Synthesis and Mechanism of Metal-Mediated Polymerization of Phenolic Resins
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Ministry of Education (MOE) Key Laboratory of Wooden Material Science and Application, Beijing Key Laboratory of Wood Science and Engineering, School of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China
2
Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (MOE), School of Materials Science and Engineering, Shandong University, Jinan 250061, China
*
Authors to whom correspondence should be addressed.
Academic Editor: Antonio Pizzi
Polymers 2016, 8(5), 159; https://doi.org/10.3390/polym8050159
Received: 4 March 2016
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Revised: 14 April 2016
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Accepted: 15 April 2016
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Published: 26 April 2016
(This article belongs to the Special Issue Renewable Polymeric Adhesives)
Phenol-formaldehyde (PF) resin is a high performance adhesive, but has not been widely developed due to its slow curing rate and high curing temperature. To accelerate the curing rate and to lower the curing temperature of PF resin, four types of metal-mediated catalysts were employed in the synthesis of PF resin; namely, barium hydroxide (Ba(OH)2), sodium carbonate (Na2CO3), lithium hydroxide (LiOH), and zinc acetate ((CH3COO)2Zn). The cure-acceleration effects of these catalysts on the properties of PF resins were measured, and the chemical structures of the PF resins accelerated with the catalysts were investigated by using Fourier transform infrared (FT-IR) spectroscopy and quantitative liquid carbon-13 nuclear magnetic resonance (13C NMR). The results showed that the accelerated efficiency of these catalysts to PF resin could be ordered in the following sequence: Na2CO3 > (CH3COO)2Zn > Ba(OH)2 > LiOH. The catalysts (CH3COO)2Zn and Na2CO3 increased the reaction activity of the phenol ortho position and the condensation reaction of ortho methylol. The accelerating mechanism of (CH3COO)2Zn on PF resin is probably different from that of Na2CO3, which can be confirmed by the differences in the differential thermogravimetric (DTG) curve and thermogravimetric (TG) data. Compared to the Na2CO3-accelerated PF resin, the (CH3COO)2Zn-accelerated PF resin showed different peaks in the DTG curve and higher weight residues. In the synthesis process, the catalyst (CH3COO)2Zn may form chelating compounds (containing a metal-ligand bond), which can promote the linkage of formaldehyde to the phenolic hydroxyl ortho position.
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MDPI and ACS Style
Yi, Z.; Zhang, J.; Zhang, S.; Gao, Q.; Li, J.; Zhang, W. Synthesis and Mechanism of Metal-Mediated Polymerization of Phenolic Resins. Polymers 2016, 8, 159. https://doi.org/10.3390/polym8050159
AMA Style
Yi Z, Zhang J, Zhang S, Gao Q, Li J, Zhang W. Synthesis and Mechanism of Metal-Mediated Polymerization of Phenolic Resins. Polymers. 2016; 8(5):159. https://doi.org/10.3390/polym8050159
Chicago/Turabian StyleYi, Zhao, Jizhi Zhang, Shifeng Zhang, Qiang Gao, Jianzhang Li, and Wei Zhang. 2016. "Synthesis and Mechanism of Metal-Mediated Polymerization of Phenolic Resins" Polymers 8, no. 5: 159. https://doi.org/10.3390/polym8050159
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