Silicone polymers consist of the repetition of hundreds or thousands of the same or chemically similar molecular units that are called monomers.
A large number of the materials that we encounter in our everyday lives do not exist in nature but, by means of chemical synthesis processes, they are created by the polymerisation of organic compounds. Silicone polymers are usually classified according to the type of reaction that forms them and in this specific instance the Specialist Podiatrist has a choice of two types of silicone that can be used in orthoplastics:
– silicones created by polymerisation by condensation;
– silicones created by polymerisation by poly-addition.
Belonging to the 1st generation of silicones, polymers obtained through polymerisation by condensation have elasticity, hardness and safety properties that are not ideal.
The reaction caused by condensation polymerisation is a random chemical process during which synthesis intermediates or secondary products are released (water, alcohol, gas) responsible for:
Last but not least in importance is the level of toxicity involved in polymerisation by condensation. This process in fact uses a type of liquid catalyst containing dibutyl-tin dilaurate (an irritant and allergenic to the skin), which can bring medium and long-term professional risks such as irritation/inflammation of the skin and, in the event of accidental contact with the ocular mucosa, the formation of blisters.
Belonging to the 2nd generation of silicones, polymers obtained through polymerisation by poly-addition have strong biomechanical properties (elasticity and hardness), maintaining a high level of safety.
The reaction of polymerisation by poly-addition is a controlled chemical process that does not release any synthesis intermediates. As a result there is no risk of creating points of fracture in the orthosis, which will possess good dimensional stability thanks to little or no contraction of the monomeric units.
One further feature of poly-addition polymers is a very quick catalyzation time (3-5 minutes), because the polymerisation reaction is quick and precise. In practical terms, speeding up the silicone polymerisation reaction brings significant benefits for both the Specialist Podiatrist and for the patient.
Poly-addition polymers are obtained by mixing together a base paste (containing vinylsilane) with a catalyst paste (containing organic platinum salts). The correct mixing ration between the two stages (1:1) will produce a final polymer that has an ordered molecular lattice structure. This guarantees the orthosis high quality in terms of hardness, elasticity and inalterability.
As Poly-addition polymers are formulated with a Platinum-based catalyst, unlike condensation polymers, they maintain a high safety profile that will not compromise the health of the skin of either the Podiatrist (who mixes and moulds the materials) or the Patient (who wears the orthosis).
Pursuant to the New Guidelines by the Ministry of Health dated 28/03/2013, relating to health advertising concerning medical devices, in vitro diagnostic medical devices and surgical medical instruments, the user is advised that the information contained therein is exclusively reserved to professional operators.