Writing a Winning Business Plan ◾ 307
A polymer is a large molecule constructed from many smaller structural units called
rs, which are covalently bonded together. Polyurethanes are among the most
portant classes of polymers because of their unique physical and chemical properties. In
dition to a significant number of urethane groups, polyurethanes may contain aliphatic and
omatic hydrocarbons, ester, ether, amide, and urea groups.
Polyurethane was originally developed by Professor Otto Bayer in 1937, who was trying
develop fibers to compete with nylon. In the following year, the DuPont Company
veloped a polyester type polyurethane based on diisocynate chemistry and it becam
e basis of most products made from polyurethanes for the next quarter of a century. In
62, Johannes Mirkovitch, Ph.D. first used the polyester polyurethane for making artificial
ns. Unfortunately, this polyester material was attacked by the body’s enzyme systems and
drolyzed.
e use of polymers in medical applications and devices continued to increase over the
ars as the search went on for a more stable polyurethane for implantable devices. In 1967
hn W. Boretos, Ph.D. and William Pierce, M.D., Ph.D. introduced Biomer
R
, a segmente
lyether-type polyurethane, for biomedical applications such as artificial hearts. Biomer
R
me the yardstick by which all other polyurethanes were measured because it had the
xure endurance characteristic of any polyurethane. In 1971, Emery Nyilas, Ph.D. developed
terial called Avcothane
R
which advanced polyurethanes through the addition of silicone and
de the polyurethane even more blood compatible.
In 1977, the Upjohn Company introduced a thermoplastic polyurethane, trade name
llethane
R
, as an alternative biomedical material. Because Pellethane
R
is a thermoplastic,
could be processed more cheaply and made more dimensionally precise. Concern over
e implantation of polyurethanes began to increase in the late 1970s because of harmful
tances which might be released during biodegradation. en, in 1978, ermedics, Inc.
troduced an aliphatic polyurethane called Tecoflex
R
. Because of its chemical structure,
coflex
R
could not form carcinogenic amines if it degraded in the body. However, Tecoflex
R
s not suitable for long-term implants.
Confidential PolyMedica Industries, Inc.