T.H. Kalantar, M. Ladika, G. Strandburg, A. Safir, S. Zong
Dow Chemical,
United States
Keywords: high throughput, polymer colloid, mechanical dispersion, polymeric stabilizer
Summary:
The Mechanical Dispersion (MD) process, a method of making low viscosity aqueous dispersions of polyolefins (and other polymers that do not emulsion polymerize), is enabled by a variety of dispersing materials, including small molecule surfactants and polymeric stabilizers such as ethylene-acrylic acid (EAA) polymers. The polymeric stabilizers are particularly useful at high temperature, but there is a limited range of EAA materials available commercially. The purpose of this preliminary study is to demonstrate that useful dispersing polymers can be prepared from hydrophobic (meth)acrylate/acrylamide monomers copolymerized with sulfonic acid functional moieties. Using high throughput polymer synthesis tools, the potassium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) was copolymerized with a series of hydrophobic (meth)acrylate/acrylamide monomers at a range of carbon number to charge ratios to prepare a series of candidate dispersing polymers. A small scale MD process was developed, employing a novel high shear but small scale impeller design, to screen the polymers for their ability to enable the formation of aqueous dispersions of polyolefin copolymers. The polymers were screened on the basis of high temperature water solubility, molecular weight and, using a novel small-scale MD process, for their ability to enable the dispersion of polyolefin resins to stable aqueous dispersions. Polymers with molecular weight 5,000 – 10,000 Da prepared from AMPS and t-octyl acrylamide, lauryl acrylate, and 2-etheylhexyl acrylate over a wide range of carbon number per charge appeared, in this preliminary work, to be effective as dispersion stabilizers. More extensive effort will be needed in order to elucidate detailed polymer structure-dispersion property relationships.