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Monday, September 17, 2007

MATERIAL CHEMISTRY DEFINED

An important step forward, to define Materials Chemistry, was taken by The Royal Society for Chemistry (RSC) at the Sept 12, 2006, workshop. The workshop brought together almost 50 delegates, leading experts in the field and published online 5 pre-workshop presentations, free to download making a valuable ebook on the subject. The practising experts, renowned Chemists, Materials Scientists, Technologists and Engineers confronted with the problems arising within the materials and chemical sciences, technologies and engineering drew up key questions and attempted to provide adequate answers.

The rational and the thought processes which arose during the meeting are in themselves highly instructive and educational.

-Questions such as why focus on Materials Chemistry?
-What distinguishes Materials Chemistry from simple chemical substances?
-Define materials chemistry in a few words
and give some examples of areas of research that should be included.
-Should there be a distinction between functional and structural materials in the definition?
-Does materials chemistry cover both?
-What is the difference between materials chemistry and materials science?
-What isn’t materials chemistry?
-What should not be included in the definition.


Unfortunately the "ebook" is nolonger available online via the RSC site as far as I can tell. I do not believe this is e-mateial is highly sensitive!

The RSC Workshop ebook may be downloaded at the following links, nolonger:

Why focus on Materials Chemistry?
Within the broad family of chemical sciences, it transpires that an increasingly high percentage of publications are classified as Materials Chemistry (cf. Leonard V. Interrante's presentation, Link in Pdf format)
laying claim to the stature of a distinct discipline, in practice involving multi-disciplinary or interdisciplinary skills.

The need for a definition.

The inherent complexity involved makes the task of defining the subject equally complex and therefore even more necessary in order to express the ideas, concepts and science involved as succinctly as possible, to further the recognition of the discipline in itself and so provide assistance to publishers and funding agencies.

In the words of Peter Day who asks rhetorically,

“Why bother about definitions? “
And gives the following reply
“- For clarity: a new cross-cutting discipline
-To give materials chemistry a place in the International Union of Pure and Applied Chemistry (IUPAC) "
Cf. P. Day’s presentation, Link in Pdf format



NB. IUPAC Link Compendium of Chemical Terminology




Material Chemistry Defined?

To date the discipline has developed organically and to a large extent, the common idea of what constitutes materials chemistry is circularly linked to the type of work done by “materials chemists”.

Typical areas in which materials chemist work are as follows:
-application can be a prime element in motivation
-Areas of application cover:
-structural or functional
-designing and processing materials
-Characterisation and analysis

What is a Material?

It emerged that “The Key to progress in the defining of materials chemistry was to define what constitutes a material in contrast to just a chemical.

In the words of Paul O’Brien

‘So when does chemistry become materials chemistry?
Materials chemistry must, pedantically, have something to do with a material as
opposed to a chemical.’

O’Brian goes on to illustrate this by quoting from the eminent Metallurgist Robert W. Cahn’s book ‘The Coming of Materials Science’, (p253) Ed. Pergammon, Oxford, 2001.

“The key to understanding the formation of p and n type semiconducting material came from careful work in which metallurgists correlated properties with traces of dopants. One of the key features of the properties of semiconductors is that conventionally chemically and crystallographically identical samples can have different properties because of traces of group 3 or 5 dopants." R. W. Cahn.

The dictionary defines a material as “a physical substance from which things can be made from”, quite unsuitable for the aims of such a workshop whose members represent the material chemistry community, whose practise today involves long years of study and practice, whose responsibility involves publishing, peer reviewing, advising on and facilitating access to funding, defining the fields within the International Union of Pure & Applied Chemistry. A more technical and profound definition was obviously called for.

Should there be a distinction between functional and structural materials in our definition?

The experts considered the following

Concepts Essential to Define Materials “chemistry”

-Structure & properties
-Functionality
-Application
-Design ( refers to design at the atomic or molecular level)


For example:
A material has properties which give it a particular useful application,
either
structural, as with a building material,
or
functional, as with materials used to make devices.
(Electronic, optical or magnetic)

Duncan W. Bruce gave examples of liquid crystal materials chemistry including markets, basic molecular structures and the functions for which these materials are used. Link_Pdf format


Properties

A material is generally thought of as an organised phase where interactions between particles play a large role, although clearly there are cases where amorphous phases are also crucial..

Material versus Chemical Substance
The properties of a material emerge from the way these sub-units are put together:
-Whilst a single molecule will have properties related to its chemical
structure which remain constant, the properties of a material are dependent on how its sub-units are assembled.

Properties can, and as in Metallurgy, often, arise from structural defects (materials made of the same chemical sub-units can have different properties e.g. the properties of polymers for example depend on their supramolecular and meso/morphological structure.

The relationship between structure and property could be used to define a material and differentiate it from a chemical.

Compare for example:
-a material would be a nano-tube, whose properties will vary depending on its structure.
whereas
-a molecule of benzoic acid, which is a chemical whose properties are related only to its chemical make-up.

The difference between materials science and materials chemistry

There are areas of contention when trying to define the sub-discipline materials chemistry.

Would catalysis be considered part of the field?

Homogeneous catalysis would certainly not fit the definition but would heterogeneous catalysis? The synthesis of certain types of novel catalyst materials could fit parameters by which materials chemistry has been described.

Materials chemistry does share some (many?) common elements with Materials Science with perhaps differences in scale?

But often the scale of elements studied differ, with materials chemistry being concerned with a molecular understanding of materials, whilst materials science looking at a larger scale.

Materials chemistry can be concerned with properties up to the micron scale.

It must be recognised that there is a big overlap and many materials scientists will be working to the same end as many materials chemists. Materials chemistry certainly requires an understanding of the principles of both chemistry and materials science and sometimes physics and biology.

The interdisciplinary nature of the work is an important element that may differentiate materials chemistry from general chemistry but strengthens its relationship with material science.

What isn’t materials chemistry:

Synthesising any material was not materials chemistry but
just chemical synthesis. Synthesis is a major part of what chemists do.

The sub-discipline materials chemistry must include an element of
application, function or novel design that is beyond the simple chemical reactivity of
the species in question.

Design:

Design refers to design at the atomic or molecular level, design at a greater length scale becomes Materials Science and Engineering. Work on novel materials that may show potential applications must be included as materials chemistry as chemists may generate new types of materials with previously unknown properties leading to unimagined applications


Conceptual maps [Link TBD]

The following conceptual map outlines are
-Chemistry subject map
-Materials chemistry subject map
Link



Some working definitions of materials chemistry

“Chemistry related to the preparation, processing and analysis of materials”*

• Preparation: The synthesis of new materials; development of improved routes to known materials
• Processing: modifying materials to enhance their utility (e.g., dying, coating, nanoparticle
generation, etc. )
• Analysis: everything from characterization of structure at multiple length scales to the
theoretical interpretation of behaviour
*L.V. Interrante, “Materials Chem, a New Sub-discipline”, MRS Bulletin, Jan., 1992, p. 4.

Chemistry of Advanced Materials - Ch 1: Introductory Terms and Concepts
The definition of materials as “substances having properties which
make them useful in machinery, structures, devices and products*”, connects materials with function and through that function, utility
*M. Cohen, Ed., Mats. Sci. & Eng.: Its Evolution, Practice and Prospects; Mater. Sci. Eng. 37(1) (1974); M.B. Bever, Encyclopedia of Mats. Sci. & Eng., Vol. 1,(1986)


Selected Results from a Google Search for Materials Chemistry

• Univ. Wisconsin Chemistry website
– Materials Chemistry can be defined as the branch of chemistry aimed at the preparation,
characterization, and understanding of substances/systems that have some specific useful function (or potentially useful function)
• Washington Univ. Chemistry website
– Materials chemistry involves the synthesis and study of materials that have interesting and potentially useful electronic, magnetic, optical, and mechanical
properties
• Univ. of Oregon Chemistry website
– Materials chemistry is a relatively new discipline centered on the rational synthesis of novel functional materials using a large array of existing and new synthetic methods

Summary of working definition of materials chemistry as suggested at the workshop.

Materials Chemistry is:


- the chemistry of the design, synthesis and characterisation of assemblies of molecules whose properties arise from interactions between them.

- is the understanding, synthesis, processing and exploitation of compounds or substances in their assembled form.

- is the synthesis, processing, characterisation, understanding and exploitation of compounds that have useful or potentially useful properties and applications.





The RSC Workshop ebook may be downloaded at the following links:

THESE LINKS ARE NOLONGER AVAILABLE VIA RSC SITE -My Apologies.



Material Chemistry Maps (Paul O’Brian)Link Pdf format

Why bother about definitions? (Peter Day)Link Pdf format

Liquid Crystals by Duncan W.Bruce, Link Pdf format

IUPAC's role by Tony West, Link Pdf format

Statistics, References to Materials Chemistry... by Leonard V. Interrante, Link Pdf format




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