- Synthesis of pH- and thermoresponsive poly(2-n-propyl-2-oxazoline) based copolymers
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Polymers that possess lower critical solution temperature behavior such as poly(2-alkyl-2-oxazoline)s (PAOx) are interesting for their application as stimulus-responsive materials, for example in the biomedical field. In this work, we discuss the scalable and controlled synthesis of a library of pH- and temperature-sensitive 2-n-propyl-2-oxazoline P(nPropOx) based copolymers containing amine and carboxylic acid functionalized side chains by cationic ring opening polymerization and postpolymerization functionalization strategies. Using turbidimetry, we found that the cloud point temperature (CP) is strongly dependent on both the polymer concentration and the polymer charge (as a function of pH). Furthermore, we observed that the CP decreased with increasing salt concentration, whereas the CP increased linearly with increasing amount of carboxylic acid groups. Finally, turbidimetry studies in PBS-buffer indicate that CPs of these polymers are close to body temperature at biologically relevant polymer concentrations, which demonstrates the potential of P(nPropOx) as stimulus-responsive polymeric systems in, for example, drug delivery applications.
- Boerman, Marcel A.,Van Der Laan, Harry L.,Bender, Johan C. M. E.,Hoogenboom, Richard,Jansen, John A.,Leeuwenburgh, Sander C.,Van Hest, Jan C. M.
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p. 1573 - 1582
(2016/05/09)
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- Synthesis of poly(2-oxazoline)s with side chain methyl ester functionalities: Detailed understanding of living copolymerization behavior of methyl ester containing monomers with 2-alkyl-2-oxazolines
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Poly(2-oxazoline)s with methyl ester functionalized side chains are interesting as they can undergo a direct amidation reaction or can be hydrolyzed to the carboxylic acid, making them versatile functional polymers for conjugation. In this work, detailed studies on the homo- and copolymerization kinetics of two methyl ester functionalized 2-oxazoline monomers with 2-methyl-2-oxazoline, 2-ethyl-2-oxazoline, and 2-n-propyl-2-oxazoline are reported. The homopolymerization of the methyl ester functionalized monomers is found to be faster compared to the alkyl monomers, while copolymerization unexpectedly reveals that the methyl ester containing monomers significantly accelerate the polymerization. A computational study confirms that methyl ester groups increase the electrophilicity of the living chain end, even if they are not directly attached to the terminal residue. Moreover, the electrophilicity of the living chain end is found to be more important than the nucleophilicity of the monomer in determining the rate of propagation. However, the monomer nucleophilicity can be correlated with the different rates of incorporation when two monomers compete for the same chain end, that is, in copolymerizations.
- Bouten,Hertsen, Dietmar,Vergaelen, Maarten,Monnery, Bryn D.,Catak, Saron,Van Hest, Jan C. M.,Van Speybroeck, Veronique,Hoogenboom, Richard
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p. 2649 - 2661
(2015/10/12)
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- Method for inhibiting hydrate formation
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A method for inhibiting the formation of clathrate hydrates in a fluid having hydrate forming constituents is disclosed. More specifically, the method can be used in treating a petroleum fluid stream such as natural gas conveyed in a pipe to inhibit the formation of a hydrate restriction in the pipe. The hydrate inhibitors used for practicing the method are substantially water soluble polymers formed from a cyclic imino ether. Some examples of such inhibitors include various N-acyl polyalkyleneimines, such as N-acyl substituted polyethyleneimine, N-acyl substituted polypropyleneimine, N-acyl substituted polybutyleneimine, N-acyl substituted polypentyleneimine and copolymers thereof. Also, such N-acyl substituted polyalkyleneimines can be used in various ratios with other substantially water soluble polymers and copolymers. Preferably, a solvent such as water, brine, alcohol, or mixtures thereof is used to produce an inhibitor solution or mixture to facilitate treatment of the petroleum fluid stream.
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- Method for inhibiting hydrate formation
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A method for inhibiting the formation of clathrate hydrates in a fluid having hydrate forming constituents is disclosed. More specifically, the method can be used in treating a petroleum fluid stream such as natural gas conveyed in a pipe to inhibit the formation of a hydrate restriction in the pipe. The hydrate inhibitors used for practicing the method are substantially water soluble polymers formed from a cyclic imino ether. Such polymers may be ring closed cyclic imino ether ("CIE") polymers, ring opened CIE polymers, or combinations thereof. Some examples of ring opened CIE polymers include various N-acyl polyalkyleneimines produced by cationic polymerization, such as N-acyl substituted polyethyleneimine, N-acyl substituted polypropyleneimine, N-acyl substituted polybutyleneimine, N-acyl substituted polypentyleneimine and copolymers thereof. Ring closed CIE polymers may be derived from free radical or anionic polymerization of 2-alkenyl-2-oxazolines, 2-alkenyl-2-oxazines, and other cyclic imino ethers having an alkene functional group. Also, such ring closed and ring opened CIE polymers can be copolymerized with other substantially water soluble polymers or used in various ratios with other substantially water soluble polymers and copolymers. Preferably, a solvent such as water, brine, alcohol, or mixtures thereof is used to produce an inhibitor solution or mixture to facilitate treatment of the petroleum fluid stream.
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