Solubility and Thermoresponsiveness of PMMA in Alcohol-Water Solvent Mixtures

Abstract

To reduce the environmental burden of polymer processing, the use of non-toxic solvents is desirable. In this regard, the improved solubility of poly(methyl methacrylate) (PMMA) in ethanol/water solvent mixtures is very appealing. In this contribution, detailed investigations on the solubility of PMMA in alcohol/water solvent mixtures are reported based on turbidimetry measurements. PMMA revealed upper critical solution temperature transitions in pure ethanol and ethanol/water mixtures. However, around 80 wt-% ethanol content a solubility maximum was observed for PMMA as indicated by a decrease in the transition temperature. Moreover, the transition temperatures increased with increasing PMMA molar mass as well as increasing polymer concentration. Careful analysis of both heating and cooling turbidity curves revealed a peculiar hysteresis behaviour with a higher precipitation temperature compared with dissolution with less than 60 wt-% or more than 90 wt-% ethanol in water and a reverse hysteresis behaviour at intermediate ethanol fractions. Finally, the transfer of poly(styrene)-block-poly(methyl methacrylate) block copolymer micelles from the optimal solvent, i.e. aqueous 80 wt-% ethanol, to almost pure water and ethanol is demonstrated.

Temperature Induced Solubility Transitions of Various Poly(2-oxazoline)s in Ethanol-Water Solvent Mixtures

“…The observed behavior for PentOx, a steep decrease in cloud points from 60 to 70 wt% ethanol is similar to the observed solubility transitions of poly(methyl methacrylate) in water-ethanol solvent mixtures [30,51]. This peculiar solubility behavior is due to the clustering of water molecules in ethanol rich solutions.…”

Polymers with upper critical solution temperature behavior in alcohol/water solvent mixtures

“…This has been ascribed to the preferential waterhydrogen bonding to the ester moieties of the polymer as most of the water is present as single, non-clustered molecules in this ethanol concentration regime leading to favorable water-polymer hydrogen bonding (Scheme 1). [49,53,66,73] The formation of this hydration-shell around the carbonyl groups of the polymer is supported by small angle neutron scattering indicating the presence of a single deuterated water molecule per PMMA repeat unit. [53] The solubility of PMMA decreases with higher water content due to the formation of larger water clusters that need to be broken for hydration of the polymers.…”

“…The disaggregation of the water-water clusters has been suggested to facilitate the solubility of poly(methyl methacrylate) (PMMA) and rendered the maximum solubility of the polymer in the solvent mixture with the highest fraction of individual water molecules. [65,66] The solvent mixtures of methanol and water have also been investigated by neutron-diffraction revealing that a major fraction of monomeric water molecules is present at a methanol fraction of 0.7. [67] Similarly, with isopropanol or n-propanol molar fraction of 0.7 in water, the tetrahedral-like network structure of water is scarcely formed.…”

Fabrication of a microfluidic chip based on the pure polypropylene material

“…4 PMMA is not porous, but the glass transition temperature of the PMMA material is about 106 C, 5 which is not high enough for high-temperature sterilization ($121 C) in a biomedical process. Common organic chemical reagents, such as ethanol 6,7 and ethyl acetate, 8 may undergo reactions with the PMMA material; this limits the commercial applications (such as in reaction tubes) of the PMMA material in biomedical and other analytical chemistry elds. PMMA has poor resistance to many other chemicals due to its easily hydrolyzable ester groups.…”