Tacticity of a linear polymer chain trans conformation Isotactic: -R groups on the same side of the C-C plane Syndiotactic: -R groups on alternating side Atactic: -R groups on either side of the C-C plane...breakage of covalent bonds required to change configuration/tacticity

States of polymers “melt”& solutions “glasses” semi-crystalline Gaseous Liquid Solid decrease temperature or thermal motion

Polymer melt polymer melt is like a bowl of spaghetti entanglements limit motion flows on long-timescales (reptation) elastic on short-timescales viscoelasticity

Melts ( pure polymer “liquid”) towards crystalline solids.. towards crystalline state motion frozen on scale of polymer segmental motion persists

crystalline/amorphous lamellae depends upon cooling rate backbone/sidegroup structure tacticity Å, PE monomers spherulite … to semi-crystalline melts

Some polymers do.. Some don’t (crystallise) Inter-chain hydrogen bonding favors formation of semi-crystalline regions Atactic polystyrene ? Crystallisation is facilitated by “regular” or ordered backbone structure, favorable interchain interactions lower molecular weight nylon-6,6

“glasses”...intermediate between amorphous melts and possible semi-crystalline states... “frozen” structure precedes crystallisation, if it happens; melt conditions glass transition cyrstallisation small scale molecular motions limited backbone motion rotations, “crankshaft” vibrations flips, wags of side groups TgTg TmTm

Q4: Using complete sentences, and schematics if helpful, contrast the chain motion of a melt of atactic polypropylene under (a) slow temperature quench; (b) quick temperature quench Q5: Complete Q4 again, starting from a melt of nylon6,6

Q6: Atactic-polyvinylchloride (PVC) is amorphous, whereas syndiotactic-PVC is partially cyrstalline. But atactic- polyvinylalcohol is partly crystalline. Why? Q7: Do you predict the T m of nylon-6,6 to be higher or lower than that of polyethylene? Why?

Polymer solutions “dilute”, semi-dilute, through to concentrated Rheology: a study of the flow of polymer melts and solutions (shear-thinning, die swell, energy requirements for mold filling, design of mixers, extruders

Block copolymer solutions and melts: making patterned surfaces and ordered melt morphologies

Scientists, academics < 1930s Industrialists 1830 Charles Goodyear,: vulcanised rubber Hevea brasiliensis +  + S elastomeric material 1847 Christian Schonbern Cellulose + nitric acid cellulose nitrate 1860 Leo Baekeland (Bakelite) phenol-formaldehyde resin 1930s DuPont (USA) nylon, teflon 1938Dow (USA) polystyrene 1939 ICI (UK) LDPE WWII: shortage of natural rubber! “A damned gooey mess” Another failed synthesis

Scientists begin to look at complex systems ’s Hermann Staudinger, German Physical Chemist “long-chained molecules or macromolecules” interacting, separate very long, alkane-like intermediate speciesbut misunderstood. e.g., T m, flow behaviour flexibility