Paris - A group of French researchers has published a paper on self healing rubberÂ in the
prestigious science journal, Nature (Vol 451, 21 Feb 2008) today. The paper is titled, Self-healing and thermo-reversible rubber from supramolecular
assembly and describes a type of rubber which can survive small cuts
repeatedly. These small cuts can repeatedly heal themselves at
room temperature.Â The researchers say the rubber is based on fatty acids and urea.
In the paper, the researchers say, "In striking contrast to
conventional cross-linked or thermoreversible rubbers made of
macromolecules, these systems, when broken or cut, can be simply
repaired by bringing together fractured surfaces to self-heal at room
The self-healing happens spontaneously when two freshly cut surfaces
are brought together. The cut surfaces begin to merge almost
immediately. Even after around 15 minutes, says the paper, the
materials can withstand strains of 100 to 200 percent. The healing then
continues over the following three to four hours. Following the
self-healing, the samples regain the potential to deliver strains of
several hundred percent with low creep, claims the paper.
At room temperature, self-healing is no longer possible after a week or
so. This interval reduces rapidly at higher temperatures, to about 48
h waiting time at 40C, 95 min at 60C, 15 min at 90C, and 5 min at
The lead author on the paper is Philippe Cordier at Ecole Superieure de Physique et Chimie Industrielles (CNRS-ESPCI) in Paris.
The paper describes the production method thus: "Compound A is obtained
at the 100 g scale in two steps. 175 g of Empol 1016 supplied by Cognis
(mixture of 4% monoacid, 79% diacid, 17% triacid and polyacids) was
condensed with 70.3 g of diethylenetriamine at 160C under nitrogen over
24 h. 72 g of oligo-amidoamine with a [CH2-CONH] to [CH2-NH2] ratio of
1.8 as determined by NMR obtained after elimination of unreacted amine
(chloroform/water extractions) was then reacted with 17 g of urea at
135-160C for 7.5 h under nitrogen, whereupon ammonia and unreacted urea
were extracted by vacuum stripping and water washings. The material was
dried under vacuum and pressed at 120C into steel moulds of 100 cm2 area
at 32mm depth. Swelling with dodecane was achieved at 60C over 24 h."
Story at Nature magazine