Thermodynamic and Kinetic Characterization of Colloidal Polymers of <i>N</i>-Isopropylacrylamide and Alkyl Acrylic Acids for Optical pH Sensing
Copolymers of <i>N</i>-isopropylacrylamide (NIPA) and alkyl acrylic acids that swell and shrink in response to pH were prepared by dispersion polymerization at 35 °C using <i>N</i>-isopropylacrylamide (transduction monomer), methylenebisacrylamide (crosslinker), 2-dimethoxy-2...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-03-01
|
| Series: | Molecules |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1420-3049/30/7/1416 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850188096296976384 |
|---|---|
| author | James T. Moulton David Bruce Richard A. Bunce Mariya Kim Leah Oxenford Snyder W. Rudolf Seitz Barry K. Lavine |
| author_facet | James T. Moulton David Bruce Richard A. Bunce Mariya Kim Leah Oxenford Snyder W. Rudolf Seitz Barry K. Lavine |
| author_sort | James T. Moulton |
| collection | DOAJ |
| description | Copolymers of <i>N</i>-isopropylacrylamide (NIPA) and alkyl acrylic acids that swell and shrink in response to pH were prepared by dispersion polymerization at 35 °C using <i>N</i>-isopropylacrylamide (transduction monomer), methylenebisacrylamide (crosslinker), 2-dimethoxy-2-phenyl-acetophenone (initiator), <i>N</i>-<i>tert</i>-butylacrylamide (transition temperature modifier), and acrylic acid, methacrylic acid, ethacrylic acid, and propacrylic acid (functional comonomer). The diameter of the microspheres of the copolymer varied between 0.5 µm and 1.0 µm. These microspheres were cast into hydrogel membranes prepared by mixing the pH-sensitive swellable polymer particles with aqueous polyvinyl alcohol solutions followed by crosslinking the polyvinyl alcohol with glutaric dialdehyde for use as pH sensors. Large changes in the turbidity of the polyvinyl alcohol membrane monitored using a Cary 6000 UV–visible absorbance spectrometer were observed as the pH of the buffer solution in contact with the membrane was varied. Polymer swelling was reversible for many of these NIPA-based copolymers. The buffer capacity, ionic strength, pH, and temperature of the buffer solution in contact with the membrane were systematically varied to provide an in-depth pH profile of each copolymer. A unique aspect of this study was the investigation of the response of the NIPA-based polymers to changes in the pH of the solution in contact with the membrane at low buffer concentrations (0.5 mM). The response rate and the reversibility of polymer swelling even at low buffer capacity suggest that NIPA-based copolymers can be coupled to an optical fiber for pH sensing in the environment. We envision using these polymers to monitor rising acidity levels in the ocean due to water that has become enriched in carbon dioxide that endangers shell-building organisms by reducing the amount of carbonate available to them. |
| format | Article |
| id | doaj-art-ac1827e48ece471dbed6dd3bf47c6966 |
| institution | OA Journals |
| issn | 1420-3049 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj-art-ac1827e48ece471dbed6dd3bf47c69662025-08-20T02:15:58ZengMDPI AGMolecules1420-30492025-03-01307141610.3390/molecules30071416Thermodynamic and Kinetic Characterization of Colloidal Polymers of <i>N</i>-Isopropylacrylamide and Alkyl Acrylic Acids for Optical pH SensingJames T. Moulton0David Bruce1Richard A. Bunce2Mariya Kim3Leah Oxenford Snyder4W. Rudolf Seitz5Barry K. Lavine6Department of Chemistry, Oklahoma State University, Stillwater, OK 74078, USADepartment of Chemistry, Oklahoma State University, Stillwater, OK 74078, USADepartment of Chemistry, Oklahoma State University, Stillwater, OK 74078, USADepartment of Chemistry, Oklahoma State University, Stillwater, OK 74078, USADepartment of Chemistry, Oklahoma State University, Stillwater, OK 74078, USADepartment of Chemistry, University of New Hampshire, Durham, NH 03824, USADepartment of Chemistry, Oklahoma State University, Stillwater, OK 74078, USACopolymers of <i>N</i>-isopropylacrylamide (NIPA) and alkyl acrylic acids that swell and shrink in response to pH were prepared by dispersion polymerization at 35 °C using <i>N</i>-isopropylacrylamide (transduction monomer), methylenebisacrylamide (crosslinker), 2-dimethoxy-2-phenyl-acetophenone (initiator), <i>N</i>-<i>tert</i>-butylacrylamide (transition temperature modifier), and acrylic acid, methacrylic acid, ethacrylic acid, and propacrylic acid (functional comonomer). The diameter of the microspheres of the copolymer varied between 0.5 µm and 1.0 µm. These microspheres were cast into hydrogel membranes prepared by mixing the pH-sensitive swellable polymer particles with aqueous polyvinyl alcohol solutions followed by crosslinking the polyvinyl alcohol with glutaric dialdehyde for use as pH sensors. Large changes in the turbidity of the polyvinyl alcohol membrane monitored using a Cary 6000 UV–visible absorbance spectrometer were observed as the pH of the buffer solution in contact with the membrane was varied. Polymer swelling was reversible for many of these NIPA-based copolymers. The buffer capacity, ionic strength, pH, and temperature of the buffer solution in contact with the membrane were systematically varied to provide an in-depth pH profile of each copolymer. A unique aspect of this study was the investigation of the response of the NIPA-based polymers to changes in the pH of the solution in contact with the membrane at low buffer concentrations (0.5 mM). The response rate and the reversibility of polymer swelling even at low buffer capacity suggest that NIPA-based copolymers can be coupled to an optical fiber for pH sensing in the environment. We envision using these polymers to monitor rising acidity levels in the ocean due to water that has become enriched in carbon dioxide that endangers shell-building organisms by reducing the amount of carbonate available to them.https://www.mdpi.com/1420-3049/30/7/1416optical pH sensingpH-induced polymer swelling<i>N</i>-isopropylacrylamidenonionic polymer swelling |
| spellingShingle | James T. Moulton David Bruce Richard A. Bunce Mariya Kim Leah Oxenford Snyder W. Rudolf Seitz Barry K. Lavine Thermodynamic and Kinetic Characterization of Colloidal Polymers of <i>N</i>-Isopropylacrylamide and Alkyl Acrylic Acids for Optical pH Sensing Molecules optical pH sensing pH-induced polymer swelling <i>N</i>-isopropylacrylamide nonionic polymer swelling |
| title | Thermodynamic and Kinetic Characterization of Colloidal Polymers of <i>N</i>-Isopropylacrylamide and Alkyl Acrylic Acids for Optical pH Sensing |
| title_full | Thermodynamic and Kinetic Characterization of Colloidal Polymers of <i>N</i>-Isopropylacrylamide and Alkyl Acrylic Acids for Optical pH Sensing |
| title_fullStr | Thermodynamic and Kinetic Characterization of Colloidal Polymers of <i>N</i>-Isopropylacrylamide and Alkyl Acrylic Acids for Optical pH Sensing |
| title_full_unstemmed | Thermodynamic and Kinetic Characterization of Colloidal Polymers of <i>N</i>-Isopropylacrylamide and Alkyl Acrylic Acids for Optical pH Sensing |
| title_short | Thermodynamic and Kinetic Characterization of Colloidal Polymers of <i>N</i>-Isopropylacrylamide and Alkyl Acrylic Acids for Optical pH Sensing |
| title_sort | thermodynamic and kinetic characterization of colloidal polymers of i n i isopropylacrylamide and alkyl acrylic acids for optical ph sensing |
| topic | optical pH sensing pH-induced polymer swelling <i>N</i>-isopropylacrylamide nonionic polymer swelling |
| url | https://www.mdpi.com/1420-3049/30/7/1416 |
| work_keys_str_mv | AT jamestmoulton thermodynamicandkineticcharacterizationofcolloidalpolymersofiniisopropylacrylamideandalkylacrylicacidsforopticalphsensing AT davidbruce thermodynamicandkineticcharacterizationofcolloidalpolymersofiniisopropylacrylamideandalkylacrylicacidsforopticalphsensing AT richardabunce thermodynamicandkineticcharacterizationofcolloidalpolymersofiniisopropylacrylamideandalkylacrylicacidsforopticalphsensing AT mariyakim thermodynamicandkineticcharacterizationofcolloidalpolymersofiniisopropylacrylamideandalkylacrylicacidsforopticalphsensing AT leahoxenfordsnyder thermodynamicandkineticcharacterizationofcolloidalpolymersofiniisopropylacrylamideandalkylacrylicacidsforopticalphsensing AT wrudolfseitz thermodynamicandkineticcharacterizationofcolloidalpolymersofiniisopropylacrylamideandalkylacrylicacidsforopticalphsensing AT barryklavine thermodynamicandkineticcharacterizationofcolloidalpolymersofiniisopropylacrylamideandalkylacrylicacidsforopticalphsensing |