Modification, characterization and application of hyperbranched polyarylates

Hyperbranched polymers are polymers with highly branched, yet non-crosslinked structures. In this work, the existing laboratory polymerization procedure was scaled up by a suspension method to synthesize hyperbranched poly(5-acetoxy isophthalic acid) of high molecular weight. A method of modifying the residual acyl groups of this polymer with different reagents was also established. Especially, the synthesis of monofunctional etherimide facilitated the compatiblization of the hyperbranched polyarylate with commercial polyetherimide. All modified polymers were characterized by FTIR, ;The structural profiles of hyperbranched polyarylate were then investigated. The measurement of the degree of branching indicated that these macromolecules had uniform chemical structures. Solution static light scattering revealed that the hyperbranch polyarylates had very compact structures, the dimension of which remained stable regardless of different polymer-solvent interactions. Light scattering, NMR with LSR (Lanthanide Shift Reagent) as well as molecular simulation showed that molecules such as LSR ;n;The rheological properties of hyperbranched polymer and its blends presented the most promising aspect for future applications. The relaxation spectrum of hyperbranched polyarylate did not exhibit a plateau zone that is an indication of chain entanglement for linear polymers. This observation was true even for samples with molecular weight over 10;Finally, the mechanical property of blends of etherimide modified hyperbranched polyarylate and polyetherimide was investigated. While the tensile modulus of the material was enhanced, the toughness was drastically reduced due to the lack of entanglement between the macromolecules. Possible methods for improving this drawback were proposed.