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1611262 
Journal Article 
UCST-type behavior of poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) in aliphatic alcohols: solvent, co-solvent, molecular weight, and end group dependences 
Roth, PJ; Jochum, FD; Theato, P 
2011 
1 
Soft Matter
ISSN: 1744-683X 
ROYAL SOC CHEMISTRY 
CAMBRIDGE 
7 
6 
2484-2492 
English 
WOS:000288162500033 
Poly[oligo(ethylene glycol) methyl ether methacrylate]
(POEGMA) is shown to possess insoluble-soluble transitions (UCST-type phase behavior) in a large
variety of aliphatic alcohols. Samples of different molecular weights ranging from 5 kg mol(-1)
to 23 kg mol(-1) prepared by the RAFT process and featuring different end groups at each end were
analyzed by cloud point measurements. Transitions occurred sharply and were fully reversible. The
UCST was found to increase with an increasing molecular weight. Hydrophobic (alkyl chain) end
groups were found to lower the critical temperature in isopropanol, while rigid aromatic end
groups raised the transition temperature. In ternary mixtures of isopropanol/chloroform/POEGMA,
the UCST decreased with an increasing chloroform concentration, with 10 vol% of chloroform
accounting for a 30 degrees C drop. In mixtures of isopropanol/hexane/POEGMA, the cloud point
increased significantly only with hexane concentrations above 30 vol%, at which level a 2 degrees
C transition temperature increase was found. Addition of water to isopropanol solutions had a
strong effect, with 1 vol% of water causing a decrease of the transition temperature of 12.5
degrees C. With an increasing chain length of the solvent, the cloud point increased, while a
branching of the hydrocarbon chains lowered the cloud point. Samples of 23 kg mol(-1) POEGMA were
for instance found to have cloud points of 22.0 degrees C in ethanol, 35.7 degrees C in
isopentanol, and 75.4 degrees C in dodecanol.