Universal Relationships in Hyperbranched Polymer Architecture for Batch and Continuous Step Growth Polymerization of AB2-Type Monomers

Abstract

Design and control of hyperbranched (HB) polymer architecture by way of reactor operation is key to a successful production of higher-valued HB polymers, and it is essential in order to clarify the fundamental structural characteristics formed in representative types of reactors. In this article, the irreversible step growth polymerization of AB2 type monomer is investigated by a Monte Carlo simulation method, and the calculation was conducted for a batch and a continuous stirred-tank reactor (CSTR). In a CSTR, a highly branched core region consisting of units with large residence times is formed to give much more compact architecture, compared to batch polymerization. The universal relationships, unchanged by the conversion levels and/or the reactivity ratio, are found for the mean-square radius of gyration Rg2, and the maximum span length LMS. For batch polymerization, the g-ratio of Rg2 of the HB molecule to that for a linear molecule conforms to that for the random branched polymers represented by the Zimm-Stockmayer equation. A single linear equation represents the relationship between Rg2 and LMS, both for batch and CSTR. Appropriate process control in combination with the chemical control of the reactivity of the second B-group promises to produce tailor-made HB polymer architecture.

Random Branching of Polymer Chains with Schulz–Zimm Distribution. 2. Radius of Gyration and Maximum Span Length

“…For linear chains, L MS is directly equal to the chain length. It is expected that the magnitude of L MS has a significant effect on Rg 2 , and in this article, a linear relationship between Rg 2 and L MS will be reported, as already found for the hyperbranched polymers11,12 and for the long‐chain branched polymers with a heterogenous distribution of branch points 6…”

“…For perfect dendron polymers, the following linear relationship was found11,12 …”

“…Incidentally, the step‐growth polymerization of AB 2 ‐type monomer in a batch reactor leads to form the random branched architecture whose primary chains conform to the most probable distribution,19 and therefore, the agreement of a ≈ 0.18 for this particular hyperbranched architecture is reasonable. Interestingly, a ≈ 0.18 holds true also for the hyperbranched polymers formed in a continuous stirred‐tank reactor (CSTR), for which formed branched architecture is much more compact compared with that formed in a batch reactor 11,12…”

“…In addition to Rg 2 , the maximum span length L MS , which is the longest end‐to‐end path length represented by the number of monomeric units, is considered 6,9–12. For linear chains, L MS is directly equal to the chain length.…”

Universal Relationships in Branched Architecture Formed in Conventional and Living Emulsion Polymerization

“…For the hyperbranched polymer molecules formed through the self‐condensing vinyl polymerization, as well as the step polymerization of AB 2 ‐type monomer, the coefficient of 0.18 was reported . The value of 0.172 obtained for the present reaction system comes in between linear polymer molecules (0.167) and the hyperbranched polymers (0.18), which appears to be reasonable.…”