All-aromatic hyperbranched polyesters with phenol and acetate end groups: synthesis and characterization

Abstract

This report describes the synthesis of all-aromatic hyperbranched polyesters with phenol and acetate end groups. The synthesis was based on the melt condensation of tbe A¡B monomers 3,5-bis-(trimethylsiloxy)benzoyl chloride (2) and 3,5-diacetoxybenzoic acid (3). The trimethylsilyl groups of the polyesters from monomer 2 are hydrolyzed during workup, resulting in polymers with phenol terminal groups. Although the acetate groups of polymers prepared from 3 are quite stable and remain in the polymer, conditions were found where they could be hydrolyzed to give a phenolic polymer similar to that obtained from 2. The special structure of the monomers results in highly branched (hyperbranched) materials with a high number of terminal groups. Comparison of Mark-Houwink plots of linear polystyrene and a hyperbranched polyester sample and Mark-Houwink "a" values of less than 0.5 for numerous samples were consistent with highly branched structures. These polyesters are noncrystalline and are thermally stable to at least 350 °C. As predicted for such step-growth polymerizations, the molecular weight distributions broadened significantly at high conversions.

Tuning the Solubility of Copper Complex in Atom Transfer Radical Self-Condensing Vinyl Polymerizations to Control Polymer Topology via One-Pot to the Synthesis of Hyperbranched Core Star Polymers

“…In early syntheses of hyperbranched polymers, reactions of monomers ABx (x ≥ 2) where the A and B groups can condense with each other exclusively resulted in step-growth polymerization becoming a predominant method. Thus, an enormous numbers of different types of hyperbranched polymers have been synthesized, including polyphenylenes [8,9], polyesters [10][11][12], polyether [13,14], polysiloxysilanes [15], and polybenzamides [16,17], a variety of which have been reviewed [18,19]. Through conventional step-growth mechanisms, hyperbranched polymers can be synthesized in one-pot, avoiding the need for multiple reactions with protection, deprotection, and purification steps typically required for constructing perfect dendrimers, but with the drawback of large polydispersities in molecular weight and structure.…”

Computer simulations of hyperbranched polymers: The influence of the Wiener index on the intrinsic viscosity and radius of gyration

“…Within other efforts, a monotonic increase of ͓ ͔ with N more akin to the Mark-Houwink behavior of linear polymers was observed, regardless of the degree of branching. [7][8][9][10] The conflicting message of these measurements may in part be due to the difficulty associated with characterizing these materials using size exclusion chromatography ͑SEC͒. The noted polydispersities in N and DB complicate the interpretation of SEC applied to HPs since a highly branched molecule with a large value of N can have the same hydrodynamic volume as a less branched or linear molecule with a smaller value of N.…”

Synthesis and Liquid Crystalline Properties of Hyperbranched Aromatic Polyesters Consisting of Azoxybenzene Mesogens and Polymethylene Spacers

“…This value is not far from the theoretically predicted value of 0.5 for very high molar mass polymers. Turner et al 42,43 and Sunder et al 44 earlier prepared hyperbranched polyesters that they reported had DB values of 0.50-0.59. Therefore, it is concluded Poly (12, 2) possesses a hyperbranched structure.…”