Copolymerization of n‐Butyl Acrylate and Styrene: Terminal vs Penultimate Model

Abstract

The batch solution copolymerization of styrene and n-butyl acrylate over a range of styrene feed compositions is analyzed by in situ 1 H NMR to monitor individual and overall monomer conversions, as well as by 13 C NMR and size exclusion chromatography (SEC)/multi-angle light scattering (MALS) for the branching density and molecular weight, respectively. Both the terminal and penultimate models, using rate coeffi cients taken from the literature, fail to predict the full extent of the reduced overall copolymerization rate observed when the styrene composition in the feed is increased. After estimation of uncertain model parameters, the terminal model provides a good representation of the experimental dataset. The estimated overall effi ciency of the initiator decreases (from the typically employed 0.65 to 0.35) and the cross-termination increases from the values corresponding to the geometric mean of the homopolymerization termination rate coeffi cients.

Soft core–hard shell latex particles for mechanically strong VOC‐free polymer films

“…This observation is an effect of residual monomer present in the seed at the beginning of the second‐stage process. As the reactivity ratios of the monomer used favor the polymerization of styrene over butyl acrylate, residual monomer in the seed is predominantly composed of BA . As such, at the start of the second‐stage process, the monomer in the system is richer in BA.…”

Pseudo-Homopolymerization Approach To Predict the Molecular Weight Distribution in the Copolymerization via Activator Regenerated by Electron Transfer Atom Transfer Radical Polymerization

“…53 ≤ + × − K CL DP (DP DP ) n n max med 2 1/2 (49) where DP med = μ 2 /μ 1 , and μ 2 and μ 1 are the second and first total moments, respectively; K is a safety factor (times the standard deviation) to capture most of the information. Furthermore, in this work the following empirical approximation is used = + − CL DP 30(DP DP ) n w n max 1/2 (50) As initial condition, CL max = 100 to ascertain that all chain lengths are taken into account in the computation of the MWD.…”

“…Furthermore, semibatch reactor strategies have been studied in which an additional solution of reducing agent is fed in the system; if a low concentration solution is added to the reactor, the effect over the molecular structure properties (M n and Đ) is almost negligible. To delve deeper into this interesting behavior, we are expanding the investigation following what was initially explored by Payne et al 26 In the following simulations, a high concentration of reducing agent (0.1 M) is added after 10,20,30,40,50, and 60% of overall conversion assuming that the addition does not change the density of the reaction mixture. As expected, a strong increment in the polymerization rate is obtained after the supplementary charge of reducing agent occurs (Figure 8a); because a higher concentration of Cu I X/L complex is regenerated, the equilibrium ratio is therefore modified to produce more growing chains.…”

“…As Δt is increased to 0.4 s, the computation time is reduced to a short time of 3.38 s. The integration efficiency is improved due to the diminution of the dimension in the ODE system from 1800 equations of the original system to 600 equations of the Figure 8. Effect of the variation on the addition of reducing agent at different conversions (10,20,30,40,50, and 60%) in a semibatch system in ARGET ATRcoP with 70 wt % BA in the feed monomer composition. Evolution of (a) conversion on time, (b) M n , (c) dispersity on conversion, (d) chain length distribution, (e) EGF, and (f) initiator efficiency on conversion.…”

The influence of adding functionality to dispersant and particle core compositions in non-aqueous dispersion polymerization

“…It is also known that acrylate polymer MWs are reduced when ST is added to a homogeneous polymerization system due to the slower polymerization rate. [22] Both explanations, lowered propagation rates and chain transfer of the styrenic radicals to the macromer, can be applied to explain the lower M w seen for the MA/ST core. While an interesting kinetic question, the important finding is that the M w values of the NAD are not greatly affected by the addition of ST to the recipe, remaining greater than 55 000…”