Characterizing the Phase Diagram of Poly(2-Hydroxyethyl Methacrylate-Co-Methyl Methacrylate)

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Characterizing the Phase Diagram of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate)


From the large group of biomaterials found today, polymers are known to be the most common and resourceful, allowing for their extensive use in many areas. Examples of such applications include use as scaffold material in bone repair1 and in microspheres for use in drug delivery systems2. The significant advantage in the use of polymers is the ability to obtain particular chemical, physical and biocompatible properties of the polymer by changing conditions during the polymerization reaction. For example, some polymers are sensitive to fluctuations in reagent concentrations, which can cause differences in polymer morphology, such as increasing its stiffness or porosity. Therefore by understanding the reagent conditions required to obtain particular polymer morphology, it allows for polymers to be synthesized specifically to satisfy the needs of their applications. One way of representing such info is through phase diagrams - graphical representations of phases present at different ranges in reagent composition. These are beneficial in obtaining reagent concentrations for a particular polymer phase without having to test for a large range of conditions. As such, a phase diagram (found in Appendix, Figure A1) was used in this experiment to identify reagent concentrations in order to produce polymers in specific phase regions.

The two monomers used to create the copolymer for this experiment was poly(2-hydroxyethyl methacrylate) (HEMA) and methyl methacrylate (MMA). HEMA is a hydrophilic polymer, causing its homopolymer to form a soft, water swollen gel that is highly porous and insoluble in water3. With the addition of MMA, being a hydrophobic monomer, this can cause changes to the morphology in terms of varying the modulus of the copolymer, creating a gel-like phase, or varying its permeability, creating a spongy phase, depending on the amount of MMA3....