Free Newsletter
Register for our Free Newsletters
Newsletter
Zones
Advanced Composites
LeftNav
Aerospace
LeftNav
Amorphous Metal Structures
LeftNav
Analysis and Simulation
LeftNav
Asbestos and Substitutes
LeftNav
Associations, Research Organisations and Universities
LeftNav
Automation Equipment
LeftNav
Automotive
LeftNav
Biomaterials
LeftNav
Building Materials
LeftNav
Bulk Handling and Storage
LeftNav
CFCs and Substitutes
LeftNav
Company
LeftNav
Components
LeftNav
Consultancy
LeftNav
View All
Other Carouselweb publications
Carousel Web
Defense File
New Materials
Pro Health Zone
Pro Manufacturing Zone
Pro Security Zone
Web Lec
Pro Engineering Zone
 
 
 
News

Hierarchical porous polymer film synthesis controls pore sizes

Cornell University : 12 August, 2013  (Special Report)
Forming perfect porous polymer films is not enough; they need both large and small pores, and the process of making them needs to be simple, versatile and repeatable. Creatively combining already established techniques, Cornell materials researchers have devised a so-called hierarchical porous polymer film synthesis method that may help make these materials useful for applications ranging from catalysis to bioengineering.

The hierarchically structured polymers are porous at both micron- and nano-length scales. This provides both high flux, which means materials can flow through it efficiently, as well as high surface area – both important, for example, in rapid catalytic conversions. The materials were self-assembled from a series of block copolymers, which are large molecules comprising "blocks" of repeating units.

Researchers have made such porous materials before, according to Ulrich Wiesner, the Spencer T Olin Professor of Engineering, but the methods usually involve post-processing; for example, once the polymer is made, the pores need to be etched into the material.
With their new method, the researchers achieved dual porosity by evaporating a solvent from a mixture of a block copolymer with a small molecule additive that is chemically similar to one of the blocks. The two components form two coexisting phases, like water and oil, with a continuous interface between them separated by tens of microns. This method of phase separation is known as spinodal decomposition.

One of the two phases rich in the block copolymer then phase-separates on the tens of nanometers scale into two domains formed by the two blocks of the copolymer. One of the blocks, a polyethylene oxide (PEO) block, is swollen with the small molecule additive, which is immiscible – doesn't mix – with the other block of the polymer. When the additive is washed away, what remains is a continuous pattern of porosities on two lengths scales – tens of microns, and tens of nanometers.

The researchers tried the method with multiple diblock and even triblock polymers, and contend that the method can be generalised for making many versions of this material. They were also able to easily tune the nanostructure of the resulting polymer by adjusting the temperature at which the original organic solvent was evaporated.

Electron microscopy confirmed that the calcite infiltrated the entire structure, small and large pores, thus demonstrating transport of calcite precursors through the porous structure.

Bookmark and Share
 
Home I Editor's Blog I News by Zone I News by Date I News by Category I Special Reports I Directory I Events I Advertise I Submit Your News I About Us I Guides
 
   © 2012 NewMaterials.com
Netgains Logo