Dynamical mechanical analysis of photocrosslinked hyperbranched urethane acrylates

Abstract

A series of acrylate functionalized samples based on hyperbranched hydroxy-terminated polyesters with different molecular weights and different degrees of acrylation were synthesized. The obtained urethane acrylates were slightly yellow viscose liquids. Their composition was characterized by FTIR and 1H-NMR spectroscopy and their molecular weights were measured by GPC. All the synthesized samples were diluted with 25 wt.% 1,4-butanediol dimethacrylate (BDDM). The rheological properties of the uncured samples and the dynamic mechanical properties of the UV cured samples were examined. All the samples exhibit Newtonian behavior, which indicates the absence of physical entanglements in these polymers. The viscosity increases with increasing number of acrylic groups permolecule. The glass transition temperature of the UV cured samples increases with increasing the number of acrylic groups permolecule. The value of the storage modulus in the rubber-elastic plateau and the cross-link density increase with increasing number of acrylic groups permolecule. The formed networks are inhomogeneous and the residual unsaturation is the highest in the samples with the largest number of acrylic groups per molecule.

Photoreactive hyperbranched urethane acrylates modified with a branched saturated fatty acid

“…The synthesis and properties of urethane acrylates based on aliphatic hyperbranched polyesters have been described in previous papers [26][27][28][29]. This paper represents the continuation of that work.…”

Synthesis and Characterization of UV-curable Hyperbranched Urethane Acrylate

“…The 1 H-NMR spectrum of the HBUA was used to calculate the degree of acrylation (DA) by comparing the signal intensities of the protons of the methylene groups adjacent to the hydroxyl endgroups, the protons of the methylene groups bound to oxygen from the ester groups, and the protons of the acrylate groups [14][15][16] .…”

“…There is a broad peak at about 4.3 ppm, which is an overlap peak associating with the methylene groups bound to oxygen in the ester groups, designated as Ha, Hb, and Aest. There are two peaks at 5.6 and 6.1 ppm assigned to the acrylate groups, designated as Hc [14][15][16] . According to the calculation method offered in the literature [14,15] , the degree of acrylation (DA) of HBUA is 79.8%, which indicates that 13 of the 16 hydroxyl groups in the H 2 0 molecule react with the NCO groups of IPDI=HEMA.…”

“…There are two peaks at 5.6 and 6.1 ppm assigned to the acrylate groups, designated as Hc [14][15][16] . According to the calculation method offered in the literature [14,15] , the degree of acrylation (DA) of HBUA is 79.8%, which indicates that 13 of the 16 hydroxyl groups in the H 2 0 molecule react with the NCO groups of IPDI=HEMA. This degree of acrylation is probably because the reactivity of the OH endgroups of the H 2 0 decreases due to steric hindrance and some of the OH groups don't react with the NCO groups of IPDI=HEMA.…”

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

“…The changes in the rheological parameters, such as the storage modulus ( G ′) and loss modulus ( G ″), the complex dynamic viscosity (η*), and tanδ with frequency and temperature were followed. The insight into the rheological behavior of hydroxyl terminated and end‐capped HB polyesters at different temperatures and deformations, allows one to tailor rheological properties with simple end‐group modification, and to define the potential application of these functionalized materials, especially in the field of coatings …”