Macropropagation Rate Coefficients and Branching Levels in Cationic Ring-Opening Polymerization of 2-Ethyl-2-oxazoline through Prediction of Size Exclusion Chromatography Data

Arráez, Francisco J.; Xu, Xiaowen; Steenberge, Paul H. M. Van; Jerca, Valentin Victor; Hoogenboom, Richard; D’hooge, Dagmar

doi:10.1021/acs.macromol.9b00544

Cited by 17 publications

(46 citation statements)

References 57 publications

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“…The matrix-based k MC algorithm to follow SI-RDRP kinetics on and near the surface is based on previous work [ 61 , 62 , 63 , 64 , 65 , 66 ] for the design of living and RDRP processes, starting from the stochastic rules pioneered by Gillespie [ 67 ]. Reaction events and the time at which these events occur are randomly selected according to the reaction probabilities calculated from so-called MC reaction rates expressed in s −1 :

in which

stands for the total MC reaction rate, which is calculated from the sum of the individual Monte Carlo reaction rates following from the so-called MC reaction channels (

).…”

Section: Kinetic Modeling Methodologymentioning

confidence: 99%

The Competition of Termination and Shielding to Evaluate the Success of Surface-Initiated Reversible Deactivation Radical Polymerization

2020

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One of the challenges for brush synthesis for advanced bioinspired applications using surface-initiated reversible deactivation radical polymerization (SI-RDRP) is the understanding of the relevance of confinement on the reaction probabilities and specifically the role of termination reactions. The present work puts forward a new matrix-based kinetic Monte Carlo platform with an implicit reaction scheme capable of evaluating the growth pattern of individual free and tethered chains in three-dimensional format during SI-RDRP. For illustration purposes, emphasis is on normal SI-atom transfer radical polymerization, introducing concepts such as the apparent livingness and the molecular height distribution (MHD). The former is determined based on the combination of the disturbing impact of termination (related to conventional livingness) and shielding of deactivated species (additional correction due to hindrance), and the latter allows structure-property relationships to be identified, starting at the molecular level in view of future brush characterization. It is shown that under well-defined SI-RDRP conditions the contribution of (shorter) hindered dormant chains is relevant and more pronounced for higher average initiator coverages, despite the fraction of dead chains being less. A dominance of surface-solution termination is also put forward, considering two extreme diffusion modes, i.e., translational and segmental. With the translational mode termination is largely suppressed and the living limit is mimicked, whereas with the segmental mode termination occurs more and the termination front moves upward alongside the polymer layer growth. In any case, bimodalities are established for the tethered chains both on the level of the chain length distribution and the MHD.

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in which

stands for the total MC reaction rate, which is calculated from the sum of the individual Monte Carlo reaction rates following from the so-called MC reaction channels (

).…”

Section: Kinetic Modeling Methodologymentioning

confidence: 99%

The Competition of Termination and Shielding to Evaluate the Success of Surface-Initiated Reversible Deactivation Radical Polymerization

2020

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“…For such corrections, a combination of experimental and theoretical analysis is worthwhile, as illustrated in Figure , considering CROP of 2‐ethyl oxazoline and the model parameters as reported in Arraez et al. [ 131 ]…”

Section: Resultsmentioning

confidence: 99%

“…This introduces complications for the SEC analysis, implying the need of special corrections at least for the branched population. For such corrections, a combination of experimental and theoretical analysis is worthwhile, as illustrated in Figure 8, considering CROP of 2-ethyl oxazoline and the model parameters as reported in Arraez et al [131] In such CROP (chain) initiation and propagation take place but also chain transfer to monomer through β-elimination, which is associated with macromonomer formation, as shown in Figure 8a. Upon monomer depletion, these macromonomers are incorporated forming mid-chain cations that upon propagation form LCBs.…”

Section: Bimodality In Crop Of 2-ethyl-oxazoline With Long-chain Branchingmentioning

confidence: 99%

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Translating Simulated Chain Length and Molar Mass Distributions in Chain‐Growth Polymerization for Experimental Comparison and Mechanistic Insight

Marien

Edeleva

Figueira

et al. 2021

Macro Theory & Simulations

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From an industrial point of view, it has often been claimed that MMDs need to possess a sufficiently large mass average molar mass M m (e.g., 10 6 g mol −1 ) to ensure sufficient entanglements and must be broad, requiring dispersity (Ð) values well above 1.5. [5,8] For specific applications, such as coatings, MMD bimodality has even been put forward as the primary target, leading to dispersity values higher than 4. [15][16][17] For the determination of the radical propagation, [18][19][20][21][22][23] backbiting, [24][25][26][27] and β-scission [24,28] rate coefficients or the quantification of photo dissociation quantum yields, [29] a modulated MMD trace is beneficial. In contrast to modulated and broad MMDs, the more recent chemical development of living and reversible deactivation radical poly merization (L/RDRP) mechanisms has made clear that more niche applications (e.g., drug delivery or high-end cosmetics) can benefit from lower M m values (e.g., 10 4 g mol −1 ) and narrow monomodal MMDs with Ð values below 1.5. [30][31][32][33][34][35][36] This dedicated molecular tailoring is also related to control over end-group functionality to enable the synthesis of more special polymers such as block, gradient, and star (co)polymers. [37][38][39][40][41] Therefore, a dedicated knowledge of the relationship between reaction conditions and MMD is indispensable for any polymerization mechanism.The key analytical tool for MMD characterization is size exclusion chromatography (SEC) or equivalently gel permeation chromatography (GPC) in which longer chains-so species with higher molar masses-elute first, as they have fewer interactions with the smaller pores in the packed columns. The chains with the highest molar masses are thus located at the lowest retention times (RTs) in the chromatogram so that the recorded chromatogram corresponds to a "reverse" MMD. This is illustrated in Figure 1a employing a refractive index (RI) detector, which is also known as single GPC detection. Ideally, calibration takes place with standards of the same polymer type that are characterized by very narrow MMDs (Ð values close to 1), as demonstrated in Figure 1b. In many research groups, one finally aims at a log-MMD representation, requiring a normalization on logarithmic scale. This is illustrated by the arrow between Figure 1c,d and leadsThe molar mass distribution (MMD), which is also known as the molecular weight distribution (MWD), is a key molecular property for a polymerization process, as it determines polymer strength and polymeric material deformation. Several MMD and related chain length distribution (CLD) representations are however used interchangeably, often leading to biased conclusions. Herein it is highlighted how the most interesting simulated CLD/MMD representations, i.e., the number, mass, z-based, and logarithmic CLD/MMD, can be translated into each other and how they need to be corrected to facilitate comparison with experimental size exclusion chromatography traces. Their relevance is highlighted by including case st...

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“…23,35 This results in the formation of branched species upon further propagation of the mid-chain cation species (first-rate coefficient k pMid and afterward k p ). 30,38 For multifunctional systems, macropropagation also serves as the main reaction pathway through which star-star coupling can take place.…”

Section: Papermentioning

confidence: 99%

Differences and similarities between mono-, bi- or tetrafunctional initiated cationic ring-opening polymerization of 2-oxazolines

Arráez

Edeleva

et al. 2022

Polym. Chem.

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Macropropagation Rate Coefficients and Branching Levels in Cationic Ring-Opening Polymerization of 2-Ethyl-2-oxazoline through Prediction of Size Exclusion Chromatography Data

Cited by 17 publications

References 57 publications

The Competition of Termination and Shielding to Evaluate the Success of Surface-Initiated Reversible Deactivation Radical Polymerization

The Competition of Termination and Shielding to Evaluate the Success of Surface-Initiated Reversible Deactivation Radical Polymerization

Translating Simulated Chain Length and Molar Mass Distributions in Chain‐Growth Polymerization for Experimental Comparison and Mechanistic Insight

Differences and similarities between mono-, bi- or tetrafunctional initiated cationic ring-opening polymerization of 2-oxazolines

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