Poly(tert-butyl methacrylate/styrene) Macroinitiators as Precursors for Organo- and Water-Soluble Functional Copolymers Using Nitroxide-Mediated Controlled Radical Polymerization

Abstract

Styrene/tert-butyl methacrylate (S/TBMA) mixtures, with initial TBMA molar feed compositions fTBMA,0 = 0.1−0.92, were copolymerized by nitroxide-mediated polymerization (NMP) in bulk at 90 °C using 10 mol % {tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino} nitroxide (SG1) relative to 2-({tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino}oxy)-2-methylpropionic acid unimolecular initiator (BlocBuilder) to form SG1-terminated macroinitiators. kpK values (kp = propagation rate constant, K = equilibrium constant) for S/TBMA increased significantly as fTBMA,0 increased, with kpK = (7.4 ± 0.03) × 10−7 to (5.4 ± 0.9) × 10−5 s−1. Copolymer reactivity ratios were rTBMA= 0.13−0.27 and rS = 0.43−0.59 using Fineman−Ross, Kelen−Tudos, and nonlinear least-squares fitting to the Mayo−Lewis terminal model. All S/TBMA copolymers (number-average molecular weight Mn = 4.5−15.6 kg mol−1) exhibited low polydispersities (Mw/Mn ≤ 1.30), and Mn exhibited linear behavior with conversion up to 25−40% and mon...