Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



TECH SPACE
Self-assembly of photoresponsive polymer brushes to realize advanced surfaces
by Staff Writers
Nagoya, Japan (SPX) Oct 31, 2016


Schematic depiction of polymer brush formation through the surface segregation and lateral self-assembly of a block copolymer consisting of a liquid crystalline polymer (LCP) connected with polystyrene on a polystyrene base film. The photo displays a transmission electron microscopic (TEM) image showing the extended polymer brush layer formed on the air side of a polystyrene film. Image courtesy Koji Mukai and Takahiro Seki. For a larger version of this image please go here.

Polymer surface coatings are important in numerous applications for producing surfaces with desired properties such as wettability, low friction, and biocompatibility. Surfaces are usually modified with polymers through grafting approaches to form chemical bonds between the surface and polymer.

The type of grafting approach can influence the ordering and, consequently, the properties of the polymer coating. For example, polymer brushes are polymers tethered vertically with respect to the underlying surface, and can display quite different properties to the equivalent polymer with random orientation. Polymer brushes are typically formed by polymerization initiated at surfaces.

A team of Nagoya University researchers have developed a new strategy to obtain polymer brushes on surfaces using diblock copolymers consisting of two types of units that form segregated structures.

"The formation of polymer brushes was driven by the ability of our copolymers to segregate and self-assemble on a base polymer surface when heated appropriately," corresponding author Shusaku Nagano says.

The group first synthesized diblock copolymers containing polystyrene (PS) and poly(azobenzene) (PAz)-based units. The PS and PAz units possessed different properties such as surface energy and flexibility.

This caused the copolymers to segregate into their different blocks on PS substrate surfaces when annealed at a temperature higher than the glass transition temperature of PS. The segregation was confirmed by contact angle measurements, transmission electron microscopy, and X-ray photoelectron spectroscopy.

The researchers found that the PAz units formed a "skin" on the PS surface. The thickness of the PAz skin layer depended on the ratio of the two types of polymer units in the copolymer. In the skin layer, the main chain of PAz was highly extended to form a polymer brush structure, which was attributed to the presence of the bulky azobenzene units of PAz.

Ultraviolet-visible absorption measurements indicated that a PS substrate prevented aggregation of the diblock copolymer during annealing. The main chains of PAz were oriented horizontally in a film of the copolymer alone. In contrast, an underlying PS surface caused the main chains of PAz to orient vertically with respect to the surface.

This is because the PS units of the diblock copolymer interacted with the underlying PS layer, resulting in formation of a surface layer of vertically oriented PAz units organized as densely packed polymer brushes. Formation of this structure was driven more by the lower surface tension of the PAz units than the PS ones, and the ability of the PAz units to self-assemble.

The approach's advantages include easy controllability of brush thickness and structure by changing the number and/or type of units in the diblock copolymer and the ability to form polymer brushes on flexible substrates.

"These organized polymer surfaces are stable in air and should be resistant to damage," lead author Koji Mukai explains. "A damaged surface should be able to self-heal simply by annealing because of the lateral mobility of the polystyrene anchoring units."

Additionally, the photosensitive azobenzene units of the PAz brushes could be further aligned by exposure to light irradiation. This strategy can likely be extended to obtain functional surface coatings using the segregation and self-assembly of diblock copolymers to other polymer systems.

The article, "High-Density Liquid-Crystalline Polymer Brushes Formed by Surface Segregation and Self-Assembly" was published in Angewandte Chemie International Edition at DOI: 10.1002/anie.201607786


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Nagoya University
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
TECH SPACE
How water flows near the superhydrophobic surface
Moscow, Russia (SPX) Oct 24, 2016
Water (and other liquids) has an unusual property when it flows closely to some specially designed surfaces: its speed isn't equal to zero even in the layer that directly touches the wall. This means that liquid doesn't adhere to the surface, but instead slides along it. Such an effect is called hydrodynamic slip and it was first described more than 200 years ago. However, at that time it hasn't ... read more


TECH SPACE
Urine may be the X factor to exploring deep space

The Space Cadets of 2016

NASA Shakes Up Orion Test Article for the Journey to Mars

Beaches, skiing and tai chi: Club Med, Chinese style

TECH SPACE
Boosting Europe's all-electric satellites

Guiding Supply Ship to the International Space Station

The Pressure is On for SLS Hardware in Upcoming Test

First launch for Orbital's Antares rocket since '14 blast

TECH SPACE
Did it crash or land? Search on for Europe's Mars craft

Rover Conducting Science Investigations at 'Spirit Mount'

MAVEN mission observes ups and downs of water escape from Mars

A graveyard of broken dreams and landers

TECH SPACE
China to enhance space capabilities with launch of Shenzhou-11

Ambitious space satellite projects set for liftoff

China's permanent station plans ride on mission

China to enhance space capabilities with launch of Shenzhou-11

TECH SPACE
Airbus DS contracts with Intelsat General for European Defence Communications

Final exams prepare Thomas Pesquet for launch

Airbus DS in partnership with Orbital ATK to build EUTELSAT 5 West B

Third party satellite launch order bookings for Isro stands at $42 million

TECH SPACE
Using Photonics to Call Home

Researchers use temperature to control droplet movement

Self-assembly of photoresponsive polymer brushes to realize advanced surfaces

Liquid-repellant tape adheres to any surface

TECH SPACE
Tatooine worlds orbiting 2 suns often survive violent escapades of aging stars

Oldest known planet-forming disk found

ALMA spots possible formation site of icy giant planet

Astronomers find oldest known planetary disk

TECH SPACE
Uranus may have two undiscovered moons

Possible Clouds on Pluto, Next Target is Reddish

Curious tilt of the Sun traced to undiscovered planet

Shedding light on Pluto's glaciers




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement