Architectural copolymers of PAMAM dendrimers and ionic polyacetylenes

Novel, star-shaped copolymers have been prepared to study the resulting properties of the core-shell copolymers. While the shell was formed from rigid, conductive ionic polyacetylene (PAc) arms, semiflexible, spheroidal aliphatic poly(amidoamine) (PAMAM) dendrimers served as initiator cores. The synthesis was carried out;it room temperature by reacting the primary amino terminal groups of the generation three and four PAMAM dendrimers with N-methyl-2-ethynylpyridinium triflate in DMSO at different monomer/initiator ratios. Full surface functionalization of the amino groups was achieved at the 2EPyMeTf/PAMAM-NH2 = 4 monomer/terminal amino group ratio when the whole surface was; found to be completely covered with short rigid ionic acetylene chains giving macromolecular "sea urchins". Depending on the chain length of the polyacetylene,arms and the degree of dendrimer surface coverage, these core-shell polymers may be considered as functionalized dendrimers or dendrimer-initiated ionic polyacetylenes. The resulting products were characterized by FTIR, W-visible, H-1 and C-13 NMR spectroscopy, capillary electrophoresis, TEM, TGA, DSC, and conductivity measurements. Solid-state conductivity of the doped copolymer was found to be in the 10(-4)-10(-5) S/cm range due to the shorter conjugation length in the ionic polyacetylene shell. However thermal stability of the PAMAM dendrimer interior improved dramatically as a result of copolymer formation.