Chemistry 367L/392N

Macromolecular ChemistryMacromolecular Chemistry� Welcome to CH367L and CH392N

Chemistry 367L/392N

Chemistry 367L / 392NChemistry 367L / 392N

�� IntroductionIntroduction––SyllabusSyllabus

––Graduate PresentationsGraduate Presentations

––QuestionsQuestions

––Some HistorySome History

Macromolecular ChemistryMacromolecular Chemistry

Chemistry 367L/392N

"I just want to say one word to you -- just one word -- plastics."

Advice given to Dustin Hoffman's character in The Graduate

Chemistry 367L/392N

Organic Polymer ChemistryOrganic 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

Chemistry 367L/392N

““PlasticsPlastics”…”…

� 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

Chemistry 367L/392N

Natural PolymersNatural 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

Chemistry 367L/392N

More examples of Natural polymersMore 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)

Chemistry 367L/392N

Some early MilestonesSome 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.

Chemistry 367L/392N

What are Polymers??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.

Chemistry 367L/392N

MeyerBaekeland

The History of Novolac

C.H. Meyer and/or L.H. Baekeland Discovered Novolac ca. 1900 ???

OH

CH3

Chemistry 367L/392N

Novolac Resin Production!!

Workers at Albert Co. in Wiesbaden, Germany“zerkleinert das Harz von Hand” (ca. 1910)

Chemistry 367L/392N

Bakelite and ShellacBakelite and ShellacBaekeland’s Phenol-formaldehyde

resins, which he called Bakelite.

Chemistry 367L/392N

StaudingerStaudinger’’s Heretic Proposals Heretic Proposal

O

O

O

O

CH3CHCOCH2CH3

O

OH

Polymer

Chemistry 367L/392N

Hermann Staudinger Hermann Staudinger

18811881--19651965

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.

Chemistry 367L/392N

ColligativeColligative PropertiesProperties

�� ColligativeColligative properties of solutions are properties of solutions are properties that depend upon the properties that depend upon the concentration of solute molecules or ions, concentration of solute molecules or ions, but not upon the identity of the solute. but not upon the identity of the solute. ColligativeColligative properties include freezing point properties include freezing point depression, boiling point elevation, vapor depression, boiling point elevation, vapor pressure lowering, and osmotic pressure. pressure lowering, and osmotic pressure.

Chemistry 367L/392N

Freezing Point DepressionFreezing Point Depression

∆∆TTff = = -- i i KK ff CCmm

�� freezing point depression freezing point depression ∆∆TTff is a is a colligativecolligative property property of the solution, and for dilute solutions is found to be of the solution, and for dilute solutions is found to be proportional to the proportional to the molalmolal concentration Cconcentration Cmm of the of the solution. solution. KK ff is called the freezingis called the freezing--pointpoint--depression depression constant for the solvent (1.86 constant for the solvent (1.86 ººC/kg/mol for HC/kg/mol for H22O) O) and i and i is the is the thethevan'tvan'tHoff factorHoff factor which represents the number of dissociated moles of particles per mole of solute

�� For sucrose, i = 1; for For sucrose, i = 1; for NaClNaCl, i = 2 and for CaCl, i = 2 and for CaCl22, i = 3, i = 3

Chemistry 367L/392N

If the total mass of dissolved material is known, depresssion of freezing point, elevation of boiling point, and osmotic pressure, colligativeproperties 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.

Science Wins

Chemistry 367L/392N

Herman Francis MarkMay 3, 1895 — April 6, 1992

Hans Mark

Chemistry 367L/392N

XX--Ray Crystal StructuresRay Crystal Structures

Mark and Staudinger fight over stiffness

Chemistry 367L/392N

Wallace Hume Carothers 1896Wallace Hume Carothers 1896--19371937

Inventor of Nylon ... US patent 2,130,947

see http://www.invent.org/hall_of_fame/28.html

Chemistry 367L/392N

Wallace Hume Carothers 1896Wallace Hume Carothers 1896--19371937

Chemistry 367L/392N

CommercializionCommercializion of Nylonof Nylonttp://www.chemheritage.org/EducationalServices/chemach/pop/whc.http://www.chemheritage.org/EducationalServices/chemach/pop/whc.htmltml

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.