of the catalyst, the amount of copper that remained in the polymer was very low (2.7 ppm). Also, the recyclability of the catalyst was investigated for five runs. The conversion in the final run was 64% without a loss of catalyst efficiency.
Highlights
Achieving an efficient catalyst in the atom transfer radical polymerization (ATRP) system with a simple design, preparation from available materials, and high recyclability is a significant challenging issue
We studied samples through elemental analysis and Energy Dispersive X-ray analysis (EDX) mapping analysis to further confirm the successful formation of dip catalyst, and distribution of copper and CS onto the filter paper (FP) cellulose microfibers
We successfully prepared a recoverable dip catalyst based on CS-FP for ATRP reaction
Summary
The results showed that increasing the duration leads to low conversion and high molecular weight distribution (Table 1, Run[6,7]). The comparison of the prepared catalyst for the ATRP reaction of methyl methacrylate with previously reported copper-based catalysts, respect to the initiator, solvent, reaction time, conversion percentage, and molecular weight distribution, have been provided (Table 2). ATRP of MMA using 3-bromo-3-methyl-butanone-2 (MBB) as an initiator in the presence of CuBr and different ligands as a catalyst in toluene solvent at 90 °C was presented according to previous researches (Table 2, Run 2–7). The copper (I) with 2,6-bis(4,4-dimethyl-2-oxazolin-2-yl)pyridine (dmPYBOX) was formed a more stable complex but disturbed the equilibrium dynamics of the reaction which resulted in low molecular weight (Table 2, Run 7).
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