Detailed investigation of the propagation rate of urethane acrylates

Abstract

Propagation rate coefficients are provided—for the first time—for an entire class of urethane moieties containing acrylates, which display an extremely high propagation rate.

Design concepts for diffusive holographic photopolymers

“…In the latter case, many initial parameter values for the iterative fit procedure are drawn from the results of independent experiments. These include not only the component refractive indices, but also the polymerization rate coefficient k p (from pulsed‐laser polymerization in combination with size‐exclusion chromatography) and the conversion‐induced slowing coefficient α (from shear modulus measurements). Finally, the set of parameters obtained from an iterative fit is further validated against experimental results at different grating pitches.…”

Determining Free‐Radical Propagation Rate Coefficients with High‐Frequency Lasers: Current Status and Future Perspectives

“…Poly(acrylonitrile) displays a poor solubility in its own monomer solution and propylene carbonate (PC) was found to be the solvent of choice due to the good solubility of the polymer, the low melting point, and its stability towards laser irradiation at 351 nm . For the urethane acrylates (2‐(phenylcarbamoyloxy)ethyl acrylate (PhCEA), 2‐(hexylcarbamoyloxy)ethyl acrylate (HCEA), 2‐(phenylcarbamoyloxy) iso ‐propyl acrylate (PhCPA), 2‐(hexylcarbamoyloxy) iso ‐propyl acrylate (HCPA), and hydroxypropylcarbamate acrylate (HPCA)) the crystallinity of the monomer and their relatively high melting point of close to 70 °C (depending on the monomer) required the use of a solvent to allow proper PLP–SEC experiments . Employing high‐frequency laser systems, propagation rate coefficients ranging from k p 50 °C = 5800 L mol −1 s −1 for acrylonitrile up to k p 50 °C = 58 600 L mol −1 s −1 for the to‐date fastest investigated monomer 2‐(phenylcarbamoyloxy)ethyl acrylate, PhCEA—spanning one order of magnitude—have been successfully determined for temperatures of up to 80 °C.…”

“…However, an interesting observation is made when comparing HCPA with PhCPA, where the hexyl‐substituted species shows a higher propagation rate coefficient than the phenyl substituted one, in contrast to the expected behavior. This might be explained by the fact that introducing an iso ‐propyl group has a larger effect on the sterics of the reaction and the transition state than exchanging the phenyl ring for a hexyl group . For linear alkyl acrylates, a possible effect on the propagation rate coefficient while exchanging the side chains can lead back to dipolar interactions.…”

The Effect of Hydrogen Bonding on Intramolecular Chain Transfer in Polymerization of Acrylates

“…[33,34] Application of a 500 Hz laser extends the temperature range over which chain-end propagation may be measured using the PLP-SEC technique; [9] however, the loss of PLP structure in the polymer MMDs at 70-80 8C is still attributed to the effect of backbiting not only for BA, [9] but also for isobornyl acrylate, tert-butyl acrylate and 1-ethoxyethyl acrylate, [35] and a series of carbamate acrylates. [36] While the above survey is far from exhaustive, it indicates that the intramolecular chain-transfer reaction is a general feature of acrylate monomers, regardless of the size or functionality of the ester group. Thus, we were very surprised to find that this mechanism is greatly suppressed (or even completely eliminated) for the polymerization of 2-hydroxyethyl acrylate (HEA), a functional monomer whose copolymers have variety of commercial applications as adhesives, biomaterials, and coatings.…”