Water-dispersible tetrablock copolymer synthesis, aggregation, nanotube preparation, and impregnation

A tetrablock copolymer polyisoprene-block-poly(tert-butyl acrylate)-block-poly[(2-cinnamoyloxyethyl methacrylate)-ran-(2-hydroxyethyl methacrylate)]-block-poly(solketal methacrylate), or PI-b-PtBA-b-P(CEMA-r-HEMA)-b-PSMA, was synthesized and characterized. After PSMA hydrolysis to poly(glyceryl methacrylate), or PGMA, the tetrablock formed cylindrical aggregates in water with a PGMA corona and an insoluble part consisting of PI and P(CEMA-r-PHEAM) core-shell cylinders that sandwich a PtBA thin layer. Water-dispersible nanotubes were obtained after the cross-linking of the P(CEMA-r-HEMA) layer and cleavage of the PI cores with ozone. Both nanotubes containing some ozonized PI fragments and the cross-linked PI-b-PtBA-b-P(CEMA-r-HEMA)-b-PGMA cylindrical aggregates sorbed Pd2+ from dimethylformamide as a result of the pi-allyl complex formation between Pd2+ and the PI double bonds. The sorbed Pd2+ was reduced to Pd nanoparticles, and the particles were made to overlap by catalyzing further Pd deposition on them in an electroless Pd plating bath. These polymer/metal hybrid nanofibers with conductive cores may be useful as nanocables or as a catalyst for reagents that can permeate the P(CEMA-r-PHEMA) layer.