Poly(aryleneethynylene) type polymers composed of p-phenylene and 2,5-thienylene units. Analysis of polymerization conditions and terminal group in relation to the mechanism of the polymerization and chemical and optical properties of the polymer

Palladium-catalyzed polycondensation between p-diethynylbenzene (HC=C-Ph-C=CH) and 2, 5-diiodo-3-hexylthiophene (I-Th(Hex)-I) has been carried out under various conditions by changing the polymerization temperature, medium, and added amines. The polycondensation gives the polymer (PAE-1) with a M-n of about 3 x 10(4) (by GPC, polystyrene standards) and an [eta] value of 0.8 dL g(-1). By using neat NEt3 as the medium, the polymerization proceeds fast. H-1-NMR spectroscopic analysis indicates that oligomeric PAE-1 obtained at short polymerization time has a C-I bond (-Th(Hex)-I bond) as the major terminal group, which is consistent with results of the basic Pd-catalyzed C-C coupling reaction. The C-I terminal bond of oligomeric PAE-1 reacts with 1, 3, 5-triethynylbenzene and 1, 2, 4, 5-tetraethynylbenzene to give polymers with M-n values of 8.7 x 10(5) and 2.3 x 10(6) (by GPC), respectively, and the polymers are considered to have star-type structures. All the polymers show two (main and sub) photoluminescence PL peaks at 456 +/- 3 and 486 +/- 2 nm. The C=C bond of PAE-1 is susceptible to trans-type hydrogenation with SMEAH (sodium bis(2-methoxyethoxy)aluminum hydride) and DIBAL (diisobutylaluminum hydride) as well as to chlorofluorination by a mixture of N-chlorosuccinic imide and a pyridinium salt of (HF)(x)F-.