Polymerization Of P-methylstyrene Research Articles

Mechanism for initiation cation polymerization of p-methylstyrene in the presence of BF3∙HF catalyst in toluene at 1:4 ratio

Mechanism for initiation cation polymerization of p-methylstyrene in the presence of BF3∙HF catalyst in toluene at 1:4 ratio

Preparation of 20-nm poly(styrene derivative) particles via polymerization with nonionic surfactant at the phase-inversion temperature

Several types of styrene monomer derivatives were polymerized in monomer, water, polyoxyethylene alkyl phenyl ether and initiator mixtures at various temperatures to form small particles. Smaller particles were obtained at higher radical generation rates at the phase-inversion temperature (PIT). Large coagula or secondary particles were obtained at temperatures higher than the PIT. The average diameter of the polymer particles obtained via the polymerization of p-methylstyrene and styrene at the PIT was smaller than those of divinylbenzene and 4-t-butylstyrene. Poly(p-methylstyrene) particles, which had an average diameter of 21 nm and a polymer weight fraction of 5%, were prepared. Poly(styrene derivative) particles, average diameter of which is <30nm, were prepared without ionic emulsifier with nonionic emulsifier polyoxyethylene alkyl phenyl ether by polymerizing monomer, emulsifier, water and initiator mixture at around PIT. Effects of initiator concentration, temperature and monomer type on the average diameter of the generated polymer particles are investigated. Smaller particles are obtained with higher rate of radical generation at PIT. The particles of poly(p-methylstyrene) which have an average diameter of 21 nm and a polymer weight fraction of 5% were prepared.

Effect of temperature on tacticity in thermal polymerization of p-methylstyrene by 13C NMR spectroscopy

Poly(p-methylstyrene) (Pp-MS) was synthesized at three different temperatures of 50, 150 and 250 °C via bulk thermal polymerization method. The assignment of all stereosequences at triad and pentad levels for two quaternary aromatic carbons and hexad level for methylene carbon was carried out by 13C liquid nuclear magnetic resonance spectroscopy (NMR) in deuterated chloroform at similar conditions. The probability of meso addition (P m) was calculated from second quaternary aromatic carbon and used to predict the relative intensities of methylene and first quaternary aromatic carbon by Bernoullian and first-order Markov statistical models. The results were compared with experimental data. It is shown that the Bernoullian statistics fit better than first-order Markov model for all three samples. The results indicate that P m increases by increasing polymerization temperature. The corresponding P m values determined for synthesized Pp-MSs at 50, 150 and 250 °C were 0.383, 0.392 and 0.404, respectively. It was observed that higher resolutions and better splitting patterns were achievable by increasing the NMR acquisition temperature from 20 to 50 °C. When temperature increased during NMR acquisition, the resolution improved for the first and second quaternary aromatic carbons and methylene carbon, though there was no splitting pattern observed for methyl carbon atom at the para-position of the aromatic ring.

Structure−Reactivity Scales in Carbocationic Polymerizations

The polymerization of p-methylstyrene (pMeSt) in the presence of isobutylene (IB), styrene (St), p-chlorostyrene (pClSt), and 1,3-butadiene (BD) was carried out at -40 °C. By selecting CH 2 Cl 2 /methylcyclohexane (MeCHx) 50/50 (v/v) solvent mixture and the appropriate weak Lewis acid, SnBr 2 Cl 2 monoaddition of IB, St, pClSt, and BD followed by instantaneous termination was achieved, and the polymerizations stopped short of completion. The reactivity ratios, k p /k 12 , where kp is propagation rate constant and k 12 is the cross-propagation rate constant, were calculated on the basis of limiting conversions and limiting molecular weights. According to these values, pMeSt is 3.8 ± 0.5, 4.8 ± 1.1, 7.2 ± 1.6, and 100 ± 6 times more reactive than IB, St, pClSt, and BD respectively. Similar competition reactions between IB/BD, St/BD. and pClSt/BD in conjunction with TiCl 4 as Lewis acid yielded k p /k 12 = 77 ± 5, 7.1 ± 1.0, and 3.2 ± 0.7, respectively. Using k p /k 12 and k p forpMeSt, St, and pClSt, the cross-propagation k 12 values were calculated to establish structure-reactivity scales. Similarly to our earlier observations, comparison of these values indicated that structural differences have a much larger effect on cation reactivity than on monomer reactivity.

Photoinitiated Cationic Polymerization of p-methylstyrene by Methoxy Trityl Salts

Photoinitiated cationic polymerization of p-methylstyrene has been investigated in dichloromethane at 25°C, using stable, soluble, and nonhygroscopic di, tri and pentamethoxy trityl carbocationic salts, having non-nucleophilic anions such as SbF6 −, AsF6 −, PF6 −. The reactivity of these salts falls in the order: trimethoxy > dimethoxy > pentamethoxy. The effects of counter ion structure, salt concentration, photolysis time and photolysis wavelength on the polymerization rate are presented.

Living Carbocationic Polymerization of P-Methylstyrene and Sequential Block Copolymerization of Isobutylene with P-Methylstyrene

Living Carbocationic Polymerization of P-Methylstyrene and Sequential Block Copolymerization of Isobutylene with P-Methylstyrene

Cationic polymerization of p-methylstyrene initiated by acetyl perchlorate: An approach to living polymerization

Cationic polymerization of p-methylstyrene initiated by acetyl perchlorate: An approach to living polymerization