William Y. Bender
October 17, 2016
Title: “Hard-Soft” Block Copolymers prepared by Hydrosilylation Step-Growth Polymerization
Polymers are linear macromolecules that affect our daily lives in many ways. Styrofoam and plastic bottles are just some examples of these important materials. A polymer is prepared from smaller molecules, monomers, which react together to create larger molecules with a repeating structure and properties that can compete against other materials, such as metals, but are much easier and cheaper to prepare. For these reasons, the ability to prepare new and better polymers is very attractive in many technologies.
In this project, I will be preparing polymers through a step-growth process. This uses two different monomers that can react with each other over and over again. One of these monomers will be a siloxane, which are very flexible. Pure siloxanes are liquids at room temperature and have very high thermal stabilities. The other monomer will be a carbon-based monomer, which are typically solid at room temperature and have very good mechanical properties. By combining these two monomers, I hope to prepare polymers that have the high thermal stability of siloxanes and the good mechanical properties of carbon-based polymers without either of their drawbacks.
We can compare these polymers with crosslinked materials. Adding crosslinks to these polymers will prepare monolithic substances, like rubber. The mechanical properties can be seen by applying a stress (pressure) on the surfaces and measuring the strain (change in shape). The chemical properties of these materials will be assessed using Infrared Spectroscopy (IR). Therefore, we can see the effects of chemistry on the mechanical properties of these materials. By varying the chemistry (types of monomers we use) and number of crosslinks in the material, we expect to be able to control the mechanical properties of the materials we make.
The subject of step growth polymerization is interesting to me as the concepts I have learned so far in organic chemistry are reinforced and enhanced. The types of polymers that can be made are nearly limitless, since there are many different monomers we can use. To begin with, we will primarily be looking at hydridosiloxanes and divinylbenzene reacted using a platinum catalyst in a hydrosilylation reaction.