Determination of propagation rate coefficients for an ?-substituted acrylic ester: Pulsed laser polymerization of dimethyl itaconate

Abstract

Pulsed laser polymerization experiments have been performed on the bulk polymerization of dimethyl itaconate over the temperature range 20–50 °C. The activation energy and frequency factor were calculated as 24.9 kJ/mol−1 and 2.15 × 105 L/mol−1s−1, respectively. The activation energy is comparable with the methacrylate series of monomers. The frequency factor is relatively small and reflects steric hindrance in the transition state caused by the bulky 1,1, disubstitution in the monomer (and consequently the radical). The Mark–Houwink–Kuhn–Sakurada constants were also determined for poly(dimethyl itaconate) in tetrahydrofuran, these are reported as 46 × 10−5 dL/g (K) and 0.51 (α). The influence of penultimate units (γ‐substituents) on homopropagation reactions is discussed particularly for polymerizations leading to significant 1,3 interactions in the resultant polymer. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2192–2200, 2000

Ambient temperature synthesis of well‐defined microspheres via precipitation polymerization initiated by UV‐irradiation

“…In the present study we employ an azotype photo initiator (AIBN), which--at temperatures exceeding 35 8C--also provides an extremely small radical flux via thermal decomposition; yet this almost negligible flux does not significantly interfere with its photo initiating ability as documented in its frequent use in low temperature pulse laser polymerization experiments. 16 We further employ two acetophenone type initiators (i.e., DMPA and MMMP).…”

Solvent effects on free-radical copolymerization of styrene and 2-hydroxyethyl methacrylate: a DFT study

“…Later, Klumperman and O'Driscoll 19 proposed a partition coefficient (k) as the ratio between the monomer concentration in the vicinity of the growing chain radicals (local concentration) and in the solution (global concentration), thus quantifying the partitioning phenomena described by Harwood. Experimental studies of solvent effects on copolymerization kinetics involve measuring propagation rate coefficients via the pulsed laser polymerization (PLP) technique. [20][21][22][23][24][25][26][27] Solvent effects on the propagation of methacrylic acid (MAA) are studied via PLP and specific monomer-solvent interactions are investigated using FTIR spectroscopy. 28 Propagation rate constants of acrylic acid (AA) and MAA in water are significantly influenced by organic solvents and changing monomer concentrations.…”

Reversible addition fragmentation chain transfer polymerization of sterically hindered monomers: Toward well‐defined rod/coil architectures

“…The bulky groups in the vicinity of the vinyl functionality prevent the propagating radical to effectively react with monomer, so that the propagation rate, k p , and termination rate coefficient, k t , are significantly lower than those of more common monomer systems under comparable reaction conditions [e.g., k p (methyl acrylate, 60 °C) = 27,000 L mol −1 s −1 , 〈 k t 〉(methyl acrylate, 60 °C) = 1·10 8 L mol −1 s −1 , k p (DCHI, 60 °C) = 6.0 L mol −1 s −1 , 〈 k t 〉(DCHI, 60 °C) = 1403 L mol −1 s −1 ] 19–23. The relatively low termination rate coefficients observed for hindered monomer systems leads to the generation of relatively high radical concentrations in the respective polymerization mixtures, making them ideal candidates to be studied via electron spin resonance spectroscopy (see Ref.…”