A replicated investigation of nitroxide‐mediated radical polymerization of styrene over a range of reaction conditions

Abstract

A comprehensive experimental investigation of nitroxide-mediated radical polymerization (NMRP) of styrene using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as controller is presented. Polymerizations with a bimolecular initiator (benzoyl peroxide; BPO) were carried out at 120 and 130 • C, with TEMPO/BPO molar ratios ranging from 0.9 to 1.5. Results indicate that increasing temperature increases the rate of polymerization while the decrease in molecular weights is only slight. It was also observed that increasing the ratio of TEMPO/BPO decreased both the rate of polymerization and molecular weights. Probably for the first time in the history of such investigations, the paper contains a comprehensive database, appropriate for parameter estimation in aid of future modelling studies, since it comes from a systematic data collection containing independent replication.On présente uneétude expérimentale approfondie de la polymérisation radicalaire basée sur les nitroxydes (NMRP) du styrèneà l'aide de tétraméthyl-2,2,6,6 pipéridinyloxy-1 (TEMPO) comme agent de contrôle. Des polymérisationsà l'aide d'un initiateur bimoléculaire (peroxyde de benzoyle, BPO) ontété menéesà 120 et 130 • C, avec des rapports molaires de TEMPO/BPO variant entre 0,9à 1,5. Les résultats indiquent que l'augmentation de température accroît la vitesse de polymérisation tandis que la baisse des masses moléculaires n'est que légère. On aégalement observé que l'augmentation du rapport de TEMPO/BPO diminueà la fois la vitesse de polymérisation et les masses moléculaires. Probablement pour la première fois dans l'histoire de ce type de recherches, l'article contient une base de données complète, convenantà l'estimation de paramètres en vue d'études de modélisation futures,étant issue d'une collecte de données systématique.

Effect of initiator type and concentration on polymerization rate and molecular weight in the bimolecular nitroxide‐mediated radical polymerization of styrene

“…4b). Nabifar et al 20 reported similar results for the living free radical polymerization of styrene using BPO as the initiator and considering tempera- tures of 120 and 130…”

“…2b that the profiles considering different molar ratios of TEMPO and TBEC are very similar. Nabifar et al 20 also related that the effect of this factor on molecular weights was not pronounced for some experimental conditions. Figure 2b also shows that the molecular weights increase linearly with conversion, which is expected for a controlled polymerization process.…”

“…After this period, the polymerization rate follows standard NMRP kinetics. More data on NMRP using BPO as initiator can be found in Nabifar et al, 20 who studied the effect of temperature and molar ratio between TEMPO and BPO on polymerization rate, molecular weight, and polydispersity and in Roa-Luna et al, 21 who studied diffusion effects in NMRP of styrene in the presence of TEMPO and BPO. On the other hand, TBEC has a relatively low decomposition rate at this temperature (k d = 0.017 min −1 ).…”

Diagnostic Checks and Measures of Information in the Bayesian Design of Experiments with Complex Polymerizations

“…We are not offering a literature (or background) review on NMRP, as the emphasis here is to demonstrate the benefits of specific aspects of the Bayesian design of experiments and not the kinetics of NMRP. For the interested reader, kinetic and modeling information closely related to the case study presented herein could be found in references [5][6][7]. The case study that follows implements the Bayesian design steps of Table 3, with added emphasis on the interpretation of diagnostic criteria and information measures.…”

A Sequential Iterative Scheme for Design of Experiments in Complex Polymerizations

“…Molecular weight is selected to be measured at 50 % conversion, first of all because 50 % is the mid-point of the process, so the molecular weight behavior is well established by then. In addition, prior experimental information [13,14] advises that molecular weight measurements show more scatter at higher conversion levels (80-95 %) for NMRP of styrene. Replicates of molecular weight measurements available from prior experimental work can give a good idea about the expected variability in the response.…”