Molecular shape plays an important role in the successful manufacture of contact

Question

Molecular shape plays an important role in the successful manufacture of contact lenses. The original hard contact lenses were based on methyl methacrylate, MMA (panel A). Adding molecules that pack less efficiently makes pores in the lens, allowing oxygen to penetrate; the result is called breathable lenses. The molecules abbreviated TRIS and HFIM (panel A) are two examples. A soft lens is based on a molecule that absorbs water. Analyze the shapes of TRIS and HAM, indicating the origin of the poor packing. Of the molecules in panel B, which might be used as the basis of a soft contact lens? What is the site for hydrogen bonding, if any, for molecules in panel B?

Explanation / Answer

In panel A the molecules are bulky and very sterically hindered TRIS and HFIM. This bulkiness leads to poor packing and stacking of the molecules /polymer making it softer.

In panel B the molecule MAA has a hydroxy group( of COOH) which can form hydrogen bonds with Nitrogen of DMA and oxygen of EDA and TMSM.

To make soft contact lensTMSM of panel B should be added to PMMA as it is very sterically hindered and bulky which makes it less compactly packed.

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.