Aromatic−Aliphatic Polyesters with Tailored Degree of Branching Based on AB/AB₂and ABB*/AB₂Monomers

Abstract

The synthesis and characterization of aromatic−aliphatic polyesters with tailored degree of branching (DB), i.e. hyperbranched (hb), gradually branched, and linear polymers, are described. The dilute solution properties of polymers resulting from two different synthetic approaches are compared. The ABB*/AB2 approach leads to homopolymers with different DB based on the same AB2 monomer, 4,4-bis(4′-hydroxyphenyl)pentanoic acid, employing the protection of one phenolic group (B*) in the AB2 monomer followed by copolymerization with AB2 monomer at different molar ratios. Because of their identical chemical origin, well-tunable DB, comparable molar masses, an absence of aggregation in common solvents, and high refractive index increments, they are suitable as model systems in branching characterization. Their solution properties are compared to those of polymers obtained by the AB/AB2 approach. In order to study the influence of the end-groups on thermal and solution polymer properties, all terminal OH groups were modified with tert-butyldimethylsilyl chloride (SY-Cl). A different dependence of the thermal properties on branching was found for OH- and SY-terminated samples produced by the ABB*/AB2 approach. While the difference in the T g values between linear and hb structures was found to be 16 °C for SY-terminated samples, nearly identical values were obtained for OH-terminated linear and hb polyesters due to strong effect of hydrogen bond formation.

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“…It is extremely difficult to homogenize WPU matrix with silica nanoparticles just relying on the mechanical blending method. As we know, poly(ester amine) dendrimers have attracted considerable attentions because they could bring benefits of low viscosity, excellent miscibility, and highly branching molecular structures, which contain a large number of functional end groups [15–18]. All kinds of applications have been exploited for poly(ester amine) dendrimer, e.g., coating, medicine, and nanoengineering [19–21].…”

SANS Investigation of Global and Segmental Structures of Hyperbranched Aliphatic–Aromatic Polyesters

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“…Hyperbranched polyesters can be synthesized via various approaches but are most often prepared via AB 2 or A 2 + B 3 type step polymerizations 6–11. The resulting hyperbranched polymers contain hydroxyl and/or carboxylic acid functional groups at the linear and terminal structural units, which are amenable to postpolymerization modification and can be used to tune the thermal, solubility, and mechanical properties of these materials or to prepare core–shell type architectures.…”