Parallel kinetic investigation of 2‐oxazoline polymerizations with different initiators as basis for designed copolymer synthesis

Abstract

The systematical kinetic investigations of four 2‐substituted‐2‐oxazoline monomers with four initiators at two temperatures and four monomer/initiator ratios are described. To cover this broad range of variables (128 different combinations), an automated synthesizer was used to accelerate the investigations and to provide highly comparable results. With both gas chromatography and gel permeation chromatography, the livingness and the polymerization rates were determined for the different polymerizations. The resulting insights in the kinetics were used for the directed synthesis of truly random copolymers and copolymers with composition drift. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1830–1840, 2004

Systematic investigation of alkyl sulfonate initiators for the cationic ring-opening polymerization of 2-oxazolines revealing optimal combinations of monomers and initiators

“…Propagation occurs via nucleophilic attack of the monomer on the oxazolinium species, resulting in ring-opening and the formation of an amide by isomerization. Typical initiators are alkyl or benzyl halides including chlorides, [5] bromides [5] and iodides [6] or alkyl sulfonates such as p-toluenesulfonates (tosylates), [7] p-nitrobenzenesulfonates (nosylates) [8] and trifluoromethanesulfonates (triflates) [9].…”

Design Strategies for Functionalized Poly(2-oxazoline)s and Derived Materials

“…Schubert and co-workers prepared a library of 128 homopolymers of the composition pMeOx, pEtOx, pPhOx, and p n NonOx and ranged the reactivity of four different initiators for the corresponding CROP reactions, namely benzyl bromide, methyl triflate, methyl tosylate, and methyl iodide [21]. In terms of polymerization rates, the initiators that delivered methyl cations during the initiation were ranked methyl triflate > methyl tosylate > methyl iodide.…”

Poly(2‐oxazoline)s: Alive and Kicking

“…Optimization of the polymerization temperature, [30] initiator, [31] and concentration [32] finally led to optimal polymerization conditions for 2-ethyl-2-oxazoline (EtOx) to give full conversion after only 2 h polymerization time. [32] Although the high-throughput optimization of the polymerization conditions yielded this tremendous acceleration from several days to several hours, the resulting optimal polymerization procedure is not suitable for fast library preparation because of the very high monomer concentration of 8 M (which corresponds to %80 wt.-% monomer), which leads to very viscous polymerization mixtures.…”