Evidence that three-regime kinetics is inherent to formation of a polymer brush by a grafting-to approach

Xue, Sha; Xu, Xiaohe; Sohlberg, Karl; Loll, Patrick J.; Penn, Lynn S.

doi:10.1039/c4ra05663a

Cited by 9 publications

(21 citation statements)

References 23 publications

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“…The plot of λ LSPR as a function of log(time) confirms the three-regime kinetics for PEG brush formation on 2D Ag nanoparticles (Figure 3c), which is similar to the polymer brush formation on macroscopic surfaces in the previous reports. [3][4][5]45,63 To evaluate the change in polymer brush grafting rate in the three regimes, the linear-log plot of λ LSPR versus time was fitted by straight lines to show the rate in each regime (Figure 3c, inset). The slope decreased from regime I to regime II.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Liu et al for the first time used quartz crystal microbalance with dissipation (QCM-D) to reveal the three-regime kinetics in real time, 45 which was later confirmed by Penn and co-workers. 5 QCM-D, which measures the changes in vibrational frequency as a function of mass, can analyze the total weight of polymer molecules on a surface. However, it cannot measure the density of polymer molecules or the polymer volume fraction near the surface, not to mention the complicated operational procedure that hinders precise evaluation of the kinetics.…”

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confidence: 99%

“…Despite the significant advancement of preparing polymer brushes for a wide range of applications, a fundamental understanding of the polymer brush formation mechanism has been stagnant over the past decades due to lack of appropriate analytical methods to investigate the brush formation in situ . − Since the first reports by Alexander and de Gennes, polymer brushes have been applied to a multitude of areas including surface patterning, − responsive materials design, − sensing, anticorrosion, antifouling, , polymer/nanoparticle self/directed-assembly, − stabilization, , lubrication, ,− compatibilization of polymer composites, − and modification of biological interfaces. − Polymer brushes are densely tethered polymer chains with one end attached to a surface. , To design polymer brushes effectively, it is crucial to understand the mechanism of polymer brush formation on surfaces. In the “ graft-to ” process, polymer chains first adsorb onto a surface and have a mushroom or pancake-like shape.…”

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confidence: 99%

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Two-Dimensional Plasmonic Nanoparticle as a Nanoscale Sensor to Probe Polymer Brush Formation

et al. 2017

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Conventional analysis and characterization of polymer brush formation relies on laborious methods that use a quartz crystal microbalance, atomic force microscope, microcantilever, or other tools that measure the concentration change of solutions. Herein we develop a simple and easy method that utilizes intrinsically flat two-dimensional (2D) plasmonic nanoparticles as sensors for unveiling the mechanism of polymer brush formation on surfaces. Via ultraviolet-visible spectroscopy, the plasmonic nanoparticles can be used to determine the amount of polymers near the surface in situ. As the amount of polymers increases near the surface, the nanoparticle characteristic localized surface plasmon resonance wavelength redshifts, and the shift amount corresponds linearly to the polymer density near the surface. By functionalizing the nanoparticles in solutions of thiolated polyethylene glycol (PEG-SH) with or without PEG disulfide (PEG-S-S-PEG), the three-regime kinetics of the polymer brush formation is confirmed. The fast adsorption and slow chain rearrangement in the first regime are found to be the causes of the latent regime. In the latent regime, the adsorbed polymer chains rearrange to anchor their ends onto the surface and contract to liberate space so that other polymer chains can graft onto the surface until saturation. The fundamental understanding gained herein enables the design of surfaces with complex chemistries and properties, which can find broad applications in responsive sensors, films, and coatings. Moreover, the novel analytical method of using 2D plasmonic nanoparticle as a sensor to understand the polymer brush formation is applicable to investigating the grafting of other molecules such as self-assembled monolayers, protein, and DNA.

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Section: ■ Results and Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Two-Dimensional Plasmonic Nanoparticle as a Nanoscale Sensor to Probe Polymer Brush Formation

et al. 2017

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“…As grafting is expected to occur gradually with the continuous progress of the peroxide decomposition and subsequent coupling of chitosan, the surface effects observed by contact angle measurements are expected to appear similarly, in a monotonous way, likely with some saturation and levelling-off for the wettability by water [45]. We actually observe an inversion point, suggesting the occurrence of a more complex process.…”

Section: Chitosan Grafting Reactionmentioning

confidence: 66%

Electron-Beam-Induced Grafting of Chitosan onto HDPE/ATZ Composites for Biomedical Applications

Faga¹,

Duraccio²,

Maro³

et al. 2021

Polymers

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The surface functionalisation of high-density polyethylene (HDPE) and HDPE/alumina-toughened zirconia (ATZ) surfaces with chitosan via electron-beam (EB) irradiation technique was exploited for preparing materials suitable for biomedical purposes. ATR–FTIR analysis and wettability measurements were employed for monitoring the surface changes after both irradiation and chitosan grafting reaction. Interestingly, the presence of ATZ loadings beyond 2 wt% influenced both the EB irradiation process and the chitosan functionalisation reaction, decreasing the oxidation of the surface and the chitosan grafting. The EB irradiation induced an increase in Young’s modulus and a decrease in the elongation at the break of all analysed systems, whereas the tensile strength was not affected in a relevant way. Biological assays indicated that electrostatic interactions between the negative charges of the surface of cell membranes and the –NH3+ sites on chitosan chains promoted cell adhesion, while some oxidised species produced during the irradiation process are thought to cause a detrimental effect on the cell viability.

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“…49 Meticulous investigations regarding polymer grafting kinetics by Penn and coworkers for different polymer systems encountered a third regime where thermal fluctuations create openings large enough to accommodate new coils, and a mushroom to brush conformational change occurs. 19,[50][51][52][53][54][55][56][57][58] In the present work, we demonstrate how the grafting density of the PEG brush layer can be systematically tuned by the addition of a salt (Na2SO4) with a strong salting-out effect. The thiolated polymers are directly attached to gold, which is a widely used material in bio-interface science.…”

Section: Introductionmentioning

confidence: 71%

Salt-Induced Control of the Grafting Density in Poly(ethylene glycol) Brush Layers by a Grafting-to Approach

Ortiz

Olsen²,

Thormann

2018

Langmuir

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In this work, a method to obtain control of the grafting density during the formation of polymer brush layers by the grafting-to method of thiolated poly(ethylene glycol) onto gold is presented. The grafting density of the polymer chains was adjusted by adding NaSO in concentrations between 0.2 and 0.9 M to the aqueous polymer solution during the grafting process. The obtained grafting densities ranged from 0.26 to 1.60 chains nm, as determined by surface plasmon resonance. The kinetics of the grafting process were studied in situ by a quartz crystal microbalance with dissipation, and a mushroom to brush conformational transition was observed when the polymer was grafted in the presence of NaSO. The transition from mushroom to brush was only observed for long periods of grafting, highlighting the importance of time to obtain high grafting densities. Finally, the prepared brush layer with the highest grafting density showed high resistance to the adsorption of bovine serum albumin, while layers with a lower grafting density showed only limited resistance.

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Evidence that three-regime kinetics is inherent to formation of a polymer brush by a grafting-to approach

Abstract: Display of three-regime kinetics requires sufficiently low temperature and concentration: too high (left) vs. low enough (right).

Cited by 9 publications

References 23 publications

Two-Dimensional Plasmonic Nanoparticle as a Nanoscale Sensor to Probe Polymer Brush Formation

Two-Dimensional Plasmonic Nanoparticle as a Nanoscale Sensor to Probe Polymer Brush Formation

Electron-Beam-Induced Grafting of Chitosan onto HDPE/ATZ Composites for Biomedical Applications

Salt-Induced Control of the Grafting Density in Poly(ethylene glycol) Brush Layers by a Grafting-to Approach

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