A Theoretical and Experimental Study for Screening Inhibitors for Styrene Polymerization

Abstract

Styrene is one of the most important monomers utilized in the synthesis of various polymers. Nevertheless, during distillation, storage, and transportation of ST, undesired polymer (i.e., UP) formation can take place. Thus, the control of undesired polymerization of styrene is a challenging issue facing industry. To tackle the mentioned issue, the antipolymer and antioxidant activity of stable nitroxide radicals (i.e., SNRs) and phenolics in styrene polymerization were studied by density functional theory (DFT) calculation and experimental approach. The electrophilicity index and growth percentage have been determined by DFT calculation and experimental approach, respectively. It is depicted that 2,6-di-tert-butyl-4-methoxyphenol (DTBMP) and 2,6-di-tert-butyl-4-methylphenol (BHT) from phenolics, and 4-hydroxy-2,2,6,6-tetramethyl piperidine 1-Oxyl (4-hydroxy-TEMPO) and 4-oxo-2,2,6,6-tetramethylpiperidine 1-Oxyl (4-oxo-TEMPO) from stable nitroxide radicals were the most effective inhibitors. Also, the growth percentage of DTMBP, BHT, 4-hydroxy-TEMPO, and 4-oxo-TEMPO after 4 h were 16.40, 42.50, 24.85, and 46.8, respectively. In addition, the conversion percentage of DTMBP, BHT, 4-hydroxy-TEMPO, and 4-oxo-TEMPO after 4 h were obtained to be 0.048, 0.111, 0.065, and 0.134, respectively. Furthermore, the synergistic effect of these inhibitors was investigated experimentally, indicating that DTMBP/4-hydroxy-TEMPO exerted the best synergistic effects on the inhibition of polymerization. The optimum inhibition effect was observed at the blend of 4-hydroxy-TEMPO (25 wt.%) and DTMBP (75 wt.%,) corresponding to 6.8% polymer growth after 4 h.

Cumene Hydroperoxide-Induced Epoxidation of Styrene Using Cu2O and PbO as Catalysts

“…TBC has been reported to lose its inhibition potential beyond ∼328 K . For any high-temperature operation, such as separation of styrene via distillation, other free radical inhibitors are used …”

Inhibition of Free Radical Polymerization: A Review

“…Darvishi et al studied the influence of phenolic inhibitors and their blends with the previously discussed TEMPO inhibitors on the polymerization of styrene [ 50 ]. They employed a combination of experimental and density functional theory (DFT) techniques to compare the activity of these inhibitors.…”

“…Darvishi et al performed experiments to investigate the production of dimers and oligomers, and conversion of styrene after 4 and 8 h of operation [ 50 ]. Table 5 summarizes the influence of various phenolic inhibitors on the weight of produced, undesired polymer and its growth, the mass fraction of the formed dimer and oligomer, and styrene conversion.…”

“…Darvishi et al also studied the synergistic effect of SNRs (TEMPO and its analogues) and phenolics to examine the inhibition performance [ 50 ]. They injected a blend of SNRs and phenolics (50 wt.%) in the process with 50 ppm overall concentration.…”

Special Issue on “Computational Methods for Polymers”

“…Darvishi et al [8] use electronic-scale modeling to study undesired polymerization of styrene during distillation, storage, and transportation. They apply DFT and carried out laboratory experiments to study the antipolymer and antioxidant activity of stable nitroxide radicals and phenolics in styrene polymerization.…”