Model clays and the importance of good networking

Model clays and the importance of good networking

The ability to predict mesoscale structure based on the various attributes of nanoparticles, particularly particle size, size distribution, aspect ratio, and chemical functionality, is necessary to understand and potentially tailor the physical response of multi-functional materials.  Recently, molecular-scale modeling approaches have indicated that simple estimates of particle shape and local order in a fluid are sufficient to predict various categories of structural order for many convex polyhedral [Damasceno Science 2012; 337 (6093):453-7].  However, these discontinuous nano-scale modeling approaches implicitly assume local constitutive relationships that may introduce considerable error if interfacial interactions or non-local coupling between mechanical fields are present.  Extensive experimental investigations have been attempted, but little detail on the fundamental physics of the nanoparticles is possible because of challenges in achieving reproducible properties of an ensemble of individual nanoparticles.

Nanoparticles 101 - Quantum Dots

Nanoparticles 101 - Quantum Dots

The ability to predict mesoscale structure based on the various attributes of nanoparticles, particularly particle size, size distribution, aspect ratio, and chemical functionality, is necessary to understand and potentially tailor the physical response of multi-functional materials.  Recently, molecular-scale modeling approaches have indicated that simple estimates of particle shape and local order in a fluid are sufficient to predict various categories of structural order for many convex polyhedral [Damasceno Science 2012; 337 (6093):453-7].  However, these discontinuous nano-scale modeling approaches implicitly assume local constitutive relationships that may introduce considerable error if interfacial interactions or non-local coupling between mechanical fields are present.  Extensive experimental investigations have been attempted, but little detail on the fundamental physics of the nanoparticles is possible because of challenges in achieving reproducible properties of an ensemble of individual nanoparticles.

How Conventional Adhesives Work

How Conventional Adhesives Work

All adhesives in widespread use today can be considered “wet” adhesives.  These materials are typically applied to a surface in a liquid state and achieve intimate contact by flowing along the surface and wetting surface asperities.  To be an effective adhesive, the liquid must be transformed into a solid with high cohesive strength through either a chemical reaction (crosslinking), or in the case of hot melts, by cooling below the melting temperature.

Electrospinning: Historical Context

Electrospinning: Historical Context

Dry adhesion has been a topic of significant academic and industrial interest since the early 2000’s, and a number of different approaches have been explored to create commercial products.  Despite an immense effort and a number of extremely impressive academic reports, little progress has been made outside of laboratories due to challenges in the scalability of the approaches.  One of the major value propositions of AAI’s approach is the use of a manufacturing approach that is already well known and established: electrospinning.  Although it may not be quite a household word yet, electrospinning has a remarkable and rich history dating to pre-industrial times.

William Gilbert - 17th century physician, scientific rebel, and forefather of electrospinning

William Gilbert - 17th century physician, scientific rebel, and forefather of electrospinning

The first reports on the influence of an electrical charge on a liquid date back to the turn of the 17th century.  At the time, scientists followed the Aristotelian approach and musing about phenomena without any real urge to verify.  William Gilbert was among a new generation of natural philosophers that rejected this Aristotelian approach and instead performed experiments to test prevailing views. 

Robert Hooke - Artificial silk, cells, elasticity, astronomy, architecture, combustion, and more

Robert Hooke - Artificial silk, cells, elasticity, astronomy, architecture, combustion, and more

The concept of a synthetic fiber was first suggested by none other than Robert Hooke, another Englishman of notoriety from the 17th century.  Hooke built some of the earliest telescopes to observe the planets, and was among the first to flip the telescopes around and use them as microscopes to study plant and animal cells.  In fact, he was the one that coined the term “cell” to describe the basic unit of life.  His contribution to the story of electrospinning was in a passing reflection that if “very quick ways of drawing [a synthetic fiber] out into small wires for use could be found,” then artificial silk could be produced.

Dispersion and Organization with Carbon Nanotubes

Dispersion and Organization with Carbon Nanotubes

Part 4 of 4 of the epic nanoscale phenomena mini-series, composed during multi-hour travel delays over the holidays... Carbon nanotubes are very exciting materials that are very challenging to use because they really like to group together rather than spreading out.  This is because interactions between particles also increase with surface area, which poses a big challenge (this is also part of the reason why electrospun nanofibers can stay together without a binder when used as a dry adhesive!).  The challenge is how to separate the tubes without changing their properties too much.

Nanoscale Phenomena: Importance of the Interface

Nanoscale Phenomena: Importance of the Interface

In the field of polymer nanocomposites, there is a great deal of interest in nanoparticles because they can directly interact and influence the behavior of individual polymer chains.  The ease of mobility of a polymer chain greatly influences its bulk properties.  Generally, we are forced to change the entire structure of the polymer in order to modify something like its use temperature or mechanical properties.  Using nanoparticles, we can completely change the behavior of a conventional polymer that is easier to process or prepare that so-called "engineering plastics."

Nanoscale Phenomena: Importance of Being Small

Nanoscale Phenomena: Importance of Being Small

Nanomaterials are so finely divided that they exhibit properties that are intermediate between the macro-scale behavior we are accustomed to, and true molecular-scale behavior.  They may show unique  properties related to changes in  electrical, optical, mechanical, and thermal phenomena (some examples to follow), or may be even more exotic, such as quantum confinement, where the size of a particle is so small that we are altering the configuration and interactions of its atoms and electrons.

Nanoscale Phenomena and Applications – A Gentle Introduction

Nanoscale Phenomena and Applications – A Gentle Introduction

Nanoscale phenomena is as nice a place as any to begin a series of non-technical technical articles.  After all, it has all the trimmings of remarkable potential, fertile innovation opportunities, challenges in commercialization, and non-intuitive barriers to entry, each deserving of its own consideration.  You, me, and everything we generally think of as reality exist on the macroscale.  It’s the arena where our senses make sense, where we live our lives and where we can have some intuitive understanding of the world around us.  To put it a bit more technically, it’s the arena where things are continuous.  Included here are 3 relatively short articles on nanoscale phenomena, which will eventually wrap around to the world of nanofibers, electrospinning, and adhesion that all contribute to the nexus that is Akron Ascent.

Dry Adhesion Primer

Dry Adhesion Primer

AAI’s dry adhesive technology is based on the principle of contact splitting, which is a robust and reversible (elastic) mechanism of adhesion commonly exploited by animals such as flies, beetles, spiders, and the most prolific climber of all, the gecko.  All surfaces have some attractive force between them arising from weak, inter-molecular forces known as van der Waals (vdW) forces.  This force decreases linearly with the size of the contact, but the resulting stress (force divided by area), increases.  As a result, a surface made up on a large number of small contact sites will have an immensely larger interaction with a target surface than a smooth one.