Related Experiment Video
Updated: May 2, 2026

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Terminal index: a new way for precise description of topologic structure of highly branched polymers derived from A2
1Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education, Department of Applied Chemistry, School of Science, Northwestern Polytechnical University , Xi'an, 710072, P. R. China.
Abstract:
Terminal index (TI) was presented as a new characteristic parameter for quantitative description of branched and cyclic topology of highly branched soluble polymers derived from A2 + B3 stepwise polymerization. TI is defined as the ratio of terminal units of an A2 + B3 type highly branched polymer to those in its perfect hyperbranched counterpart. TI is concisely represented as T/(D + L), which can be conveniently calculated from a quantitative NMR spectrum. The model of soluble A2 + B3 type polymers is suggested as an intermediate between multicyclic polymers and perfect hyperbranched polymers. The TI ranges between 0 and 1 where a higher TI indicates a perfect hyperbranched topology while a low TI indicates a multicyclic structure. The analysis of soluble A2 + B3 type polyesters and polycarbosilanes as model polymers demonstrates that TI as a more precise parameter, along with degree of branching, can be generally applied to understand the fine topology of highly branched polymers derived from A2 + B3 polymerization.
Related Concept Videos
Polymer Classification: Architecture
Radical Chain-Growth Polymerization: Chain Branching
Molecular Weight of Step-Growth Polymers
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
Characteristics and Nomenclature of Copolymers
Step-Growth Polymerization: Overview
Many natural and synthetic polymers are produced by...
Cationic Chain-Growth Polymerization: Mechanism

