A new approach to graft siloxanes to alkyds

Abstract

The effect of oil length of alkyds and substitution of siloxane backbone has been studied for alkyd-siloxane hybrids. A series of nine alkydsiloxane hybrids were synthesized by either varying the oil length of the alkyd or the siloxane backbone substitution. Three linseed oil-based alkyds with either a long, medium, or short oil length were grafted with three hydride-terminated siloxanes substituted with methyl, cyclopentyl, or cyclohexyl groups. A hydrocoupling reaction was used to couple the telechelic siloxane with the hydroxyl functionality of the alkyds using Wilkinson's catalyst. The reaction was monitored by the disappearance of siloxane hydride signal using Fourier transform infrared. Characterization of siloxane-alkyd hybrids was performed using 1 H-NMR, 13 C-NMR, and gel permeation chromatography. The hybrids were formulated with a Co, Zr, and Ca drier package and auto-oxidatively cured without using any solvent. The tensile, viscoelastic, and coating properties were evaluated for the cured films. The crosslink density, flexibility, and reverse impact resistance were found to increase as a function of oil length. Tensile modulus, elongation-to-break, glass transition temperature, drying time, and fracture toughness decreased with increase in oil length. For the alkyd-siloxane hybrids, the mechanical and rheological properties were dependant on the size of the substituents. The larger-sized cyclopentyl and cyclohexyl groups resulted in better mechanical and rheological properties than the methyl-containing siloxanes.

Hybrid alkyds, the glowing route to reach cutting-edge properties?

“…One of the limitation of the alkyd is their poor outdoor weatherability that could be improved by adding silicones which possess excellent moisture and UV-degradation resistance. 16,107 Indeed, silicones, also called polysiloxanes, are a popular group of synthetic polymers providing hydrophobicity to coatings thanks to their siloxane groups (Si-O-Si). 108 Moreover, silicone containing polymers are attractive because they exhibit low surface tension, excellent electrical properties, good weatherability, non-flammability, high gas permeability, good thermal and chemistry stability, as well as corrosion protection.…”

“…In order to overcome this drawback, siloxanes were grafted to alkyds, thus the microphase separation was reduced, leading to better overall properties. 16 Several routes were investigated to create covalent bonds between constituents. Alkyd resins can be post-functionalized by silicon compounds thanks to their remaining hydroxyl groups or by chemically modified unsaturations present in their long aliphatic chains in order to obtain silicone-modified alkyd resins.…”

“…1,4 One of the first alkyd hybrid system was the synthesis of silicone-alkyd resin reported in 1947. 16 Modifying alkyd resins with polyamide resins affect viscosity and yield thixotropic alkyd resins. 2 To improve drying time of alkyd resins, exhibit better abrasion resistance, toughness, chemical and UV resistance, hybridization with urethane has been developed.…”

Fatty acid based waterborne air drying epoxy ester resin for coating applications

“…The synthesized resin was reacted with 0.7 mole di-ethanolamine at 65 ± 2 • C for 1 h, neutralized with phosphoric acid solution and stirring continued for 6 h. The prepared waterborne resin was dried using cobalt based driers (blend of lead (0.3% of metal), cobalt (0.03% of metal) in the ratio 10:1 (Lead: cobalt)). This cobalt and lead based driers are most extensively used for drying waterborne coatings [23][24][25][26][27]. The viscosity and non volatile matter (NVM) of resin were adjusted with water.…”

SAXS and DSC studies on the structural characteristics of siliconized s-triazine glassy hybrid materials

“…Different composites comprising s-triazine and organosilicone substrates are exploited in coatings, adhesives, cosmetics and other products [16][17][18][19][20]. In a recent study, we concluded that s-triazine (▲) can be conveniently bonded to a series of organosilicone moieties (RSiO 1.5 , R 2 SiO, R = CH 3 and C 6 H 5 ) through -O-connections to form intact oligomeric glassy materials, Fig.…”