Polysiloxanes with pendant benzimidazole units have been prepared by free radical thiolene coupling reactions of 2-(2-benzimidazolyl)ethanethiol and vinyl-functional polysiloxanes. The latter polymers were prepared by anionic ring opening copolymerization of 1,3,5,7-tetramethyl-1,3,5,7tetravinylcyclosiloxane and 1,3,5-hexamethylcyclosiloxane. Copolymers with different degrees of benzimidazole functionality were conveniently obtained by varying the monomer ratios. The coupling reaction was found to be very efficient, and the vinyl groups were completely consumed, as confirmed by NMR and FTIR spectroscopy. The glass transition temperature (T g) of the benzimidazole functional copolymers increased dramatically with the benzimidazole content at low contents to reach a plateau value just above 50 °C at a content of approximately 33 mol % benzimidazole functional siloxane residues in the copolymer. Conductivity measurements carried out at 60 and 140 °C indicated that the level of polymer segmental mobility, and thus the Tg, was the most decisive parameter for the proton conductivity at low temperatures (60 °C), while the benzimidazole concentration was more important at elevated temperatures (140 °C). A conductivity of 7 × 10 -6 S/cm was reached at 140 °C by a polysiloxane carrying 57 mol % benzimidazolegrafted siloxane residues under completely anhydrous conditions.

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Background: Dual neutralization of IL-4 and IL-13 is a promising therapeutic approach for asthma and allergy. Results: Knobs-into-holes IgG1 and IgG4 bispecific antibodies targeting both cytokines were developed. Conclusion: Bispecific antibodies of both isotypes have comparable in vitro potencies, in vivo pharmacokinetics, and lung partitioning. Significance: Further extension of knobs-into-holes technology to human IgG4 isotype as reported here provides greater options for therapeutics.

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