Dendritic Polymers Based on Urethane Chemistry – Syntheses and Applications

Abstract

The development of dendritic polymers, including dendrimers as well as hyperbranched or highly branched polymers, is rapidly growing in all fields of polymer chemistry. This review article focuses on dendritic polymers based on urethane chemistry as a principle of construction, summarizing synthetic approaches based on isocyanate chemistry as well as on isocyanate free processes. Furthermore, scientific publications and patent literature were investigated to provide a comprehensive overview of applications where dendritic polyurethanes show their specific chemical and physical potential.

Preparation of Novel Hydrolyzing Urethane Modified Thiol-Ene Networks

“…TGA data and film hardness measurements suggested an increase in water absorption for formulations containing the oligomer. Relative rates of hydrolysis obtained in an NMR study of closely related networks, further supports this assumption by revealing that the inclusion of the urethane segment to the network increases the rate of hydrolysis as monitored by 19 F NMR. This phenomenon contributed to the additional hydrogen bonding elements and polar functionality brought to the film with the addition of the urethane segment.…”

“…As another means to explore the hydrolysis rates of our thiol-ene networks, the group prepared a new series of networks containing a modified fluorinated hydrolyzable monomer, which could be detected by 19 F NMR. Table 3 describes the series, which consisted of two distinct model systems: fluorinated networks and fluorinated blends.…”

“…A small change in network density of these samples is expected upon polymerization, as the functionality of the hydrolyzable monomer is altered from F4 to F3. Since no detectable difference in polymerization rate is observed between the vinyl and allyl monomers, only vinyl monomers are investigated by 19 F NMR and no allyl systems were explored. modified to contain 1 fluorinated hydrolyzable group and 3 ene groups for network formation, an F3 monomer; the remaining 2 network samples contain mixtures of ene-monomers, Vinyloxy-F was added to tetrafunctional vinyloxy-100 to create (2) ½ vinyloxy-F, allowing the sample to contain half the amount of fluorinated material, and finally (3) ene-modified urethane segment was added at 25 wt %; last 3 entries are blends (4-6), 2,2,3,3-tetrafluoro-1-propanol is added to vinyloxy-100 vinyloxy-75 formulations to create uncrosslinked blend compositions for comparison; b -formulations were varied to produce several concentrations of fluorinated samples, so comparisons could be drawn.…”

“…19 F analysis was performed on a 400 MHz NMR, and integration ratios were based on the 2,2 F peak of 2,2,3,3-tetrafluoro-1-propanol at −126 δ versus the internal standard at −75 δ. The concentration of 2,2,3,3-tetrafluoro-1-propanol in the reaction chamber was extrapolated from a calibration curve produced from varied concentrations in of 2,2,3,3-tetrafluoro-1-propanol (FOH) with a constant concentration of trifluoroacetic acid internal standard and analyzing by 19 F NMR integrations ratios. This study was repeated varying fluorinated sample formulations.…”

“…Analogous to the thiol-ene system, a wide array of commercially available monomers exist to allow for tailoring of the resulting polymer properties [19,20]. Urethane bonds form quickly through the reaction of isocyanate (NCO) and alcohol (OH) functional groups to produce relatively inexpensive and durable coatings, having strong mechanical properties, good abrasion resistance, and thermal stability [21].…”