Macromolecular Chemistry Welcome to CH367L and CH392N
Macromolecular Chemistry Introduction Syllabus Chemistry 367L / 392N Graduate Presentations Questions Some History
Advice given to Dustin Hoffman's character in The Graduate "I just want to say one word to you -- just one word -- plastics."
Organic Polymer Chemistry Polymer: from the Greek, poly + meros, many parts. Any long-chain molecule synthesized by linking together repeat units called monomers Monomer: from the Greek, mono + meros, single part. The simplest non-redundant unit from which a polymer is synthesized Plastic: a polymer that can be molded when hot and retains its shape when cooled.also more precisely a thermoplastic
Plastics Thermoplastic: a polymer that can be melted and molded into a shape that is retained when it is cooled Thermoset: a polymer that can be molded when it is first prepared, but once it is cooled, hardens irreversibly and cannot be remelted
Natural Polymers Natural polymeric materials have been used throughout history for clothing, decoration, shelter, tools, weapons, and writing materials Examples of natural polymers: Cellulose (wood, cotton) Hair (wool) Silk Rubber Horn Modified natural polymers Nitrocellulose (lacquer, smokeless powder) Rayon, etc
More examples of Natural polymers Polyesters Polylactic acid Polyhydroxyalkanoates Proteins Silk Soy protein Corn protein (zein) Polysaccharides Xanthan Gellan Cellulose Starch Chitin Polyphenols Lignin Tannin Lipids Waxes Specialty polymers Shellac Natural rubber Nylon (from castor oil)
Some early Milestones 1833 Berzelius coins term polymer 1880-1900 Man made fibers by modification of natural material cellulose acetate, nitrocellulose, etc 1900-1930 Colloid Controversy 1910 Bakelite 1920 Staudinger macromolecules 1930-1937 the Carothers period Neoprene, nylon,etc.
What are Polymers?? Jöns Jacob Berzelius (1779-1848) Coined the term "polymer" in 1833 to describe organic compounds that share identical empirical formulas but differ in overall molecular weight a kind of isomer.. acetylene cyclobutadiene, benzene and styrene, for example. This concept lasted until Carothers.
The History of Novolac C.H. Meyer and/or L.H. Baekeland Discovered Novolac ca. 1900??? OH Baekeland CH 3 Meyer
Novolac Resin Production!! Workers at Albert Co. in Wiesbaden, Germany zerkleinert das Harz von Hand (ca. 1910)
Bakelite and Shellac Baekeland s Phenol-formaldehyde resins, which he called Bakelite.
Staudinger s s Heretic Proposal CH 3 CHCOCH 2 CH 3 OH O O O O O Polymer
Hermann Staudinger 1881-1965 1965 The statement of a German chemist after a debate with Staudinger in 1926: We are shocked like zoologists would be if they were told somewhere in Africa an elephant was found who was 1600 feet long and 300 feet high. Staudinger received the Nobel Prize in chemistry in 1953.
Colligative Properties Colligative properties of solutions are properties that depend upon the concentration of solute molecules or ions, but not upon the identity of the solute. Colligative properties include freezing point depression, boiling point elevation, vapor pressure lowering, and osmotic pressure.
Freezing Point Depression T f = - i K f C m freezing point depression T f is a colligative property of the solution, and for dilute solutions is found to be proportional to the molal concentration C m of the solution. K f is called the freezing-point point-depression constant for the solvent (1.86 ºC/kg/mol for H 2 O) and i is the the van't Hoff factor which represents the number of dissociated moles of particles per mole of solute For sucrose, i = 1; for NaCl,, i = 2 and for CaCl 2, i = 3
Science Wins If the total mass of dissolved material is known, depresssion of freezing point, elevation of boiling point, and osmotic pressure, colligative properties give an easy way to estimate the molecular weight of the substance. Eventually, the tiny osmotic pressures and freezing point depressions seen in polymer solutions could no longer be ignored, or attributed to small amounts of a low molecular weight impurity.
Herman Francis Mark May 3, 1895 April 6, 1992 Hans Mark
X-Ray Crystal Structures Mark and Staudinger fight over stiffness
Wallace Hume Carothers 1896-1937 1937 Inventor of Nylon... US patent 2,130,947 see http://www.invent.org/hall_of_fame/28.html
Wallace Hume Carothers 1896-1937 1937
Commercializion of Nylon ttp://www.chemheritage.org/educationalservices/chemach/pop/whc.html tml Nylon was first used for fishing line, surgical sutures, and toothbrush bristles. DuPont touted its new fiber as being "as strong as steel, as fine as a spider s web," and first announced and demonstrated nylon and nylon stockings to the American public at the 1939 New York World s Fair. DuPont sold 5 million pairs of stockings across the U.S. on the first day they were generally available, May 15, 1940. About 63 million were sold in their first year.