1. Polymethyl Methacrylate
(PMMA)

2. Monomer
Methyl Methacrylate (MMA)
Formula : H2C = CHCOOCH3
Structure :

3. Formation
Free Radical Polymerization

4. Step 1 : Free radical (R*) plus methyl methacrylate→

5. Step 2 : Polymerization - MMA radical plus MMA :repeated many, many times
Step 3 : Termination – occurs when two radicals join

6. Catalysts
Multiple catalysts can be used in production of PMMA. Some of these are:
Butyl Lithium
Highly active catalysts based on group 4 metallocenes
An aluminum system supported by salen ligands

7. Why Use Different Catalysts?
Different catalysts result in different versions of the polymer
Variation is due to the placement of the ester (R-O-R) and methyl (CH3) groups along the polymer backbone

8. Isotactic – similar groups on same side of chain
Syndiotactic – two groups alternate
Atatactic – displays no regular pattern
Every other carbon in the chain is a steriocenter
Isotactic and Syndiotactic forms are more crystalline in nature and are stronger and more resistant to solvents

9. History of PMMA
Developed by three companies at approximately the same time in 1928
Röhm and Haas
Du Pont
ICI (Imperial Chemical Industries)
First came on market 1933

10. Historical uses of PMMA
Du Pont first used PMMA primarily for cast products (rods, tubes, and blocks)
ICI and Röhm and Haas focused on producing sheets of PMMA to be used as safety glass
Röhm and Haas introduced Plexiglass to market in 1936 and ICI followed with Perspex later that same year

11. Properties of PMMA
Lighter than glass (density is about half that of glass)
Shatter proof
Softer and easier to scratch than glass (scratch resistant coatings may be applied)
Transmits more light than glass (92% of visible light)
Does not filter UV light (may be coated with UV film)
More transparent than glass, so windows can be made thicker

12. Current uses for PMMA
Include many uses similar to those for which it was first developed but include many things never imagined by the inventors! A partial list of the uses for PMMA includes:

13. Safety glass such as Plexiglass and Lucite – uses range from windows for aquariums and under-water restaurants to safety shields at hockey rinks to skylights in your home to simple paperweights

14. Medical Uses
Used as bone cement for use in arthroplastic procedures of the hip, knee, and other joints for the fixation of polymer or metallic prosthetic implants to living bone
Used in Pacemakers

15. Dentures!

16. Artificial eye lenses used for cataract surgery
Suspended in collagen and implanted to reduce wrinkles in cosmetic procedures

17. Acrylic Paints
Acrylic “latex paints” often contain PMMA suspended in water

18. Blacklight Tattoo Ink
Made of 97.5% PMMA and 2.5% microspheres of fluorescent dye suspended in UV sterilized, distilled water with no preservatives or other additives
The ink received USFDA approval in 1995 for use in animals, plants and fish for the purpose of tracking migration, growth patterns; breeding habits etc.

20. Breakdown of PMMA Autoignites at 445° C (833° F)
Burns cleanly to produce H2O and CO2
Virtually smokeless combustion
Has superior recyclability
Can be reground and reused
Can be depolymerized back to monomer, purged of impurities, and reploymerized back to PMMA

21. Potential Toxicity PMMA is an essentially non-toxic material MMA
No workplace exposure limits
MMA
Respiratory effects may result from chronic low level exposure or from short term acute exposure
Exposure primarily occupational (production of monomer and its polymers, doctors, nurses, dentists, and dental technicians)

22. Ingestion of PMMA/MMA Oral LD50 (in rats) PMMA = 11,700 mg/kg
Oral LD50 (in rats) MMA – 7,872 mg/kg