Journal of Polymer Science Part A: Polymer Chemistry, Vol.49, No.4, 986-994, 2011
Synthesis of a Variety of Star-Shaped Polybenzamides via Chain-Growth Condensation Polymerization with Tetrafunctional Porphyrin Initiator
A variety of well-defined tetra-armed star-shaped poly(N-substituted p-benzamide)s, including block poly(p-benzamide)s with different N-substituents, and poly(N-substituted m-benzamide)s, were synthesized by using porphyrin-cored tetra-functional initiator 2 under optimized polymerization conditions. The initiator 2 allowed discrimination of the target star polymer from concomitantly formed linear polymer by-product; by means of GPC with UV detection, and the polymerization conditions were easily optimized for selective synthesis of the star polybenzamides. Star-shaped poly(p-benzamide) with tri(ethylene glycol) monomethyl ether (TEG) side chain was selectively obtained by polymerization of phenyl 4-{2-[2-(2-ME hoxyethoxy)ethoxy]ethylaminolbenzoate (1b') with 2 at -10 degrees C in the case of [1b'](0)/[2](0) = 40 and at 0 degrees C in the case of [1b(0)](0)/[2](0) = 80. Star-shaped poly(p-benzamide) with 4-(octyloxy)benzyl (OOB) substituent was obtained only when methyl 4-[4-(octyloxy)benzylamino]benzoate (1c) was polymerized at 25 degrees C at [1c](0)/[2](0) = 20. On the other hand, star-shaped poly(m-benzamide)s with N-butyl, N-octyl, and N-TEG side chains were able to be synthesized by polymerization of the corresponding meta-substituted aminobenzoic acid alkyl ester monomers 3 at 0 degrees C until the ratio of [3](0)/[2](0) reached 80. However, star-shaped poly(m-benzamide)s with the 008 group were contaminated with linear polymer even when the feed ratio of the monomer 3d to 2 was 20. The UV-visible spectrum of an aqueous solution of star-shaped poly(p-benzamide) with TEG side chain indicated that the hydrophobic porphyrin core was aggregated. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 986-994, 2011
Keywords:chain-growth condensation polymerization;living polymerization;molecular weight distribution/molar mass distribution;polyamides;polycondensation;porphyrin;star polymers