Tribological Behavior of Ionic Polymer Brushes in Aqueous Environment

ABSTRACTFor biological and mechanical systems involving moving parts, surface slipperiness is often a critical attribute for their optimal functions. Surface grafting with hydrophilic polymers is a powerful means to render materials slippery in aqueous environment. In “inverted grafting-to approach”, the hydrophilic polymer chains of amphiphilic diblock copolymers dispersed within a poly(dimethylsiloxane) (PDMS) network are selectively segregated upon exposure to aqueous solution. This allows formation of extremely stable brush-like polymer layers. Tribological application of inverted grafting-to approach was successfully demonstrated with PDMS-block-poly(acrylic acid) (PDMS-b-PAA) dispersed within thin PDMS films on PDMS blocks by showing friction coefficients (µ) of ca 10-2 to 10-3, depending on the load, pH and buffer salinity in the absence of other external re-supply of PAA chains. Further manipulations of the thin PDMS film incorporating PDMS-b-PAA to optimize the tribological properties are presented. Lastly, first trials to employ PAA-grafted PDMS surface to generate in-vitro mucosae model are also presented and discussed.

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Chemical Design of Non‐Ionic Polymer Brushes as Biointerfaces: Poly(2‐oxazine)s Outperform Both Poly(2‐oxazoline)s and PEG

Angewandte Chemie International Edition ◽

10.1002/anie.201805620 ◽

2018 ◽

Vol 57 (36) ◽

pp. 11667-11672 ◽

Cited By ~ 49

Author(s):

Giulia Morgese ◽

Bart Verbraeken ◽

Shivaprakash N. Ramakrishna ◽

Yvonne Gombert ◽

Emma Cavalli ◽

...

Keyword(s):

Polymer Brushes ◽

Ionic Polymer ◽

Chemical Design

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Fluid Flow in the Vicinity of a Vibrating Ionic Polymer Metal Composite: Part 1—Experimental Study

ASME 2009 Dynamic Systems and Control Conference, Volume 1 ◽

10.1115/dscc2009-2587 ◽

2009 ◽

Author(s):

Sean D. Peterson ◽

Maurizio Porfiri ◽

Alessandro Rovardi

Keyword(s):

Flow Field ◽

Aqueous Environment ◽

Metal Composite ◽

Propulsion Systems ◽

Ionic Polymer ◽

Physical Experiments ◽

Underwater Propulsion ◽

Polymer Metal ◽

The Mean ◽

High Flexibility

Low power consumption and activation voltage combined with high flexibility and minimal weight make Ionic Polymer Metal Composites (IPMCs) well-suited for miniaturized underwater propulsion systems. In this series of papers, we comprehensively discuss the flow field induced by an IPMC strip vibrating in a quiescent aqueous environment by performing complementary physical experiments and numerical simulations. The experimental results are presented in this paper. Planar particle image velocimetry is used to measure the time-averaged flow field of a vibrating IPMC. The momentum transferred to the fluid is computed to estimate the mean thrust generated by the vibrating actuator. We find that the mean thrust increases with the Reynolds number, defined by the maximum tip speed and IPMC length, and is only marginally affected by the relative vibration amplitude. Detailed understanding of the flow environment induced by a vibrating IPMC can guide the optimization of IPMC-based propulsion systems for bio-mimetic robotic swimmers.

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A Twistable Ionic Polymer-Metal Composite Artificial Muscle for Marine Applications

Marine Technology Society Journal ◽

10.4031/mtsj.45.4.9 ◽

2011 ◽

Vol 45 (4) ◽

pp. 83-98 ◽

Cited By ~ 29

Author(s):

Kwang J. Kim ◽

David Pugal ◽

Kam K. Leang

Keyword(s):

Degrees Of Freedom ◽

Large Strain ◽

Aqueous Environment ◽

Driving Voltage ◽

Metal Composite ◽

Ionic Polymer Metal Composite ◽

External Stimulation ◽

Ionic Polymer ◽

Electromechanical Transduction ◽

Polymer Metal

AbstractIonic polymer-metal composite (IPMC) artificial muscles (AMs), due to their low driving voltage (<5 V), large strain, soft and flexible structure, and ability to operate in an aqueous environment, are suited for creating artificial fish-like propulsors that can mimic the undulatory, flapping, and complex motions of fish fins. Herein, a newly developed IPMC AM fin with patterned electrodes is introduced for realizing multiple degrees-of-freedom motion, such as bending and twisting. Also, by carefully creating isolated patterns of electrodes on the surface of the polymer-metal composite, sections of the composite can function as an actuator, while other areas can be used for sensing fin deformation and responses to external stimulation. The manufacturing, modeling, and characterization of a twistable AM fin are discussed. The sectored electrode pattern on the AM fin is created using two techniques: masking and surface machining. Using first principles, detailed models are developed to describe the electromechanical transduction for the IPMC AM fin. These models can be used to guide the development of more complex AM fin geometries and electrode patterns. The bending and twisting performance of a prototype twistable AM fin is evaluated and compared to the models. Experimental results demonstrate good twisting response for a prototype fin. Technical design challenges and performance limitations are also discussed.

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Addressing skin abrasions on artificial turfs with zwitterionic polymer brushes

RSC Advances ◽

10.1039/c5ra26194e ◽

2016 ◽

Vol 6 (39) ◽

pp. 32446-32453 ◽

Cited By ~ 1

Author(s):

S. P. Tay ◽

P. Fleming ◽

S. Forrester ◽

X. Hu

Keyword(s):

Polymer Brushes ◽

Aqueous Environment ◽

Zwitterionic Polymer ◽

The Common

Zwitterionic polymer brushes were investigated for their skin-friendliness outside of the common aqueous environment, exhibiting superior lubrication and antifouling properties.

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Surface functionalization by smart binary polymer brushes to tune physico-chemical characteristics at biointerfaces

e-Polymers ◽

10.1515/epoly.2005.5.1.794 ◽

2005 ◽

Vol 5 (1) ◽

Author(s):

Petra Uhlmann ◽

Nikolay Houbenov ◽

Sergiy Minko ◽

Manfred Stamm

Keyword(s):

Polymer Brushes ◽

Structural Changes ◽

Surface Engineering ◽

Surface Characteristics ◽

Polymer Chains ◽

Aqueous Environment ◽

Binary Polymer ◽

Physico Chemical ◽

Versatile Tool ◽

Model Protein

AbstractPolymer brushes consist of an assembly of polymer chains that are attached by one end to the surface with sufficient grafting density. Binary brushes constituted from two incompatible polymers can be used in the form of ultrathin polymeric layers as a versatile tool for surface engineering to tune physicochemical surface characteristics as wettability, surface charge, chemical composition or morphology, and furthermore to create responsive surface properties. It is also possible to fix surface structures obtained in this way by (photo)crosslinking of the layers. Mixed brushes of oppositely charged polyelectrolytes are representing a special case of responding surfaces, which are sensitive to changes of the pH in aqueous environment. It is shown that structural changes occur in the plateau region of the adsorption isotherm of a model protein and that changes of the pH also cause changes in the structure of the adsorbed protein layer.

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