In-situ characterization of the temperature-sensitive swelling behavior of poly(N-isopropylacrylamide) brushes by infrared and visible ellipsometry

Furchner, Andreas; Bittrich, Eva; Uhlmann, Petra; Eichhorn, Klaus‐Jochen; Hinrichs, Karsten

doi:10.1016/j.tsf.2012.10.135

Cited by 18 publications

(24 citation statements)

References 26 publications

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“…Figure 6B,D show that the refractive index of all layers increases when T approaches the LCST, and this is consistent with the decreased thickness of the film, because a more densely packed phase is forming due to the collapse of the chains and expulsion of water molecules from the layer (de-swelling). Our results are in good qualitative agreement with previous studies for the PNIPAm reference [42,43] while some differences can be found for the grafted architecture. Synytska and coworkers [25] compared the swelling of PNIPAm with graft P(OEGMA-MEO 2 MA) and P(OEGMA-OPGMA) polymer brushes and measured higher swelling for PNIPAm compared to the layers with graft architecture.…”

Section: Characterization Of the Modified Surfacessupporting

confidence: 92%

Thermo-Responsive Polymer Brushes with Side Graft Chains: Relationship Between Molecular Architecture and Underwater Adherence

Sidoli

Tee

Raguzin

et al. 2019

IJMS

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During the last few decades, wet adhesives have been developed for applications in various fields. Nonetheless, key questions such as the most suitable polymer architecture as well as the most suitable chemical composition remain open. In this article, we investigate the underwater adhesion properties of novel responsive polymer brushes with side graft chain architecture prepared using "grafting through" approach on flat surfaces. The incorporation in the backbone of thermo-responsive poly(N-isopropylacrylamide) (PNIPAm) allowed us to obtain LCST behavior in the final layers. PNIPAm is co-polymerized with poly(methyl ethylene phosphate) (PMEP), a poloyphosphoester. The final materials are characterized studying the surface-grafted polymer as well as the polymer from the bulk solution, and pure PNIPAm brush is used as reference. PNIPAm-g-PMEP copolymers retain the responsive behavior of PNIPAm: when T > LCST, a clear switching of properties is observed. More specifically, all layers above the critical temperature show collapse of the chains, increased hydrophobicity and variation of the surface charge even if no ionizable groups are present. Secondly, effect of adhesion parameters such as debonding rate and contact time is studied. Thirdly, the reversibility of the adhesive properties is confirmed by performing adhesion cycles. Finally, the adhesive properties of the layers are studied below and above the LCST against hydrophilic and hydrophobic substrates.Int. J. Mol. Sci. 2019, 20, 6295 2 of 23 but it has been demonstrated that these proteins contain a variety of chemical functionalities, being particularly rich in 3,4-dihydroxyphenylalanine (l-DOPA), amino groups, and phosphates [2]. This variety of functionalities allows the mussel to provide different kind of interactions, therefore promoting adhesion against several organic and inorganic surfaces [3]. Another sessile organism known for its underwater adhesion is the sandcastle worm. This animal is able to build its shell made of sand grains and mineral particles using a rapid-set glue or cement; in-depth studies pointed out that the components of this glue are highly charged proteins, mainly anionic polyphosphates and cationic polyamines [4,5]. When these charged proteins are mixed together, a phase separation occurs due to complex coacervation between oppositely charged polyelectrolytes. This phase separation, which is triggered by environmental conditions such as the ionic strength of the surrounding environment, allows the material to undergo a transition from fluid-like to a foamy porous solid. The successive curing phase, triggered by enzymes, provides hardening of the material and therefore enhanced cohesion [6]. The widespread studies of natural systems have given new inspiration and strategies in the design of bio-mimetic and bio-inspired wet adhesive materials. Due to the knowledge derived from the mussels and the sandcastle worm, the current research in this field can be divided in two main approaches: DOPA-based adhesives and coacervate-based adhe...

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Section: Characterization Of the Modified Surfacessupporting

confidence: 92%

Thermo-Responsive Polymer Brushes with Side Graft Chains: Relationship Between Molecular Architecture and Underwater Adherence

Sidoli

Tee

Raguzin

et al. 2019

IJMS

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“…31 The in situ cell was equipped with a Peltier element, PID-temperature-controlled via a Pt1000 temperature sensor with a stability of 60.05 C (PS01, OsTech GmbH i. G., Germany). After equilibration at the respective temperatures, the POx brushes were measured in incremental steps between 20 C and 45 C. Second-derivative analysis of referenced in situ tan W spectra was done after smoothing the spectra using cubic splines to preserve the correct band positions.…”

Section: B Brush Preparationmentioning

confidence: 99%

“…14 The thermoresponsive behavior of POx and PNIPAAm involves changes in polymer-polymer and polymer-water interactions around the polymers' lower critical solution temperatures (LCST). PNIPAAm has an LCST around 31 C, 15 but also POx with a propyl group in their side chain have LCSTs in the physiological temperature range 15 and are therefore promising candidates for the use as surfaces in tissue engineering and other biomedical applications.…”

Section: Introductionmentioning

confidence: 99%

“…This is in contrast to the steplike phase transition of poly(2-oxazoline)s in solution, 24,37 and also to PNIPAAm, which shows a steplike transition around the LCST both in solution 6 and in the form of brushes. 7,31 For PcPrOx in D 2 O, two hydrated carbonylstretching components are measured at 1618-1628 cm À1 and 1600 cm À1 . While the strongly hydrated component at 1600 cm À1 clearly decreases with increasing temperature, the other component increases and seems to shift from 1618 cm À1 at 20 C to 1628 cm À1 at 45 C. A possible explanation for this shift is a gradual change from a state of hydrogen bonding with water molecules bound to other water molecules to a state of hydrogen bonding with water molecules forming a bridge between two C¼O groups.…”

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confidence: 99%

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Probing carbonyl–water hydrogen-bond interactions in thin polyoxazoline brushes

et al. 2016

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Temperature-responsive oxazoline-based polymer brushes have gained increased attention as biocompatible surfaces. In aqueous environment, they can be tuned between hydrophilic and hydrophobic behavior triggered by a temperature stimulus. This transition is connected with changes in molecule–solvent interactions and results in a switching of the brushes between swollen and collapsed states. This work studies the temperature-dependent interactions between poly(2-oxazoline) brushes and water. In detail, thermoresponsive poly(2-cyclopropyl-2-oxazoline), nonresponsive hydrophilic poly(2-methyl-2-oxazoline), as well as a copolymer of the two were investigated with in situ infrared ellipsometry. Focus was put on interactions of the brushes' carbonyl groups with water molecules. Different polymer–water interactions could be observed and assigned to hydrogen bonding between C=O groups and water molecules. The switching behavior of the brushes in the range of 20–45 °C was identified by frequency shifts and intensity changes of the amide I band.

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“…This field is fast growing, and has been extensively developed at BESSY-II (HZB Berlin) using synchrotron radiation [ 51 , 52 ], particularly driven by the interest in the characterisation of functional polymer materials and biosensors in working or sensing environments. Several interesting studies have been reported using synchrotron IRSE on smart functional polymer materials, such as the pH-dependant [ 53,54,55 ] or temperature dependant [ 56 ] swelling behaviour of polyelectrolyte brushes, and more recently the extension of these studies to protein absorption and repulsion properties of nanometre-thin stimuli-responsive smart polymer brushes [ 57 ]. The experimental arrangement for this type of studies is presented in Figures 9b and c.…”

Section: Anisotropic Materialsmentioning

confidence: 99%

Opportunities and challenges for polymer science using synchrotron-based infrared spectroscopy

Ellis

Martin

2016

European Polymer Journal

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Many breakthrough advances that are often at the cutting edge of technological development take place at synchrotron facilities. In the case of IR spectroscopy, the last decade has seen important developments in infrared instrumentation incorporated to and developed at synchrotron facilities to take advantages of the characteristics of the bright synchrotron source. In this feature article we describe the origin and nature of synchrotron infrared microspectroscopy, highlighting some of the key developments that will make a future impact in the study of macromolecular materials, and illustrating several applications in the area of polymer science.

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In-situ characterization of the temperature-sensitive swelling behavior of poly(N-isopropylacrylamide) brushes by infrared and visible ellipsometry

Cited by 18 publications

References 26 publications

Thermo-Responsive Polymer Brushes with Side Graft Chains: Relationship Between Molecular Architecture and Underwater Adherence

Thermo-Responsive Polymer Brushes with Side Graft Chains: Relationship Between Molecular Architecture and Underwater Adherence

Probing carbonyl–water hydrogen-bond interactions in thin polyoxazoline brushes

Opportunities and challenges for polymer science using synchrotron-based infrared spectroscopy

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