Control of gradient copolymer composition in ATRP using semibatch feeding policy

Controlled/living radical copolymerization (CLRcoP) operated in a batch process is subject to composition drifting and thus produces spontaneous gradient copolymer. The composition distribution along the chain length of individual chains is solely determined by the reactivities of comonomers and the as-synthesized product is uncontrolled. Design of the composition vs. chain length profile provides a new route for developing polymer- materials with tailor-made properties. Presented in this article is a theoretical mainframe used for- the control over- composition distribution along the chain length in atom transfer radical copolymerization. The control is based on a semibatch reactor technology with programmed comonomer feeding rates. Illustrated are three copolymerization model systems with representative reactivity ratios. The targeted composition distribution profiles are uniform, linear gradient, parabolic gradient, hyperbolic gradient, and di-block and tri-block distributions. (c) 2006 American Institute of Chemical Engineers AIChE J, 53: 174-186, 2007.