Synthesis of trifunctional graft polymer polyether polyols employing a silica based gel as non-aqueous dispersant

Abstract

Currently, the PU industry is developing new products with enhanced physical, mechanical and structural properties. One of the specialties that is attracting more and more attention from managers and enterprises all over the world are the PUs based on polymer polyether polyols (graft polyols). In this work, the synthesis of graft polyols was developed employing a non-aqueous dispersant (NAD) based on silica gel, which contains in its chemical structure segments with a great affinity for the solid polymeric particles and other segment having a strong affinity for the hydroxyl groups of the liquid polyol. The combination of both polar and non-polar characteristics ensures the stability of the resulting polymer dispersion and prevent the sedimentation and the coalescence of the polymer particles. By using this NAD it was possible to synthesize trifunctional polymer polyether polyol (PPP) from Styrene and containing up to 38.69 wt.% of solids. The optimal reaction conditions have been stablished using a concentration of 1.5 wt.% NAD, 4 wt.% of initiator respect to the monomer amount and a polymerization temperature of 80ºC. The viscosity of the optimal PPP (1930 mPa•s) and the particle size (dv0.5 of 5.427 m and dn0.5 of 1.711 m) were in the range of graft polyols available in the market for similar solids content, with the additional advantage of employing a lower quantity of NAD and a softer reaction temperature than those employed in the industrial process (110ºC).

The role of vinyl terminated silanes for producing highly concentrated polystyrene slurries in a single step process

“…According to previously reported works, this type of dispersant has been demonstrated to be effective for stabilizing PS particles in polyol media due to the creation of hydrophilic silanol groups 44,69 . Therefore, three reactions were carried out modifying the amount of CS, from 0.5 to 2.5 wt.%, keeping the 3.0 wt.% of SDS as ideal concentration of dispersing agent.…”

“…Indicating that the SDS remained in the solid material after the drying process. After the complete degradation of PS, the residue was attributed to the unburned SDS and the new formation of the highly thermal stable copolymer PS linkage with silicon groups 44 .…”

“…Our research group has recently developed a non-aqueous dispersant (NAD) based on functionalized silica containing vinyl terminated groups, which can be anchored to hydrophilic surfaces by Si-OH bonding, whereas the hydrophobic vinyl terminated groups reacted with styrene monomer, favouring the PS particle dispersion in oily media 44 . Utilizing this concept, silica materials could be exploited as surfactants of hydrophobic particles in watery media, since hydrophilic Si-OH bonds can be created outside the surface of a hydrophobic material, such as PS.…”