The three-dimensional arrangement of natural and synthetic network materials determines their application range. Control over the real time incorporation of each building block and functional group is desired to regulate the macroscopic properties of the material from the molecular level onwards. Here we report an approach combining kinetic Monte Carlo and molecular dynamics simulations that chemically and physically predicts the interactions between building blocks in time and in space for the entire formation process of three-dimensional networks. This framework takes into account variations in inter-and intramolecular chemical reactivity, diffusivity, segmental compositions, branch/network point locations and defects. From the kinetic and three-dimensional structural information gathered, we construct structure-property relationships based on molecular descriptors such as pore size or dangling chain distribution and differentiate ideal from non-ideal structural elements. We validate such relationships by synthetizing organosilica, epoxy-amine and Diels-Alder networks with tailored properties and functions, further demonstrating the broad applicability of the platform.

We pioneer the synthesis of well-defined high molar mass segmented copolymers, employing a unique combination of step-growth and reversible addition–fragmentation chain transfer (RAFT) polymerization. The step-growth precursor polymer is obtained via the ambient temperature UV-light-induced Diels–Alder reaction of 6′-(propane-1,3-diylbis­(oxy))­bis­(2-methyl­benzaldehyde) (AA monomer) and di­(isopropionic ethyl ester fumarate) trithio­carbonate (BB monomer). Unconventional off-stoichiometric conditions (r = [AA]0:[BB]0 = 1.5–1.75) are employed to ensure a sufficiently high incorporation of BB in the step-growth product (1200 ≤ M n/g mol–1 ≤ 3950). The optimum r value is based on a detailed product distribution analysis, comparing experimental and bivariate kinetic Monte Carlo generated data, using a scheme of over 200 reactions. The analysis highlights the unexpected occurrence of AA homopolymerization and the ligation of the resulting AA segments at higher reaction times. The precursor step-growth polymer is successfully transformed into a segmented copolymer via insertion of styrene by RAFT polymerization at 60 °C (11 200 ≤ M n/g mol–1 ≤ 53 400), as confirmed both experimentally and through simulations.

A detailed kinetic study on the para-fluoro-thiol reaction (PFTR) using experimental analysis and kinetic Monte Carlo modeling is introduced, covering the difference in reactivity of a selected variety of structurally different thiols, uniquely including polymeric thiols.

By combining experimental and modeling tools, a detailed characterization study of MADIX properties becomes possible.

For the industrial expandable polystyrene (EPS) process, the Predici software package is successfully applied to demonstrate that the composite kt model is the most appropriate one to accurately account for diffusional limitations on termination. For a broad range of conditions, the reported set of model parameters allows an excellent description of experimental data on monomer conversion and molar mass distribution (MMD). For low temperatures and dicumylperoxide amounts (<403 K; < 0.20 m % DCP), a bimodal log‐MMD is obtained, which can be explained by the inability of chain transfer to attenuate the gel‐effect. For the opposite conditions, a unimodal log‐MMD results as the composite kt model provides an excellent description of the termination rates of the by chain transfer formed radicals. A unimodal log‐MMD also follows by adding a sufficiently high amount of the blowing agent n‐pentane (∼20 m %). The impact of degradation reactions on the EPS product can be neglected. © 2016 American Institute of Chemical Engineers AIChE J, 63: 2043–2059, 2017

Herein, we introduce an additive-free visible-lightinduced Passerini multicomponent polymerization (MCP) for the generation of high molar mass chains.Inplace of classical aldehydes (or ketones), highly reactive,insitu photogenerated thioaldehydes are exploited along with isocyanides and carboxylic acids.P rone to side reactions,t he thioaldehyde moieties create ac omplex reaction environment which can be tamed by optimizing the synthetic conditions utilizing stochastic reaction path analysis,h ighlighting the potential of semibatch procedures.O nce the complex MCP environment is understood, step-growth polymers can be synthesized under mild reaction conditions which-after aM umm rearrangement-result in the incorporation of thioester moieties directly into the polymer backbone,leading to soft matter materials that can be degraded by straightforwarda minolysis or chain expanded by thiirane insertion.

Bulk and solution radical polymerization is important in daily live. A challenge is still to maximize polymerization rate and control over molecular characteristics such as the molar mass distribution. The last decades have made clear that kinetic modeling is indispensable with originally most focus on deterministic implementations such as the method of moments (MoM) and only more recently promising results for event‐driven kinetic Monte Carlo (kMC) simulations that belong to stochastic methods. Computationally, a critical reaction is termination for which one has both distinguishable and nondistinguishable distributed species, which requires a delicate treatment of a stoichiometric factor 2. Proper benchmarking of MoM and kMC simulations demands thus a careful translation of this factor in the Monte Carlo (MC) reaction probabilities. However, limited attention has been paid in the kMC field to the detailed description of such translations. Here, a rigorous derivation is presented on the level of individual termination rates. Emphasis is on termination by recombination and disproportionation. It is highlighted that six types of factor 2 exist that all need to be incorporated with care, including an IUPAC‐based one. The consistency is demonstrated by a successful benchmark of essential modeling results for free radical polymerization of methyl methacrylate.

A challenge in the field of polymer network synthesis by a step-growth mechanism is the quantification of the relative importance of inter- vs. intramolecular reactions. Here we use a matrix-based kinetic Monte Carlo (kMC) framework to demonstrate that the variation of the chain length distribution and its averages (e.g., number average chain length xn), are largely affected by intramolecular reactions, as mostly ignored in theoretical studies. We showcase that a conventional approach based on equations derived by Carothers, Flory and Stockmayer, assuming constant reactivities and ignoring intramolecular reactions, is very approximate, and the use of asymptotic limits is biased. Intramolecular reactions stretch the functional group (FG) conversion range and reduce the average chain lengths. In the likely case of restricted mobilities due to diffusional limitations because of a viscosity increase during polymerization, a complex xn profile with possible plateau formation may arise. The joint consideration of stoichiometric and non-stoichiometric conditions allows the validation of hypotheses for both the intrinsic and apparent reactivities of inter- and intramolecular reactions. The kMC framework is also utilized for reverse engineering purposes, aiming at the identification of advanced (pseudo-)analytical equations, dimensionless numbers and mechanistic insights. We highlight that assuming average molecules by equally distributing A and B FGs is unsuited, and the number of AB intramolecular combinations is affected by the number of monomer units in the molecules, specifically at high FG conversions. In the absence of mobility constraints, dimensionless numbers can be considered to map the time variation of the fraction of intramolecular reactions, but still, a complex solution results, making a kMC approach overall most elegant.