Advanced Monte Carlo Model for Arborescent Polyisobutylene Production in Batch Reactor Yutian R. Zhao, Kimberley B. McAuley,* Piet D. Iedema, Judit E. Puskas An advanced Monte Carlo (MC) model is developed to predict the molecular weight distribution and branching level for arborescent polyisobutylene produced in a batch reactor via carbocationic copolymerization of isobutylene and an inimer. This new MC model uses differential equations and ran- dom numbers to determine the detailed structure of dendritic polymer molecules. Results agree with those from a traditional MC model for the same system, but the proposed model requires considerably less computational effort. The proposed MC model is also used to obtain information about polymer segments be- tween branch points and dan- gling polymer segments. CH 2 C H 3 C H 3 CH 3 CH 3 CH 3 CH 3 C H 3 C H 3 CH 3 CH 3 CH 3 C H 3 C H 3 C H 3 C H 3 C H 3 CH 3 C H 3 CH 3 CH 3 CH 3 C H 3 CH 3 CH 3 Cl C H 3 CH 3 Cl CH 3 CH 3 CH 3 CH 3 Cl CH 3 CH 3 C H 3 CH 3 Cl CH 3 C H 3 Cl CH 3 C H 3 1. Introduction Because of their unique chemical and physical properties, synthesis of arborescent polymers has been studied by many researchers. [1–5] The discovery of self-condensing vinyl polymerization (SCVP) by Fr echet et al. [6] greatly simplified the process of synthesizing arborescent poly- mers. SCVP uses inimers (i.e., molecules that act both as initiator and monomer) to create the arborescent structure. Figure 1 shows a typical inimer (IM) molecule, which has a vinyl group that can polymerize and a chloride group that can be removed to initiate carbocationic polymerization. By copolymerizing this IM with isobutylene (IB), Puskas et al. [7–11] developed a simple method to produce poly- isobutylene (PIB) with an arborescent or tree-like structure and used this new material as a core to produce block copolymers with polystyrene end blocks. This block copolymer has excellent mechanical properties, biocom- patibility, and biostability, making it a very promising material for human implantation, [7,12–17] especially for breast implants. [18] Figure 2 shows a simplified reaction mechanism of ‘‘one- pot’’ living copolymerization of IM and IB developed by Puskas et al. [7–11,19–22] The first step is an exchange reaction that converts 4-(2-methoxyisopropyl)styrene (MeOIM) to IM. A large excess of TiCl 4 , which is a Lewis acid (LA), is often used in the experiments to ensure that this exchange reaction goes to completion and that there is sufficient LA to initiate the living carbocationic polymerization. A proton trap (e.g., 2,6-di-tert-butylpyridine) is used in the polymeri- zation to remove other sources of initiation (e.g., proton initiation due to trace amounts of water). [19] The second step is a reaction between IM and IB molecules to form arborescent polymer molecules. Step two involves two different types of vinyl groups (V I from IM and V M from IB) Prof. K. B. McAuley, Y. R. Zhao Department of Chemical Engineering, Queen’s University, Kingston, ON, Canada K7L 3N6 E-mail: kim.mcauley@chee.queensu.ca Prof. P. D. Iedema Department of Chemical Engineering, University of Amsterdam, 1018 WV, Amsterdam, The Netherlands Prof. J. E. Puskas Department of Chemical Engineering, University of Akron, Akron, OH USA 44325 Full Paper ß 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Macromol. Theory Simul. 2014, DOI: 10.1002/mats.201400013 1 wileyonlinelibrary.com Early View Publication; these are NOT the final page numbers, use DOI for citation !! R