Poly(2,6-dimethyl-1,4-phenylene oxide), commonly known as PPO is in a class of high performance thermoplastic with good high temperature properties and excellent hydrolytic stability. Post-polymerization functionalization (PPF) is an important way to modify and improve PPO properties for dielectric, membrane and energy applications. Among the chemical transformations that have been utilized to structurally modify PPO, radical bromination is by far the most popular method used because of the ease in operation and scalability of the reaction it can offer. Among various reaction conditions evaluated, we found that bromination with N-bromosuccinimide(NBS)/azo-2,2’-isobutyronitrile (AIBN) in nonpolar solvents such as carbon tetrachloride and chlorobenzene affords brominated PPOs (Br-PPOs) containing almost exclusive benzyl bromide up to 80mol% of functionality. Herein, three types of sulfonylated PPOs, i.e. CH3SO2-, C6H5SO2-, and CF3SO2-PPOs, are prepared by nucleophilic substitution of Br-PPOs with methanesulfinate, benzenesulfinate and trifluoromethanesulfinate anions, respectively, as shown in Figure 1. The degree of functionality (DOF) varies from 25mol% to 80mol%. The successful functionalization of PPOs is confirmed by ATR-IR and NMR results. All the PPOs except the pristine PPO powder are amorphous according to WAXD and DSC measurements. Decrease of molecular weights with increasing DOF is observed probably due to the chain scission during the bromination. CH3SO2-PPO films demonstrate the best hygromorphic actuation in agreement with their DOF-dependent curvature in a humidity chamber.

Hygromorphic films of sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) derivatives

2019 Fall National Meeting

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