Formulation Chemistry
David Young
Cytoclonal Pharmaceutics Inc.
Formulation chemistry is one of the disparities in the chemistry industry.
There are many jobs, but extremely few degree programs that adequately
train students for a formulation position. As a result, most formulation
chemists are either self taught or have in essence been apprenticed
under experienced researchers.
Simply put formulation is the mixing of compounds which do not react in
order to get a mixture with the desired characteristics. Examples of
formulations are adhesives, paints, inks, cosmetics, detergents and
many pharmaceutical products. This is product development work that
is very focused on the characteristics needed for a product to be
profitable.
Since no reactions are being done, there is no reason to work with gram
formula weights of compounds. Most formulations are done by measuring
liquids by volume and solids by weight. A product may go to market
without any chemical equations ever being written down.
The chemical principles involved
Even though there are no chemical reactions involved, there are many
aspects of chemistry present in a formulation. Some of the chemistry
involved is thermodynamics of mixing, phase equilibria, solutions,
surface chemistry, colloids, emulsions and suspensions. Even more important
is how these principles are connected to adhesion, weather resistance,
texture, shelf life, biodegradability, allergenic response and many
other properties.
Quite a bit has been done by a fairly trial and error method. In this
scheme, the product development chemist will have a list of substances
used to modify mixtures (i.e. thickeners). They will then go through a
trial and error process to see what concentration of which compound will
work best for a specific application. Of course, the scientists and
engineers hired to do this work recognize the value of having an
understanding of the processes involved to guide their choices of which
to try. In product design more than many other areas, new researchers
are hired with very basic knowledge and trained internally to understand
formulations. In recent years, there has been an increase in
work to develop the underlying scientific principles, and apply them
in the form of software to predict formulations. At the present time,
some parts of the field are following this approach, while other parts
of the field are still using a trial and error scheme.
Where should formulation chemistry fit in the curriculum? A lecture
discussion might fit in with either general chemistry or physical chemistry.
A laboratory experiment could be included at almost any level, but perhaps
freshman is best. Unfortunately, formulations do not make a particularly
good graduate research project. The natural collaboration and funding source
for a formulation project would be working with an industrial partner.
However, the product development stage is one at which industries are most
sensitive about keeping their knowledge safely in house. Industries tend
to work with academic partners on developing new technology but are
very hesitant to share their profitable trade secrets with academic
researchers. When collaborations are made, the industry will naturally put
strict restrictions on publishing the results (other than in a patent held
by them). Since academic researchers base their success on the number of
publications rather than on profits this is an unfavorable arrangement for
the academic researchers as well.
The following sections give an idea of the concerns addressed by formulation
chemists in a number of areas. There are many other areas in which
formulations are important. See the references for more research areas.
Adhesives
Most adhesives are a mixture of a bonding agent and a solvent, which
seep into minute cracks and harden as the solvent evaporates. A few
adhesives, such as super glue and epoxy actually undergo a chemical reaction
as they harden. Silicon based adhesives are used for high temperature
applications such as car muffler repair.
Paints
The components of a paint are a base pigment, a mixture of compounds to
give it a particular color, a binder and a solvent which will evaporate
to give a solid surface. An additional pigment may be added to give a
glossy appearance. Some of the classes of paints are water based, latex,
oil, acyrlic and epoxy based. House paints are formulated for a balance
of durability and reasonable cost. More expensive high durability paints
are used for automobile and aircraft bodies.
Inks
Distinctly different market forces drive the development of different types
of ink. The ink used for newsprint, such as newspapers or paperback novels,
must be cheap and have the consistency of a thick sludge to properly feed
through the ink rollers of a printing press. True color quality is
important for glossy magazines. Flow characteristics are important for pens
and computer printers. The formulation of a good copy machine or laser
printer toner depends upon its electrostatic properties.
Cosmetics
A number of advances in cosmetics have been made in recent years. The
primary changes are in non-allergenic formulations and longer duration
wearability. This is a very competitive market in which a particular look,
marketing or convenient application can sometimes make a product more
profitable than other factors.
Detergents
Detergents are a type of surfactant in that they change the surface tension
of the solution. Recent advances in laundry detergents include bleach
substitutes and the addition of enzymes. An ideal enzyme is one which
efficiently breaks down the organic matter that some stains are made of
while hopefully doing minimal damage to the organic matter which the clothes
are made of. Dish washing detergents are formulated to effectively clean
without damaging the skin of the person doing dishes. Another important
area is industrial detergents which may have far more powerful ingredients
tailored to a particular production process.
Pharmaceuticals
The pharmaceutical industry is one of the few in which there are excellent
formulation courses taught in universities. The formulation aspect of
pharmaceuticals pertains to drug delivery. The usefulness of a drug is
based not only on its effectiveness in treating a condition but also on
how readily it can be administered to the patient. The ideal drug is
in tablet form and bland tasting. Tablets are formulated with additional
ingredients to prevent stomach upset, give a timed release and hold the
tablet together as a solid. Liquid medications must often be mixed with
strong flavorings or alcohol to hide the taste of the medicine.
References
An excellent introduction to the individual application areas is
"Kirk-Othemer Encyclopedia of Chemical Technology" J. I. Kroschwitz,
M. Howe-Grant Eds., John Wiley & Sons (1996)
See the articles on Adhesives, Aerosols, Asphalt, Building Materials,
Cement, Coatings, Colloids, Colorants, Composite Materials, Controlled
Release Technology, cosmetics, Defoamers, Detergency, Dental Materials,
Dispersants, Drug Delivery Systems, Dyes, Emulsions, Enamels, Epoxy Resins,
Explosives & Propellants, Fillers, Film & Sheeting Materials, Flavors &
Spices, Flocculating Agents, Foams, Gelatin, Gums, Hair Preparations, Inks,
Latex Technology, Metallic Coatings, Paint, Paper, Perfumes, Pigments,
Polishes, Refractory coatings, Release Agents, Repellents, Roofing Materials,
Sealants, Soap, Sol-Gel Technology, Sprays, Solders & Brazing Alloys,
Solvents, Surfactants, Tar & Pitch and Waterproofing.
Documents on the web on industrial organic chemistry are at
http://c.chem.ualberta.ca/~plambeck/che/struct/s0909.htm
Documents on the web pertaining to drug formulation are
http://www.clinmark.com/drug-formulation.html
http://w3.ouhsc.edu/bsmith/Drug_Delivery_Systems_I/PHAR%207614%20Syllabus.html.html
Many of the fundamental principles come from physical chemistry. A good
starting point is the sections on solutions, phase equilibrium, surface
chemistry and solids & liquids in
I. N. Levine "Physical Chemistry" McGraw-Hill (1995)
A compilation of techniques for predicting chemical properties is
W. J. Lyman "Handbook of Chemical Property Estimation Methods"
McGraw-Hill (1982)
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