Rheological properties of hydroxyl‐terminated and end‐capped aliphatic hyperbranched polyesters

Abstract

The rheological behavior of two series of aliphatic hyperbranched (HB) polyesters, based on 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) and di-trimethylol propane (Di-TMP) as a tetrafunctional core, was studied. The effect of the size (pseudogeneration number, from second to eight) and structure on the melt rheological properties was investigated for a series of hydroxylterminated HB polyesters. In addition, the influence of the nature and degree of modification of the terminal OH groups in a series of fourth-generation polyesters end-capped with short and long alkyl chains and some aryl groups on the rheological properties was analyzed. The time-temperature superposition procedure was applied for the construction of master curves and for the analysis of the rheological properties of HB polyesters. The data obtained from WLF analysis of the HB polyesters showed that the values of the thermal coefficient of expansion of free volume a f and the fractional free volume at the glass transition temperature, f g , increase with increasing size of the HB polyesters. It was shown that the modified HB polyesters exhibited lower T g and T G 0 5G 00 temperatures, above which viscous became dominant over elastic behavior. From an analysis of the master curves of the modified HB polyesters, it was observed that with increasing degree of modification, both storage and loss modules and complex dynamic viscosity and apparent energy for viscoelastic relaxation decrease, because of reduced intermolecular hydrogen interactions. They do not exhibit a plateau of rubbery behavior, which confirms that no entanglements are present and that the molar masses are below the critical molar mass.

Value-added ground work of polyester film forming co-binder for flexographic solvent based printing inks

“…This is due to the specific branched structure of hyperbranched oligoester that have a smaller hydrodynamic volume compared with a linear polymer of the same molar mass and/or the interaction of a large number of polar functional groups with the column packing, especially in tetrahydrofuran (THF). In addition, the presence of side reactions, such as cyclization, ether formation, decarboxylation and deactivation of carboxylic groups, and self-condensation during melt polycondensation led to a broadening of the molar mass distribution and limits the attainable molar mass [32] .…”

Architecture - behaviour - properties relationship in Star-shaped MPA-PMMA and MPA-PS hyper-branched copolymers

“…Dunjic et al demonstrated that the rheological properties of aliphatic hyperbranched MPA polyesters are dependent on the pseudogeneration number and nature and degree of modification of the terminal OH groups in a series. These dependencies are associated with the volume size of shaped and hydrogen bond interactions [5]. In the same line, Adrjanowicz et al studied the inter-and intra-molecular glass-transition dynamics in MPA hyperbranched polyesters of second, third, and fourth generations.…”

“…Branched polymers, including dendrimers and hyperbranched polymers, display important differences with regard to their linear counterparts. Branched entities contain high-density of localized polymer chains resulting in unique physical properties, such as high functionality and low viscosity as compared to their linear analogues with similar molecular weight opening a range of possibilities for application of these polymers in several areas of science and technology [1,2], such as coatings, resin formulations, additives, drug delivery, cosmetics, membranes, and lithography [3][4][5][6].…”