Termination Kinetics of Free-Radical Methyl Methacrylate - Dodecyl Acrylate and Dodecyl Methacrylate - Methyl Acrylate Copolymerizations

2002 ◽  
Vol 55 (7) ◽  
pp. 475 ◽  
Author(s):  
M. Buback ◽  
A. Feldermann
Keyword(s):  
Methyl Methacrylate ◽  
Methyl Acrylate ◽  
Geometric Mean ◽  
Single Pulse ◽  
Monomer Conversion ◽  
Ester Group ◽  
Rate Coefficients ◽  
Diffusion Control ◽  
Monomer Composition ◽  
Dodecyl Methacrylate

Copolymerization termination rate coefficients (kt) of the methyl methacrylate–dodecyl acrylate (MMA–DA) and dodecyl methacrylate–methyl acrylate (DMA–MA) systems at 40°C and 1000 bar have been measured using the single pulse (SP)–pulsed laser polymerization (PLP) technique. Plateau regions of kt are observed in the initial polymerization period. The region of constant kt increases with the size of the alkyl ester group, e.g. it extends up to at least 60% monomer conversion in DA and DMA homopolymerizations. The plateau kt values of MA and MMA are significantly above the corresponding DA and DMA values. The kt penultimate unit effect model, which uses the so-called geometric mean approximation, is well suited for representation of the dependence on monomer composition of the plateau kt values. The dependence of kt on monomer composition is quite different at low and at high degrees of monomer conversion. The reason behind this is seen in different types of diffusion control being operative at low and at high degrees of monomer conversion. The plateau-type behaviour is assigned to segmental diffusion control, whereas high-conversion kt is controlled by reaction diffusion.

Studies in copolymerization I. The evaluation of the kinetic coefficients for the copolymerization of styrene and methyl methacrylate

1950 ◽  
Vol 200 (1062) ◽  
pp. 337-358 ◽  
Keyword(s):  
Methyl Methacrylate ◽  
Benzoyl Peroxide ◽  
Rate Coefficient ◽  
Benzene Solution ◽  
Rate Coefficients ◽  
Absolute Velocity ◽  
Monomer Composition ◽  
Kinetic Coefficients ◽  
Osmotic Behaviour ◽  
The Absolute

The benzoyl peroxide photosensitized copolymerization of styrene and methyl methacrylate has been studied with the object of determining all the rate coefficients. The variation of rate of copolymerization with monomer composition has been determined under standard conditions, the reaction being followed dilatometrically. The rate of initiation has also been studied as a function of monomer composition; it was found that the introduction of small quantities of styrene markedly lowered the rate of initiation. From a combination of these two studies, the absolute velocity coefficients for all the various steps have been measured. For the reaction at 30° C, it was found that the rate coefficient for the termination of two unlike radicals ( k tab = 2.06 x 10 8 ) was much greater than those for the termination of two styrene radicals ( k taa = 8 x 10 8 ) or of two methyl methacrylate radicals ( k tbb = 2.7 x 10 7 ). Finally, some data are presented on the osmotic behaviour of copolymers of styrene and methyl methacrylate in benzene solution.

Two-dimensional NMR studies of acrylate copolymers

2009 ◽  
Vol 81 (3) ◽  
pp. 389-415 ◽  
Author(s):  
A. S. Brar ◽  
Ashok Kumar Goyal ◽  
Sunita Hooda
Keyword(s):  
Methyl Methacrylate ◽  
Methyl Acrylate ◽  
Quantum Coherence ◽  
Multiple Bond ◽  
Microstructural Analysis ◽  
2D Nmr ◽  
Correlation Spectroscopy ◽  
Nmr Studies ◽  
Poly Methyl Methacrylate ◽  
Nmr Study

High-resolution NMR spectroscopy is the most versatile, reliable, and generally acceptable technique for the determination of the microstructure of polymers. 2D NMR techniques, along with 1D NMR, have more potential to study absolute configurational assignments and sequence distribution of copolymers. Physical and chemical properties of polymers are influenced fundamentally by their microstructure. We discuss the detailed microstructure analysis of a large number of homopolymers, copolymers, and terpolymers. 2D NMR study of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), and poly(methacrylonitrile) (PMAN) is discussed in this article. In addition to homopolymers, 2D heteronuclear single-quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple-bond correlation (HMBC) study of different copolymers such as poly(methyl methacrylate-co-methyl acrylate), poly(styrene-co-methyl methacrylate), and poly(methyl methacrylate-co-methacrylonitrile) have also been reported here. This in turn helps in microstructural analysis of terpolymers such as poly(methacrylonitrile-co-styrene-co-methyl methacrylate), poly(acrylonitrile-co-methyl methacrylate-co-methyl acrylate), and poly(ethylene-co-vinyl acetate-co-carbon monoxide).

Chain-Length-Dependent Termination in Acrylate Radical Polymerization Studied via Pulsed-Laser-Initiated RAFT Polymerization

2007 ◽  
Vol 60 (10) ◽  
pp. 779 ◽  
Author(s):  
Michael Buback ◽  
Pascal Hesse ◽  
Thomas Junkers ◽  
Thomas Theis ◽  
Philipp Vana
Keyword(s):  
Radical Polymerization ◽  
Chain Length ◽  
Near Infrared ◽  
Pulsed Laser ◽  
Monomer Concentration ◽  
Nir Spectroscopy ◽  
Single Pulse ◽  
Rate Coefficients ◽  
Radical Chain ◽  
Chain Flexibility

The chain-length dependence of the termination rate coefficient, kt, in methyl acrylate (MA) and dodecyl acrylate (DA) radical polymerization has been determined via the single pulse pulsed-laser polymerization near-infrared reversible addition–fragmentation chain transfer (SP-PLP-NIR-RAFT) technique. Polymerization is induced by a laser SP and the resulting decay in monomer concentration, cM, is monitored via NIR spectroscopy with a time resolution of microseconds. A RAFT agent ensures the correlation of radical chain length and monomer-to-polymer conversion. The obtained rate coefficients for termination of two radicals of approximately the same chain length, i, are represented by power-law expressions, kt(i,i) ∝ i–α. For both monomers, composite model behaviour of kt(i,i) showing two distinct chain length regimes is observed. The exponent αs referring to short chain lengths is close to unity, whereas the exponent αl, which characterizes the chain-length dependency of large radicals, is slightly above the theoretical value for coiled chain-end radicals. The crossover chain length, ic, which separates the two regions, decreases from MA (ic = 30) to DA (ic = 20). The results for MA and DA are consistent with earlier data reported for butyl acrylate. There appears to be a correlation of αs and ic with chain flexibility.

Sign in / Sign up

Export Citation Format

Share Document