Hyperbranched Polymers Formed through Irreversible Step Polymerization of AB2‐Type Monomer in a Continuous Flow Stirred‐Tank Reactor (CSTR)

Hyperbranched polymers formed through step polymerization of AB₂‐type monomer with equal reactivity for both B groups in a continuous flow stirred‐tank reactor (CSTR) are investigated theoretically. The weight fraction distribution at high molecular weight tail follows a power law, W (P ) ∝ P ^−1/ξ for ξ ≤ 0.5 with , where is the mean residence time. The degree of branching (DB) at the large degree of polymerization (P ) limit is DB _{P →∞} = 0.6 irrespective of the ξ‐value, which is larger than the case for the corresponding batch polymerization that gives DB _{P →∞} = 0.5. The relationship between the radius of gyration 〈s ²〉₀ and P shows that the hyperbranched polymers formed in a CSTR are very compact, and the 〈s ²〉₀‐values for large polymers are even smaller than the smallest possible case for a batch reactor with DB _{P →∞} = 1. For large polymers, the power law 〈s ²〉₀∝P ^1/3 holds, which is 〈s ²〉₀∝P ^1/2 for batch polymerization.