1. Polymer Synthesis CHEM 421 Polymer Parameters Chemical structure –Chemical composition and distribution –Sequence length and distribution Molecular weight and distribution Chain isomerism Morphology Topology Additives Cost

2. Polymer Synthesis CHEM 421 Hierarchical Fiber Morphology “skin” “core” macrofibril (~1 µ m diameter) microfibril (50 nm)

3. Polymer Synthesis CHEM 421 Folded Chain Crystal Habit polymer melt crystallization

4. Polymer Synthesis CHEM 421 Polytehylene

5. Polymer Synthesis CHEM 421 Polyethylene

6. Polymer Synthesis CHEM 421 Fiber Drawing semicrystalline lamellae microfibril

7. Polymer Synthesis CHEM 421 Mechanical Properties crystalline amorphous6 GPa 320 GPa microfibril

8. Polymer Synthesis CHEM 421 Mesogens (liquid crystals)

9. Polymer Synthesis CHEM 421 Crystal & Isotropic Liquid Long-range order - orientational - translational

10. Polymer Synthesis CHEM 421 Polyphenyls

11. Polymer Synthesis CHEM 421 Crystal  Mesophase  Isotropic

12. Polymer Synthesis CHEM 421 Nematic LC Long-range order - orientational

13. Polymer Synthesis CHEM 421 Polyphenyls

14. Polymer Synthesis CHEM 421 N versus S A

15. Polymer Synthesis CHEM 421 N, S A, S C

16. Polymer Synthesis CHEM 421 Typical Calamitic Mesogen n = 6

17. Polymer Synthesis CHEM 421 Mesogens

18. Polymer Synthesis CHEM 421 Calamitic vs. Discotic Nematics

19. Polymer Synthesis CHEM 421 Polymer Liquid Crystals

20. Polymer Synthesis CHEM 421 PLCs Thermodynamics

21. Polymer Synthesis CHEM 421 Liquid Crystalline Polymers (LCPs) 1970’s: lyotropic LCPs (Kevlar) - ultra-high strength fibers 1980’s: thermotropic Polyesters - stronger, low CTE, low viscosity,

22. Polymer Synthesis CHEM 421 Ultra-high Strength Polymers Poly(p-benzamide)s 1967 Stephanie Kwolek & Paul Morgan (DuPont) react diamines with diacids

23. Polymer Synthesis CHEM 421 “Stronger than steel?”

24. Polymer Synthesis CHEM 421 Origin of Strength? “skin” “core” macrofibril (~1 mm diameter) microfibril (50 nm) extended-chain crystal habit

25. Polymer Synthesis CHEM 421 I to N Transition

26. Polymer Synthesis CHEM 421 Liquid Crystalline Polymers (LCPs) 1970’s: lyotropic LCPs (Kevlar) - ultra-high strength fibers 1980’s: thermotropic Polyesters - stronger, low CTE, low viscosity, Key: Inexpensive monomers.

27. Polymer Synthesis CHEM 421 Liquid Crystalline Polymers (LCPs) Some introductory literature E. T. Samulski “The Mesomorphic State”, Chapter 5 in Physical Properties of Polymers, 3 rd Edt, Cambridge University Press (2004) D. Acierno and A. A. Collyer, Rheology and Processing of Liquid Crystal Polymers, Chapman & Hall (1996) N. A. Plate, Editor. Liquid Crystalline Polymers, Plenum Press, NY (1993). A. A. Collyer, Edt. Liquid Crystal Polymers: From Structures to Applications, Elsevier Applied Science Publishers, London (1992). A. M. Donald and A. H. Windle, Liquid Crystalline Polymers, Cambridge University Press (1991)