Progress in Computer Simulation of Bulk, Confined, and Surface‐initiated Polymerizations

Bain, Erich D.; Turgman‐Cohen, Salomon; Genzer, Jan

doi:10.1002/mats.201200030

Cited by 25 publications

(27 citation statements)

References 182 publications

(221 reference statements)

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“…In addition, the determination of σ chains is usually more onerous than measuring the (average) molar mass [ 14 , 42 ], therefore making it more difficult to access detailed experimental information on the conformations of the surface-tethered polymer chains. In contrast, experimental analysis of the chains in solution is relatively straightforward but not recommended [ 15 , 42 , 43 , 44 ], as the kinetics for chain formation in the solution and on the surface are completely different, due to a very strong impact of confinement effects exerted by the presence of the surface. For example, the likelihood that two active chains at the surface can terminate with each other is much lower than if those two chains are free in the solution, as conceptually illustrated in Figure 2 (bottom).…”

Section: Introductionmentioning

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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Section: Introductionmentioning

confidence: 99%

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

2020

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“…Therefore, statistical arguments are used in Section for the “equireactive” case (all reaction rates are identical) to derive analytical expressions for the number and weight average molar mass of the reaction products. The Monte‐Carlo simulations allow to compute the molar mass distribution of the full sample and specific weight distributions of particular moieties can be analyzed. We use these to derive moiety specific degrees of polymerization as molecules with or without a particular type of moiety may be separated out of the reaction bath or may dominate the molar mass as in ref.…”

Section: Introductionmentioning

confidence: 99%

Competing Exchange and Irreversible Reactions in a Linear Co‐Polycondensation Lead to a Broad Composition Window Where Tunable High Molecular Weight Polymers can be Prepared

Lang

Böhme

2019

Macro Theory & Simulations

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A co‐polycondensation reaction is discussed analytically and by Monte‐Carlo simulations where two reactive units compete for reactions with an alternating third reactive unit, whereby irreversible reactions replace bonds which are able to undergo exchange reactions. The resulting number average molar mass, Mn, exhibits only one distinct peak at the stoichiometric condition of both competitors with the alternating partner. The weight average molar mass, Mw, reaches an additional second peak at the stoichiometric condition between the dominating competitor and the alternating partner. Both peaks of Mw surround a range of compositions where a rather high and approximately constant Mw is obtained. The degree of polymerization of the dominating and alternating reaction partners is rather insensitive towards composition fluctuations if the reaction mixture remains within this composition window. This promotes high molecular weight species and more homogeneous weight distributions at incomplete mixing conditions. An ideal reference case (identical reaction rates for all reactions) is solved analytically to describe these reactions. The position of the stable composition window and the average molar masses inside this window can be tuned by choosing appropriate precursor molecules, reaction mixtures, or post‐tuning steps at later times.

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“…The conformation of the polymer brush is mainly governed by the interplay between Mn and the grafting density (σ p ) . σ p is difficult to determine directly; however, it can be calculated by using the known values of dry polymer thickness ( h p ) and M n :

σ_{p} = \frac{N_{A} ρ h_{p}}{M_{n}}

In Equation , N A is Avogadro's number and ρ is the bulk density of the polymer.…”

Section: Methodsmentioning

confidence: 99%

Chain End‐Functionalized Polymer Brushes with Switchable Fluorescence Response

Taş

Kopeć

Pol

et al. 2019

Macro Chemistry & Physics

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Herein is described the switchable fluorescence response of poly(methyl methacrylate) (PMMA) brushes. Chain end fluorescein labeled PMMA brushes are prepared by combining surface‐initiated atom transfer radical polymerization (SI‐ATRP) with a copper‐catalyzed alkyne‐azide cycloaddition (CuAAC) click reaction. Successful attachment of fluorescein is confirmed by measuring fluorescence of the as‐prepared films. Utilizing co‐solvency of PMMA in isopropanol‐water mixtures, responsive behavior of the end‐functionalized brushes is demonstrated by measuring the changes in fluorescence intensity between the swollen and collapsed states.

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Progress in Computer Simulation of Bulk, Confined, and Surface‐initiated Polymerizations

Cited by 25 publications

References 182 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

Competing Exchange and Irreversible Reactions in a Linear Co‐Polycondensation Lead to a Broad Composition Window Where Tunable High Molecular Weight Polymers can be Prepared

Chain End‐Functionalized Polymer Brushes with Switchable Fluorescence Response

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