Synthesis of gradient copolysiloxanes by simultaneous copolymerization of cyclotrisiloxanes and mechanism for kinetics inverse between anionic and cationic ring‐opening polymerization

<jats:title>ABSTRACT</jats:title><jats:p>Trifluoropropylmethylsiloxane–phenylmethylsiloxane gradient copolysiloxanes were synthesized by anionic and cationic ring‐opening polymerization (ROP) of 1,3,5‐tris(trifluoropropylmethyl)cyclotrisiloxane ( <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/pola27921-math-0001.png" xlink:title="urn:x-wiley:0887624X:media:pola27921:pola27921-math-0001"/>) and phenylmethylcyclotrisiloxane ( <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/pola27921-math-0002.png" xlink:title="urn:x-wiley:0887624X:media:pola27921:pola27921-math-0002"/>). The analysis of reactivity ratios revealed that the reactivity of <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/pola27921-math-0003.png" xlink:title="urn:x-wiley:0887624X:media:pola27921:pola27921-math-0003"/> toward anionic ROP was higher than that of <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/pola27921-math-0004.png" xlink:title="urn:x-wiley:0887624X:media:pola27921:pola27921-math-0004"/>; however, <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/pola27921-math-0005.png" xlink:title="urn:x-wiley:0887624X:media:pola27921:pola27921-math-0005"/> exhibited lower reactivity compared with <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/pola27921-math-0006.png" xlink:title="urn:x-wiley:0887624X:media:pola27921:pola27921-math-0006"/> during the cationic ROP. AB and BAB type gradient copolymers were obtained because of a difference in the reactivity of the monomers. The microstructure of copolymers was characterized by <jats:sup>29</jats:sup>Si NMR spectroscopy, gel permeation chromatography, and differential scanning calorimetry. Furthermore, the mechanism for kinetics inverse of copolymerization was proposed based on the results of the optimized molecular configuration. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. <jats:bold>2016</jats:bold>, <jats:italic>54</jats:italic>, 835–843</jats:p>