Kinetic study of the stable free‐radical copolymerization of styrene with butyl methacrylate

Abstract

The radical copolymerization of styrene and n-butyl methacrylate mediated by 1-phenyl-1-(2Ј,2Ј,6Ј,6Ј-tetramethyl-1Ј-piperidinyl-oxy)ethane in bulk at 125°C has been analyzed over a wide range of conversions and monomer feed compositions. Monomer reactivity ratios have been determined, and the Mayo-Lewis terminal model provides excellent predictions for the variations of the intermolecular structure over the entire conversion range. The kinetic analysis of this copolymerization system indicates an apparent propagation rate coefficient independent of the monomer feed composition as well as a limiting conversion that decreases as the styrene monomer feed decreases. This fact is attributed to side reactions leading to unsaturated end groups and the accumulation of nonactive adducts of n-butyl methacrylate. The number-average molecular weights linearly increase with conversion, and the copolymers present narrow molecular weight distributions.

Sequence Distribution and Stereoregularity in Styrene/Butyl Methacrylate Copolymers Obtained at High Conversion by Stable Free-Radical Polymerization

“…The monomer reactivity ratios, determined by the Kelen-Tüdos method modified for high conversion, [9] are r S = 0.44 l 0.02 and r B = 0.55 l 0.02. Figure 1 shows the 13 C NMR spectra of several copolymer samples prepared with different monomer feed com- positions at conversions below 15%.…”

“…Since, as stated previously, [9] MLTM can predict the copolymer composition with increasing conversion and it has been proved that it also describes the tactic triads fractions at relatively low conversion, the next step will be to predict the complete copolymer structure with increasing conversion. The effect of conversion on the stereochemical composition of copolymer chains has been approximated by a step function program.…”

“…Other experimental details were described previously. [9] Copolymer samples were dissolved in CDCl 3 and tetramethylsilane was used as an internal standard. 125 MHz 13 C NMR spectra were obtained at 50 8C with a Bruker AMX-500 spectrometer (pulse width (80 8): 7.1 ls, acquisition time: 1.05 s, 65 536 acquisition points, 31 250 spectral width, 12 000 scans, pulse delay: 4 s).…”

“…In a previous paper [9] we described the N-oxylmediated copolymerization of styrene/butyl methacrylate (S/B) performed with 2,2,6,6-tetramethyl-1-(1-phenylethoxy)piperidine (PETEMPO) at 125 8C. Kinetic analysis of this copolymerization system indicated an apparent propagation rate coefficient independent of the monomer feed composition with a limiting conversion that decreases with the S monomer feed.…”

Quality of life in systemic sclerosis: Psychometric properties of the World Health Organization Disability Assessment Schedule II

“…The following study first evaluates the NMP kinetics of various methacrylates such as MMA, ethyl methacrylate (EMA), and n ‐butyl methacrylate (BMA) in solution at 90 °C with a small amount of styrene comonomer and BlocBuilder as the unimolecular initiator. EMA and BMA have both been previously copolymerized with styrene by NMP with TEMPO using low methacrylate feed compositions but in all cases the propensity of irreversible termination reactions was apparent at low conversions (∼30%) 47–49…”