Gelation in Living Copolymerization of Monomer and Divinyl Cross-Linker: Comparison of ATRP Experiments with Monte Carlo Simulations

Abstract

Two types of Monte Carlo simulations were carried out to simulate gelation in a living copolymerization of monovinyl monomer and divinyl cross-linker. The simulated gel points under various conditions were compared to the experimental gel points obtained in series of ATRP reactions and the calculated gel points based on Flory−Stockmayer (FS) theory. The first simulation was based on an off-lattice (OL) model, simplified by ignoring the geometry of macromolecules. The second more complex simulation was based on the dynamic lattice liquid (DLL) model. Both OL model and FS mean-field theory were capable to count on the influence of molar ratios of cross-linker to initiator and initiation rate on the gel points. However, the simulated gel points occurred at much lower monomer conversion, as compared to the experimental results. Furthermore, the solvent dilution, an important parameter to adjust the experimental gel points, had no effect on the gel points in both OL simulation and FS theory. In contrast, the DLL simulation based on a cooperative motion of elements on a lattice successfully predicted the effect of solvent dilution on the gel points. Addition of solvent beads in the DLL system decreased the concentrations of initiator, cross-linker, and monomer and significantly postponed the gel points. A decreasing targeted DP of primary chains, while keeping the molar concentrations of initiator and cross-linker constant, also resulted in a delayed gelation, which was confirmed by the ATRP experiments under similar conditions. These results provide means to understand the dependence of gel points on various parameters and can serve as a basis for the development of more advanced simulation models of the controlled/living copolymerization systems.

Synthesis of nanogels/microgels by conventional and controlled radical crosslinking copolymerization

“…They provide indeed a useful tool to understand the influence of various experimental parameters (such as dilution, monomer/control agent ratio and crosslinker concentration) on the onset of gelation. 79 CRP techniques have thus successfully been applied to the controlled synthesis of nano-/microgels, i.e. networks which are limited in size and molar mass.…”

Modeling of the Production of Hydrogels from Hydroxyethyl Methacrylate and (Di)Ethylene Glycol Dimethacrylate in the Presence of RAFT Agents

“…The moment equations which result under the midpoint approximation and allow calculation of average properties are shown in Equation (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). [13] The V coefficients of Equation (8) are transformed into Z coefficients upon application of the method of moments (not shown here since they do not appear as such in the final moment equations) and are contained within the explicit terms of Equation (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) under the midpoint approximation. Equation (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) already contains the closure expressions needed to evaluate the second order moments (see refs.…”

“…[1][2][3][4][5][6][7] Modeling of the copolymerization kinetics of vinyl/ divinyl monomers in the presence of RAFT controllers has started to be addressed in the literature. [8][9][10][11][12][13] Other models for copolymerization of vinyl/vinyl monomers in the presence of INIFERTER, [14] ATRP [15][16][17][18][19][20][21][22][23][24] and NMRP [7,21,23,[25][26][27][28] controllers have also been published. In this contribution, we use the model developed by Hern andez-Ortiz et al, [13] who illustrated it for the bulk/solution RAFT copolymerization of styrene/divinylbenzene, for the bulk/solution copolymerization of hydroxyethyl methacrylate (HEMA)/ ethylene glycol dimethacrylate (EGDMA) and HEMA/ diethylene glycol dimethacrylate (DEGDMA), and also use it as a first approximation for the RAFT dispersion copolymerization of HEMA/EGDMA in supercritical carbon dioxide (scCO 2 ).…”

Kinetic Modeling of Hyperbranched Polymer Synthesis through Atom‐Transfer and Nitroxide‐Mediated Radical Polymerization of Vinyl/Divinyl Monomers

“…(4)- (9). The key information to be used in this kind of interpretation of polymerization systems is the description of the kinetic scheme involved (including all rate coefficients requirements) as well as the operating conditions (batch/semi-batch, CSTR, and their associations).…”