The tutorial will be a guided tour for the cyclization of a,w-telechelic polymers. Particular emphasis will be given on the controlling kinetic parameters that determine the molecular weight dependence for cyclization and the efficiency of forming mono-cyclic polymers. A derivation for the well-known Jacobson-Stockmayer equation will be given, and an empirical relationship between cyclization and multiblock formation based on the diffusion of chain ends (i.e. the Encounter Pair Model) will be compared to experimental data. Derivations for the differential equations found in kinetic simulations will be described, focusing on the effect of feed rates on cyclic efficiency. This has significance in the scale-up of such a synthetic process for the utilization in potential applications. A description of the topology of unwanted higher molecular weight species found during the synthesis will also be given. The rate constant K (= kc/kl) can be readily determined from the Jacobson-Stockmayer equation. Cyclization of a single polymer chain depends on the chain end-to-end distance between the reactive groups on either end of its random coil. When the chain ends diffuse to be within a capture radius (or volume) with rate coefficient kc1, a covalent bond can form through a chemical reaction at k2, or the chain ends can diffuse apart at k-1 (Scheme 1A). Such an 'encounter controlled' or 'diffusion controlled' process allows the equilibrium cyclization probability to be determined following the derivation by Jacobson and Stockmayer only when k-1 >> k2.

Tutorial on the kinetic percepts for cyclization of α,[omega]-telechelic polymers

245th National Meeting (2013)

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