SYNTHESIS AND CHARACTERIZATION OF A POLYPHENYLACETYLENE WITH DENDRON PENDANTS

Polymerization of a phenylacetylene monomer bearing a dendron moiety was carried out by using a rhodium complex Rh[(nbd)Cl_2]_2 as catalyst.The structure of the resultant was characterized with infrared(IR),nuclear magnetic resonance(NMR),and UV-Visible absorption spectroscopic techniques;the experimental data confirmed the generation of the expected polyphenylacetylene derivative(P1) with dendron pendants.P1 was soluble in common organic solvents such as chloroform,N,N-dimethylformamide oxide,and tetrahydrofurran(THF),and its average molecular weight was about 57300.The steric repulsion of between the bulky dendritic side chains make the polymer main-chain take a stereoregular cis-cisoid conformation.Consequently,P1 exhibits a pronounced shoulder at around 440 nm in the absorption spectrum its THF solution.Meanwhile,the bulky dendrons around the polymer main-chain protect the main-chain from thermal-induced decomposition via the jacket effect,thus P1 lost 5% of its weight at a temperature of 295℃,which is about 70℃ higher than its parent polymer,or polyphenylacetylene.