Ultraviolet-Curable Cycloaliphatic Polyesters Containing Spiroacetal Moieties for Application as Powder Coatings

Abstract

Thermosetting cycloaliphatic powder coatings that exhibit good weatherability, corrosion resistance, and mechanical properties have been desired for some time. Unfortunately, most cycloaliphatic resins have glass transition temperatures (T gs) that are too low for powder coating applications. In this study, a series of ultraviolet (UV)-curable, cycloaliphatic polyesters was synthesized from 3,9-bis­(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]­undecane (spiroglycol), 1,4-cyclohexanedimethanol, and 1,4-cyclohexanedicarboxylic acid. The oligomers were characterized by 1H nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, gel-permeation chromatography, and differential scanning calorimetry. The T g value, the tensile strength, and the modulus of the crosslinked polyesters systematically increased with the spiroglycol (SPG) loading level. Dynamic mechanical analysis experiments highlighted structure–property relationships and showed evidence of secondary relaxations at around −44 °C. These β-relaxations were attributed to conformational transitions of the cycloaliphatic rings. The oligomers that contained 30 and 45 mol % SPG had T gs that were suitable for powder coating applications. As such, they were formulated into UV-curable powder coatings. Coated test panels were evaluated in a salt spray chamber (ASTM B117) and a QUV weatherometer. The impact resistance, adhesion, and pencil hardness properties of the coatings were also evaluated. When compared to conventional (aromatic-based) controls, the cycloaliphatic powder coatings exhibited comparable weatherability, corrosion resistance, and T gs along with superior impact resistance, substrate adhesion, and resistance to yellowing. These findings suggest that the cycloaliphatic powder coatings would be good alternatives to aromatic-based systems that are used in exterior durable clear coat applications.

Ion-Conductive and Mechanically Stable Copolymer Electrolytes Based on Aliphatic Carbonates

“…We clearly observed these ν SNS , ν SO2 , and ν CF3 peaks at 1066, 1139, and 1201 cm –1 , and the peak intensities rose with increasing LiTFSI concentration. The peak of the C–O–C group for PEO is around 1109 cm –1 , and the peak shifts to lower wavenumber when the C–O–C group interacts with the Li ions. , For the polyester copolymer with SPG, the stretching vibration of the C–O–C group of SPG is observed at 951 and 1089 cm –1 . For the neat branch -P­(DMC/TEG/SPG) polymer, the peaks at 955 and 1090 cm –1 probably derive from SPG.…”

“…42 We clearly observed these ν SNS , ν SO2 , and 43,44 For the polyester copolymer with SPG, the stretching vibration of the C−O−C group of SPG is observed at 951 and 1089 cm −1 . 45 For the neat branch-P(DMC/TEG/SPG) polymer, the peaks at 955 and 1090 cm −1 probably derive from SPG. When the salt concentration increased with 60 wt %, these peaks were down-shifted to 951 and 1088 cm −1 , and the intensity fell.…”

A Rational Design of Bio‐Derived Disulfide CANs for Wearable Capacitive Pressure Sensor

“…[38] Spiroacetals, consisting of two twisted rings sharing the same tetrahedral carbon atom, have sparked interest in material production, for example, stimuliresponsive material, owing to their high glass transition temperature, high impact resistance, excellent mechanical properties, good UV-light stability, and advantageous environmental friendliness. [39,40] They are commonly synthesized by sugarderived polyol and lignin-derived aldehydes. Among all, sprioglycol(SG) is particularly attractive for its facile production and commercial availability, and its diol nature allows it to strengthen the polymer via introducing the rigid covalent twisted-ring motifs into the network.…”

“…Among all, sprioglycol(SG) is particularly attractive for its facile production and commercial availability, and its diol nature allows it to strengthen the polymer via introducing the rigid covalent twisted-ring motifs into the network. [39,41,42] Additionally, Caffeic acid (CA), originating from sunflower seed and coffee beans, structure-wisely contains a natural phenolic catechol group and an aliphatic carboxylic functionality, conferring this molecule the capability to undergo versatile non-covalent interactions, for example, metalcatechol coordination. The catechol chemistry, widely adopted in natural organisms like mussels and worms, leads to a controllable sacrificial metal-catecholate crosslinking with mechanical strength integration but does not sacrifice elongation/toughness.…”

Facile Sustainable Synthesis of Polyester-Polycarbonate and Effects of the Carbonate on Thermal, Mechanical, and Transparency Properties

“…Hence, CHDM is introduced into the polyester-polycarbonate to improve the thermal and optical properties of the copolymer. − Unlike most of the existing polyester-polycarbonate syntheses, this work simplified the reaction process by controlling the feed ratio and the gradual temperature increase, which achieves controllable one-pot synthesis. − A series of amorphous copolyesters (PCCTs) were synthesized by using DMC derived from carbon dioxide (CO 2 ) with contents ranging from 20 to 100 mol %, and the combination of rigid carbonate and aromatic ester units effectively destroys the crystallization properties and endows excellent optical properties. Moreover, the reaction mechanism, molecular structures, and thermal properties of the copolyester were examined, and the copolyester was blown into film to evaluate its applicability in packaging materials.…”