Chemistry of Synthesis A. Condensation Polymerization (functionality ≥ 2) diol diacid polyester diamine diacid polyamide x : degree of polymerization (DP) No 1 No－ N Xn = = (P = , extent of reaction) N 1 － P No 1 + P Xw = (most probable distribution) 1－ P Weight-fraction distribution for linear step-growth polymers ex) PET (polyethylene terephthalate) Nylon 6 caprolactam

B. Addition Polymerization · Initiation ex) Free radical polymerization benzoylperoxide · Propagation · Termination recombination disproportionation * ΔH ? = breaking first + 260kJ (흡수) - new C-C bond －365kJ (방출) ΔH = －105 kJ/mol → autoacceleration and gel effect (Tromsdorff effect) ex) vinyl polymer X = －H polyethylene (PE) －Ph polystyrene (PS) －Cl polyvinylchloride (PVC) －CH3 polypropylene (PP) －CN polyacrylonitrile (PAN)

Molecular Structure of Polymers A. Linear, Branched, Cross-linked or Network linear branched crosslinked * A scale model of a typical linear polymer molecule → 0.5㎛ diameter and 3m long clothesline B. Copolymers random alternating graft block

Industrial Polymerization Methods A. Bulk, Solution, Suspension, Emulsion Polymerization bulk solution suspension emulsion structure in emulsion polymerization

B. Gas-phase Olefin Polymerization (fluidized-bed reactor : Union Carbide 100℃, 10기압 미만) C. Tubular Low Density Polyethylene Process (plug-flow reactor) (LDPE : 1000∼3400기압, 150 ∼300℃)

Crosslinked or Network Polymer Thermosets (열경화성 수지) Crosslinked or Network Polymer ex) FRP (fiber reinforced unsaturated polyester) prepolymer x=8∼10 y x unsaturated linear chains styrene · Phenolics phenol + formaldehyde → plastic bakelite · Epoxy resin epoxy + diamine or diacid → cross-linked · Amino resin urea + formaldehyde → cross-linked melamine

Thermoplastics (열가소성 수지) Soften upon heating and reversible regain their solid nature A. Amorphous (無定形) · Polymethylmethacrylate (PMMA) · Polystyrene (PS) · Polycarbonate (PC) · Styrene Acrylonitrile (SAN) B. Crystalline (結晶性) · Polyethylene (PE), Vinyl polymers, Nylon, PET … * Commodity plastics and Engineering plastics : Acetal, Poltamide, Polysulfone, Polyetherimide … … Specific volume Temperature Tm Tg E D F C B A A : 액체 B : 고점도 액체 C : 과냉각 액체 D : 유리성 고체 E : 과냉각 액체기지에서의 고체 결정영역 F : 유리성 기지에서 비결정성과 부분적으로 결정성인 열가소성 수지의 냉각과 응고시 온도에 따른 비체적의 변화

Molecular Weight (Mw) and Molecular Weight Distribution (MwD) Mw = x M0 M0 : the molar mass of the repeat unit x : the degree of polymerization Mn amount of polymer Mw Mw ∑ ni Mi Mn = ; number-average Mw ∑ ni ∑ wi Mi Mn = ; weight-average Mw ∑ wi Mn ; polydispersity or heterogeneity index

What is a Polymer? A. Natural polymers and Synthetic polymers The word polymer ; many parts (from the Greek, polus : many and meros : parts, segments) * monomer (monos; single) * repeat unit ex) A. Natural polymers and Synthetic polymers · Natural fibers or man-made fibers · Natural rubbers or synthetic rubbers · Biological polymers : protein, polysaccharide, collagen, etc · Inorganic polymers : inorganic glasses B. Classification of Polymers Thermoplastics Elastomers Thermosets Coating & Adhesives Crystalline Amorphous Polymers