Design Criteria for Accurate Measurement of Bimolecular Radical Termination Rate Coefficients via the RAFT‐CLD‐T Method

Abstract

The reversible addition‐fragmentation chain transfer chain length dependent termination (RAFT‐CLD‐T) technique allows a simple experimental approach to obtain chain‐length‐dependent termination rate coefficients as a function of conversion, k titalici,i(x). This work provides a set of criteria by which accurate k titalici,i(x) can be obtained using the RAFT‐CLD‐T method. Visualization of three‐dimensional plots varying all kinetic rate parameters and starting concentrations demonstrates that only certain combinations give an accurate extraction of k titalici,i(x). The current study provides hands‐on guidelines for experimentalists applying the RAFT‐CLD‐T method.

Living Radical Polymerization by the RAFT Process - A Second Update

“…[19] Criteria for selecting conditions for the determination of termination rate constants by the RAFT-CLD-T method have been proposed and justified by kinetic simulation. [430] The RAFT-CLD-T method has been used to determine chain length dependent termination rate constants in MMA polymerization in various conversion regimes up to high conversion [119,120] and termination rate constants during formation of star polymers based on MMA, MA, and St. [20,256] In the SP-PLP-NIR-RAFT method, polymerization is induced by a single laser pulse (SP) and the resulting decay in monomer concentration, c M , is monitored by NIR spectroscopy with a time resolution of microseconds. The presence of a RAFT agent ensures the correlation of radical chain length and monomer-to-polymer conversion.…”

Full Molecular Weight Distribution in RAFT Polymerization. New Mechanistic Insight by Direct Integration of the Equations

“…Previous works have modeled the FMWD of some of these populations using different techniques. Many of them have used the commercial package Predici,9, 10, 19–23 which is based on a weighted residual method directly applied over the discrete chain‐length variable (Galekin h – p );24–27 nonetheless, although this software can essentially represent the RAFT mechanism in a correct way, it is unfortunately not able to provide the FMWD of the intermediate radical population, which can be a key piece for the elucidation of the mechanisms. The algorithms implemented in Predici essentially solve only 1‐D chain populations, therefore the simulation of the RAFT chemistry in Predici has used two separate species in order to represent the two arms of the intermediate radical population a9, 10, 27.…”

Exploiting (Multicomponent) Semibatch and Jacket Temperature Procedures to Safely Tune Molecular Properties for Solution Free Radical Polymerization of n‐Butyl Acrylate

“…On the microscale, i.e., the scale at which concentrations can be defined, [ 55 ] diffusional limitations on termination are taken into account according to so‐called composite k t ‐model delivering apparent termination rate coefficients, considering literature parameters to account for polymer mass fraction and chain length dependencies (see Section S1 of the Supporting Information). [ 3,56–60 ] This composite termination model must be implemented in the actual k MC algorithm to properly reflect the apparent termination kinetics. In particular, the choice of the calculation method for the average apparent termination rate coefficient < k t,app > is crucial, as well as how frequently < k t,app > is updated.…”