Facile Synthesis of Functional Periodic Copolymers: A Step toward Polymer-Based Molecular Arrays.

A step-growth strategy was investigated for preparing functional periodic copolymers. Functional heterotelechelic α-alkyne, ω-azido poly(styrene-co-N-substituted maleimide) precursors (Mn ≈ 2500 g·mol−1) have been prepared and subsequently polymerized by copper-catalyzed azide−alkyne cycloaddition (CuAAC). These precursors have been first synthesized by sequential atom transfer radical copolymerization of styrene and a N-substituted maleimide (i.e., benzyl maleimide, N-(2-(amino-tBOC)-ethylen)-maleimide, or benzyl N,N-maleoylglycinate) initiated by 3-(1,1,1-trimethylsilyl)-2-propynyl 2-bromo-2-methylpropanoate. In this approach, styrene homopolymerization was first started, and a discrete amount of the maleimide comonomer (e.g., 1 equiv as compared to initiator) was added when styrene half-conversion was reached. This controlled maleimide addition resulted in the formation of well-defined polystyrene segments containing a functional maleimide in the middle of their chains (i.e., in average 1 unit per chai...