Addition Polymerization: Chain-growth polymerization where unsaturated monomers add together with no byproduct. The repeat unit has the same empirical formula as the monomer.
Amide Bond (–CO–NH–): The linkage in polyamides (nylons), formed by condensation of –COOH and –NH2 groups with loss of H2O.
Atom Economy: Green chemistry metric = × 100%. Measures efficiency of atom usage.
Bakelite: First synthetic thermosetting polymer, formed by condensation of phenol and formaldehyde. Extensively cross-linked covalent network, used for electrical switches.
Biochemical Oxygen Demand (BOD): Amount of dissolved O2 (ppm) required by bacteria to decompose organic matter in water. Clean < 5 ppm; polluted > 17 ppm.
Biomagnification: Progressive increase in concentration of a persistent substance (DDT, Hg) at successive trophic levels in a food chain.
Buna-S (SBR): Copolymer of butadiene and styrene. Synthetic rubber used in automobile tires.
Caprolactam: 7-membered cyclic amide (lactam); sole monomer for Nylon-6 by ring-opening polymerization. SMILES: O=C1CCCCCN1.
Carothers Equation: Xn = , where p = fractional conversion. Gives degree of polymerization in step-growth polymerization.
CFC (Chlorofluorocarbon): Synthetic compounds (e.g., CCl2F2) that release Cl• radicals in the stratosphere under UV irradiation, catalytically destroying ozone.
Chain-Growth Polymerization: Addition polymerization where high-MW chains form early; monomers react with the active end of a growing chain.
Condensation Polymerization: Step-growth polymerization of bifunctional monomers with loss of a small molecule (H2O) at each step.
Degree of Polymerization (n, Xn): Number of repeat units in a polymer chain. MW = n × M0 (M0 = MW of repeat unit).
Ester Bond (–COO–): Linkage in polyesters , formed by condensation of –COOH and –OH groups.
Eutrophication: Over-enrichment of water with nutrients (N, P) → algal bloom → O2 depletion → death of aquatic organisms.
Gutta-Percha: trans-1,4-Polyisoprene; hard and non-elastic due to regular trans conformation allowing close chain packing.
Greenhouse Effect: Trapping of outgoing IR radiation by atmospheric gases (CO2, CH4, N2O, CFCs), warming Earth's surface.
HDPE: High-density polyethylene, made using Ziegler-Natta catalyst at low pressure. Linear chains, high crystallinity, high tensile strength.
Isoprene: 2-Methyl-1,3-butadiene (C5H8); monomer of natural rubber. SMILES: C=CC(=C)C.
Itai-Itai Disease: Cadmium (Cd) poisoning causing painful bone fractures and kidney failure; first identified in Japan.
LDPE: Low-density polyethylene, made by free radical polymerization at high pressure (1000–2000 atm). Branched chains, low crystallinity, flexible.
London Smog (Classical Smog): Cool, humid smog containing SO2 + particulates/smoke. Reducing in nature.
Melamine-Formaldehyde Resin: Highly cross-linked thermosetting polymer from melamine + formaldehyde. Used for unbreakable crockery.
Minamata Disease: Mercury (Hg, as methylmercury) poisoning causing severe neurological damage; named after Minamata Bay, Japan.
Monomer: Small molecule (repeating unit) that polymerizes to form a polymer.
Nylon-6: Polyamide from ring-opening polymerization of caprolactam (one monomer, 6C). –[NH–(CH2)5–CO]–n.
Nylon-6,6: Polyamide from hexamethylenediamine + adipic acid (two monomers, 6C each). –[NH–(CH2)6–NH–CO–(CH2)4–CO]–n.
PAN: Peroxyacetyl nitrate — secondary pollutant in photochemical smog; lachrymatory (causes eye irritation).
PHBV: Poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate); biodegradable polyester produced by bacteria, used in packaging and medical devices.
Photochemical Smog: Warm, sunny smog containing NO2, O3, PAN, hydrocarbons. Oxidizing in nature; causes eye irritation.
Polyamide: Polymer with amide (–CO–NH–) linkages; e.g., nylon, proteins.
Polyester: Polymer with ester (–COO–) linkages; e.g., Dacron/PET.
Thermoplastic: Polymer that softens on heating and can be repeatedly remolded; only intermolecular forces between chains.
Thermosetting: Polymer that sets permanently on heating due to covalent cross-links; cannot be remolded.
Vulcanization: Treatment of natural rubber with 2–3% sulfur at elevated temperature to form S–S cross-links, improving hardness, elasticity, and temperature resistance.
Ziegler-Natta Catalyst: TiCl4 + Al(C2H5)3; used for coordination polymerization of alkenes to give linear, stereoregular polymers (HDPE) at low pressure.