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Nothdurft K, Müller DH, Mürtz SD, Meyer AA, Guerzoni LPB, Jans A, Kühne AJC, De Laporte L, Brands T, Bardow A, Richtering W. Is the Microgel Collapse a Two-Step Process? Exploiting Cononsolvency to Probe the Collapse Dynamics of Poly- N-isopropylacrylamide (pNIPAM). J Phys Chem B 2021; 125:1503-1512. [PMID: 33503378 DOI: 10.1021/acs.jpcb.0c10430] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Many applications of responsive microgels rely on the fast adaptation of the polymer network. However, the underlying dynamics of the de-/swelling process of the gels have not been fully understood. In the present work, we focus on the collapse kinetics of poly-N-isopropylacrylamide (pNIPAM) microgels due to cononsolvency. Cononsolvency means that either of the pure solvents, e.g., pure water or pure methanol, act as a so-called good solvent, leading to a swollen state of the polymer network. However, in mixtures of water and methanol, the previously swollen network undergoes a drastic volume loss. To further elucidate the cononsolvency transition, pNIPAM microgels with diameters between 20 and 110 μm were synthesized by microfluidics. To follow the dynamics, pure water was suddenly exchanged with an unfavorable mixture of 20 mol% methanol (solvent-jump) within a microfluidic channel. The dynamic response of the microgels was investigated by optical and fluorescence microscopy and Raman microspectroscopy. The experimental data provide unique and detailed insight into the size-dependent kinetics of the volume phase transition due to cononsolvency. The change in the microgel's diameter over time points to a two-step process of the microgel collapse with a biexponential behavior. Furthermore, the dependence between the two time constants from this biexponential behavior and the microgel's diameter in the collapsed state deviates from the square-power law proposed by Tanaka and Fillmore [ J. Chem. Phys. 1979, 70, 1214-1218]. The deviation is discussed considering the adhesion-induced deformation of the gels and the physical processes underlying the collapse.
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Affiliation(s)
- Katja Nothdurft
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - David H Müller
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstr. 8, 52062 Aachen, Germany
| | - Sonja D Mürtz
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Anna A Meyer
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Luis P B Guerzoni
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52074 Aachen, Germany
| | - Alexander Jans
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52074 Aachen, Germany
| | - Alexander J C Kühne
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52074 Aachen, Germany
| | - Laura De Laporte
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52074 Aachen, Germany.,Institute of Technical and Macromolecular Chemistry, RWTH Aachen, Worringerweg 1-2, 52074 Aachen, Germany
| | - Thorsten Brands
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstr. 8, 52062 Aachen, Germany
| | - André Bardow
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstr. 8, 52062 Aachen, Germany.,Department of Mechanical and Process Engineering, ETH Zürich, Tannenstr. 3, 8092 Zürich, Switzerland
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.,DWI-Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52074 Aachen, Germany
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Hoppe Alvarez L, Rudov AA, Gumerov RA, Lenssen P, Simon U, Potemkin II, Wöll D. Controlling microgel deformation via deposition method and surface functionalization of solid supports. Phys Chem Chem Phys 2021; 23:4927-4934. [PMID: 33620358 DOI: 10.1039/d0cp06355j] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Soft matter at solid-liquid interfaces plays an important role in multiple scientific disciplines as well as in various technological fields. For microgels, representing highly interesting soft matter systems, we demonstrate that the preparation method, i.e. the way how the microgel is applied to the specific surface, plays a key role. Focusing on the three most common sample preparation methods (spin-coating, drop-casting and adsorption from solution), we performed a comparative study of the deformation behavior of microgels at the solid-liquid interface on three different surfaces with varying hydrophilicities. For in situ visualization of the deformation of pNIPMAM microgels, we conducted highly sensitive 3D super resolution fluorescence microscopy methods. We furthermore performed complementary molecular dynamics simulations to determine the driving force responsible for the deformation depending on the surface and the deposition method. The combination of experiments and simulations revealed that the simulated equilibrium structure obtained after simulation of the completely dry microgel after deposition is retained after rehydration and subsequent fluorescent imaging.
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Affiliation(s)
- Laura Hoppe Alvarez
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - Andrey A Rudov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation and DWI - Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, D-52056 Aachen, Germany
| | - Rustam A Gumerov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation and DWI - Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, D-52056 Aachen, Germany
| | - Pia Lenssen
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - Ulrich Simon
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1 a, D-52056 Aachen, Germany
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation and DWI - Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, D-52056 Aachen, Germany and National Research South Ural State University, Chelyabinsk 454080, Russian Federation
| | - Dominik Wöll
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
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Saunders JE, Chen H, Brauer C, Clayton M, Loock HP. Two distinct mechanisms upon absorption of volatile organic compounds into siloxane polymers. SOFT MATTER 2018; 14:2206-2218. [PMID: 29431812 DOI: 10.1039/c7sm02234d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The response of polysiloxane materials to volatile organic compounds (VOCs) including benzene, toluene, ethylbenzene, and toluene (BTEX), as well as cyclohexane, acetone, methanol and isopropanol is studied using thin film large-angle refractometry. Refractive index and thickness changes are measured to quantify the diffusion rate and partition coefficients associated with the absorption and desorption of VOC vapours into polydimethylsiloxane (PDMS) and polydiphenylsiloxane (PDPS) - PDMS copolymer films. Absorption of volatile solvent vapours into siloxane polymers is found to follow two distinct mechanisms with different absorption rates. These mechanisms are also associated with different excess volumes of mixing and may be accompanied by a polymer restructuring step.
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Affiliation(s)
- John E Saunders
- Department of Chemistry, Queen's University Kingston, ON K7L 3N6, Canada.
| | - Hao Chen
- Department of Chemistry, Queen's University Kingston, ON K7L 3N6, Canada.
| | - Chris Brauer
- Department of Chemistry, Queen's University Kingston, ON K7L 3N6, Canada.
| | - McGregor Clayton
- Department of Chemistry, Queen's University Kingston, ON K7L 3N6, Canada.
| | - Hans-Peter Loock
- Department of Chemistry, Queen's University Kingston, ON K7L 3N6, Canada.
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Begum R, Farooqi ZH, Khan SR. Poly(N-isopropylacrylamide-acrylic acid) copolymer microgels for various applications: A review. INT J POLYM MATER PO 2016. [DOI: 10.1080/00914037.2016.1180607] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Saunders JE, Chen H, Brauer C, Clayton M, Chen W, Barnes JA, Loock HP. Quantitative diffusion and swelling kinetic measurements using large-angle interferometric refractometry. SOFT MATTER 2015; 11:8746-8757. [PMID: 26458138 DOI: 10.1039/c5sm02170g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The uptake and release of sorbates into films and coatings is typically accompanied by changes of the films' refractive index and thickness. We provide a comprehensive model to calculate the concentration of the sorbate from the average refractive index and the film thickness, and validate the model experimentally. The mass fraction of the analyte partitioned into a film is described quantitatively by the Lorentz-Lorenz equation and the Clausius-Mosotti equation. To validate the model, the uptake kinetics of water and other solvents into SU-8 films (d = 40-45 μm) were explored. Large-angle interferometric refractometry measurements can be used to characterize films that are between 15 μm to 150 μm thick and, Fourier analysis, is used to determine independently the thickness, the average refractive index and the refractive index at the film-substrate interface at one-second time intervals. From these values the mass fraction of water in SU-8 was calculated. The kinetics were best described by two independent uptake processes having different rates. Each process followed one-dimensional Fickian diffusion kinetics with diffusion coefficients for water into SU-8 photoresist film of 5.67 × 10(-9) cm(2) s(-1) and 61.2 × 10(-9) cm(2) s(-1).
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Affiliation(s)
- John E Saunders
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
| | - Hao Chen
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
| | - Chris Brauer
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
| | - McGregor Clayton
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
| | - Weijian Chen
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
| | - Jack A Barnes
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
| | - Hans-Peter Loock
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
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Guo S, Gao Y, Wei M, Zhang QM, Serpe MJ. Controlled release kinetics from a surface modified microgel-based reservoir device. J Mater Chem B 2015; 3:2516-2521. [DOI: 10.1039/c4tb01964d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Deposition of Si-based layers on top of a polymer-based “drug” delivery device allows fine-tuning of “drug” release kinetics.
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Affiliation(s)
- Siyuan Guo
- Department of Chemistry
- University of Alberta
- Edmonton
- Canada
| | - Yongfeng Gao
- Department of Chemistry
- University of Alberta
- Edmonton
- Canada
| | - Menglian Wei
- Department of Chemistry
- University of Alberta
- Edmonton
- Canada
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Gao Y, Zago GP, Jia Z, Serpe MJ. Controlled and triggered small molecule release from a confined polymer film. ACS APPLIED MATERIALS & INTERFACES 2013; 5:9803-9808. [PMID: 24063561 DOI: 10.1021/am4029894] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A device composed of a poly (N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgel layer sandwiched between two thin Au layers (all on a glass support) was used as a novel platform for controlled and triggered small molecule delivery. Tris (4-(dimethylamino)phenyl)methylium chloride (Crystal Violet, CV), which is positively charged, was loaded into the microgel layer of the device and released in a pH dependent fashion, at a rate that could be controlled by the thickness of the Au layer coating the microgels. Specifically, at pH 6.5 (above the pKa for AAc) the microgels were negatively charged, promoting the strong interaction between the CV and the microgels, hindering its release from the layer. At pH 3.0 the microgel's AAc groups are protonated making the microgel mostly neutral, allowing CV to be released from the microgel layer at a rate that depends on the thickness of the Au covering the microgels. Specifically, devices with thin Au overlayers on the microgel layer allow CV to be released from the device faster than devices with thick Au overlayers. The ability to tune the release rate with pH and Au layer thickness is advantageous for developing implantable devices that are capable of releasing small molecule drugs in a triggered and controlled fashion.
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Affiliation(s)
- Yongfeng Gao
- Department of Chemistry, University of Alberta , Edmonton, Alberta, Canada T6G 2G2
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Responsive polymers for analytical applications: A review. Anal Chim Acta 2013; 789:17-32. [DOI: 10.1016/j.aca.2013.05.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/01/2013] [Accepted: 05/04/2013] [Indexed: 11/24/2022]
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