Temperature-responsive poly(tetrafluoroethylene) membranes grafted with branched poly(N-isopropylacrylamide) chains

Han, Chun-Chieh; Wei, Ta‐Chin; Wu, Chuan‐Shao; Liu, Ying‐Ling

doi:10.1016/j.memsci.2010.04.027

Cited by 15 publications

(2 citation statements)

References 31 publications

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“…One of the best-studied temperature-responsive polymers is PNIPAAM, which has a LCST of about 32 °C in bulk aqueous solution. However, the LCST of PNIPAAM is dependent on molecular weight, polymer concentration, and the presence of end-group functionalities. , Surfaces bearing PNIPAAM chains have also been widely investigated ,− for their temperature-dependent surface properties.…”

Section: Introductionmentioning

confidence: 99%

Tethered Poly(2-isopropyl-2-oxazoline) Chains: Temperature Effects on Layer Structure and Interactions Probed by AFM Experiments and Modeling

Liu

Linse³

et al. 2015

Langmuir

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Thermoresponsive polymer layers on silica surfaces have been obtained by utilizing electrostatically driven adsorption of a cationic-nonionic diblock copolymer. The cationic block provides strong anchoring to the surface for the nonionic block of poly(2-isopropyl-2-oxazoline), referred to as PIPOZ. The PIPOZ chain interacts favorably with water at low temperatures, but above 46 °C aqueous solutions of PIPOZ phase separate as water becomes a poor solvent for the polymer. We explore how a change in solvent condition affects interactions between such adsorbed layers and report temperature effects on both normal forces and friction forces. To gain further insight, we utilize self-consistent lattice mean-field theory to follow how changes in temperature affect the polymer segment density distributions and to calculate surface force curves. We find that with worsening of the solvent condition an attraction develops between the adsorbed PIPOZ layers, and this observation is in good agreement with predictions of the mean-field theory. The modeling also demonstrates that the segment density profile and the degree of chain interpenetration under a given load between two PIPOZ-coated surfaces rise significantly with increasing temperature.

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Section: Introductionmentioning

confidence: 99%

Tethered Poly(2-isopropyl-2-oxazoline) Chains: Temperature Effects on Layer Structure and Interactions Probed by AFM Experiments and Modeling

Liu

Linse³

et al. 2015

Langmuir

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“…In most cases, this temperature sensitivity reflects conformational changes of thermosensitive polymer chains attached to the surface. Surfaces bearing poly( N -substituted-acrylamide) chains have been widely investigated, focusing primarily on poly( N -isopropylacrylamide) (PNIPAM). , Temperature-responsive surfaces based on oligo(ethylene glycol)methacrylates and ethylene oxide- co -propylene oxide copolymers have been explored as well, with particular focus on their nonfouling characteristics that are useful in biomedical applications. Poly(2-alkyl-2-oxazolines), where the alkyl group is methyl, ethyl, or isopropyl, also possess nonfouling properties, yet there are only a few studies on their properties on surfaces.…”

Section: Introductionmentioning

confidence: 99%

Temperature-Dependent Adsorption and Adsorption Hysteresis of a Thermoresponsive Diblock Copolymer

Dédinaité

Winnik

et al. 2014

Langmuir

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A nonionic-cationic diblock copolymer, poly(2-isopropyl-2-oxazoline)60-b-poly((3-acrylamidopropyl)trimethylammonium chloride)17, (PIPOZ60-b-PAMPTMA17), was utilized to electrostatically tether temperature-responsive PIPOZ chains to silica surfaces by physisorption. The effects of polymer concentration, pH, and temperature on adsorption were investigated using quartz crystal microbalance with dissipation monitoring and ellipsometry. The combination of these two techniques allows thorough characterization of the adsorbed layer in terms of surface excess, thickness, and water content. The high affinity of the cationic PAMPTMA17 block to the negatively charged silica surface gives rise to a high affinity adsorption isotherm, leading to (nearly) irreversible adsorption with respect to dilution. An increase in solution pH lowers the affinity of PIPOZ to silica but enhances the adsorption of the cationic block due to increasing silica surface charge density, which leads to higher adsorption of the cationic diblock copolymer. Higher surface excess is also achieved at higher temperatures due to the worsening of the solvent quality of water for the PIPOZ block. Interestingly, a large hysteresis in adsorbed mass and other layer properties was observed when the temperature was cycled from 25 to 45 °C and then back to 25 °C. Possible causes for this temperature hysteresis are discussed.

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Stimuli‐Responsive Membranes

Wee

Bai

2013

Encyclopedia of Membrane Science and Technology

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Recent advances in design and preparation of stimuli‐responsive membranes (SRMs), and their uses in areas such as molecular filtration, engineering separation, controlled capture/release, etc. are presented and critically assessed in this article. The underlying principles for actualization and response of various types of SRMs are first reviewed, with respect to their constituent stimuli‐responsive polymers or chemical functionality. Then, the various membrane preparation methods and processes that facilitate the incorporation of the stimuli‐responsive polymers, molecules, or additives to alter the membrane properties (e.g., permeability and selectivity) are discussed, in response to either the change in environmental conditions (e.g., solution pH and temperature) or the presence of an externally applied field (e.g., electric field, magnetic field). Design parameters that play important roles in shaping the manner and extent at which the trigger response from SRMs is actualized are also discussed and elucidated. Potential engineering applications that integrate such novel membranes or associated systems are also presented to illustrate their vast potential in tackling various health and sustainability issues.

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Temperature-responsive poly(tetrafluoroethylene) membranes grafted with branched poly(N-isopropylacrylamide) chains

Cited by 15 publications

References 31 publications

Tethered Poly(2-isopropyl-2-oxazoline) Chains: Temperature Effects on Layer Structure and Interactions Probed by AFM Experiments and Modeling

Tethered Poly(2-isopropyl-2-oxazoline) Chains: Temperature Effects on Layer Structure and Interactions Probed by AFM Experiments and Modeling

Temperature-Dependent Adsorption and Adsorption Hysteresis of a Thermoresponsive Diblock Copolymer

Stimuli‐Responsive Membranes

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