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CHEM219/ CHEM 219 Module 8 – Principles of
Organic Chemistry with Lab | Portage Learning |
Updated 2026–2027 | Complete Questions &
Verified Answers | Grade A
2026 / 2027 Academic Year
Q: Polymer
Answer large molecule made by repetitive linking of smaller units (monomers)
Q: Macromolecule
Answer very large molecule composed of thousands of covalently bonded atoms (ex: polymer)
Q: two ways polymers are made
Answer
- natural (in nature)
- synthetic (in lab)
Q: examples of natural polymers
Answer rubber, carbs: starch & cellulose, proteins, nucleic acids DNA, RNA
Q: examples of synthetic polymers
Answer nylon, teflon, styrofoam, polyethylene, Dacron,
Q: 3 main ways to differentiate polymers
Answer
- method of formation
- final composition
- stereochemical orientation
Q: Two types of Synthetic polymers
Answer
- chain-growth
- step-growth
Q: chain growth polymers are also know as:
Answer addition polymers
Q: How are chain growth polymers made?
Answer made by addition of one monomer unit to another in a repetitive pattern
Q: Polypropylene
Answer chain-growth polymer: polypropylene monomer: H2C=CHCH carpet fibers, car parts, toys, packaging, houseware
Q: Orlon, Acrilan, Creslan
Answer chain-growth polymer: polyacrylonitrile monomer: H2C=CH(CN) textiles/fibers, carpets, upholstery
Q: Polyvinyl Acetate
Answer chain-growth polymer: polyvinyl acetate monomer: H2C=CH(OCOCH3) elmers glue, silly putty, latex paints
Q: Polyvinyl alcohol
Answer chain-growth polymer: polyvinyl alcohol monomer: H2C=CH(OH) eye med- artificial tears
Q: Plexiglass (Lucite)
Answer chain-growth polymer: polymethylmethacrylate monomer: H2C=C9CH3)COOCH clear plastic sheets , blocks, and tubing
Q: the final polymer retains all of the atoms of the monomer
Answer the final polymer retains all of the atoms of the monomer
Q: step growth polymerization
Answer formed by the reaction between 2 different functional groups on different monomer molecules with the accompanying loss of some small molecule (typically water)
Q: Polyamide (Nylon)
Answer formed by combining 1,6-diaminohexane (amine) with 1,6-hexandioic acid (carboxylic acid) amine functionality reacts with carboxylic acid functionality to form an amide with a corresponding loss of a water molecule naturally occurring step-growth/ condensation polymer examples Answer cellulose, polypetide chains, beta-Hydroxybutyric acid Lexan Answer step-growth polymer: polycarbonate eye glasses, auto parts, drinking glasses Kevlar Answer step-growth polymer: polyamide body armor, tires, helmets Dacron, Mylar Answer step-growth polymer: polyester
eletric/thermal insulation, helium balloons, artificial limbs three main mechanisms for addition/ chain-growth polymerization Answer
- free radical
- cationic
- anionic For all three main addition mechanisms, how does polymerization begin? Answer (initiation) begins by creating a reactive intermediate that starts the chain reaction free-radical addition polymerization Answer a monomer reacts with a free-radical initiator to create a free-radical free-radical Answer an atom or a group of atoms that has one unpaired electron radical initiator Answer a reagent that creates radicals, has relatively weak covalent bonds which can be homolyzed
what happens after the radical initiator has formed radicals? Answer radical can attack + homolyze C=C of monomer to create a reactive intermediate that starts polymerization which substituent does the radical add to in the monomer? Answer adds to the LEAST substituted carbon of the C=C bond because this carbon is easier to approach and less hindered to produce a more stable radical intermediate What happens during propagation of free-radical polymerization? Answer produces a new radical that can continue the polymerization chain reaction: Each attack of the radical with a new monomer unit extends the chain by one unit what is chain propagation the same as? Answer some step as initiation in that monomers add in head to tail fashion with substituents present on alternating carbons in the chain What 4 main factors determine the extent of the polymerization?
- temperature
- pressure
- solvent used
- monomer concentration
speed of free radical chain growth Answer extremely rapid- can grow by thousands of monomers in less than a second Termination of free-radical polymerization Answer stops the chain growth, involves 2 radical species- pairing of 2 unpaired electrons and formation of new covalent bond 2 pathways of termination Answer
- Radical Coupling
- Radical Disproportionation Radical Coupling termination of free-radical polymerization where 2 radicals combine using the unpaired electrons on each to make a new covalent bond monomer arrangement in radical coupling head-to-head arrangement, substituents are attached to adjacent carbons radical disproportionation One radical abstracts a hydrogen atom from another radical species which forms a new covalent bond and makes and alkane- then an alkene is formed by the combination of unpaired electrons on adjacent carbons Radical Coupling AND radical disproportionation form what type of species from radical
Cation Chain-Growth Polymerization best for substrates that can form stable carbocation intermediates (typically unsubstituted substrates like bulky alkenes or alkenes with electron-donating substituents) How is cation addition polymerization initiated? By adding a strong acid to an alkene to form a carbocation intermediate cation addition polymerization propagation carbocation intermediate + new alkene monomer molecule adds one unit to the polymer chain each time cation addition polymerization termination terminates by the removal of a hydrogen atom from a carbon atom adjacent to the positively charged carbon to form an alkene (like in an elimination reaction) Anionic addition polymerization a form of chain-growth polymerization or addition polymerization that involves the polymerization of monomers initiated with anions. The type of reaction has many manifestations, but traditionally vinyl monomers are used. Why use anionic addition polymerization useful for alkenes with electron-withdrawing substituents such as cyano groups, phenyls, esters main catalysts used for anionic addition polymerization Grignard Reagents (R: - [MgBr]+) Alkyllithium (R:-Li+)
anionic addition polymerization propagation chain grows by 1 anionic intermediate adding to the C=C bond of a monomer molecule. monomer anion adds in place of a Grignard Reagent or Alkyllithium reagent. each addition grows by one unit anionic addition polymerization termination accomplished by quenching reaction with a proton source such as water or alcohol what is formed when a monosubstituted alkene monomer is polymerized? a new chiral center is formed at every position where the substituent branches from the back bone of the chain Tacticity describes the location in the polymer chain of chiral centers rather than using R or S designation 3 main classes of polymer tacticity
- Atactic
- Isotactic 3.Syndiotactic atactic stereocenters have random configurations Isotactic
Site Control The specific shape of the reagent or catalyst that facilitates the reaction also determines the stereochemistry. Ziegler-Natta catalyst most famous site control to prod stereoregular polymers. uses various transition metal catalysts to control sites where monomers are added to the chain Ligands A molecule that binds specifically to a receptor site of another molecule.
- coordinated to the metal ion that bind monomers prior to insertion into the growing chain
- specifically utilized in Ziegler-Natta catalysts what 2 factors of ligands orient monomers into position shape and size hold monomers into position in ONE orientation what two types of polymers can Ziegler-Natta catalysts be used on? Isotactic and Syndiotactic (only stereoregular polymers) Homopolymer a polymer made up of one type of repeating unit. It is made from one monomer only. Copolymer polymers composed of more than one type of monomer
- used to control properties of a polymer product (like flexibility or chemical resistance) Random (Statistical) Copolymer
monomeric units distributed randomly and unevenly in the chain Alternating Copolymer monomeric units distributed regularly + alternating with nearly equimolar amounts in each chain Block Copolymer long sequence/ blocks of one monomer is joined to a block of the second monomer Graft Copolymer side chains of a given monomer are attached to main chains of a second monomer biggest causative agent of the exact sequence in copolymer chains: relative reactivity of the monomers present situation creates what copolymer? A reacts rapidly with B but slow with self B reacts rapidly with A but slow with self alternating sequence (ABABABABABA) situation creates what copolymer? A and B are equally reactive towards each other and self random sequence (ABBAAAAABABBBAABBBBBBBAABABBB) two things that determine the reactivity of a monomer
- number of substituents present
- type of substituents present
Amorphous polymers polymer chains arranged in random manner- not regularly aligned as in a crystal important example of an amorphous polymer polystyrene (monomer styrene ((Vinyl Benzene))) thermoplastic softens upon heating and hardens upon cooling (property of polystyrene) what is produced by adding a low boiling inert solvent like pentane to the polymerization reaction of polystyrene where the pentane boils off into gas and the volatilization causes bubbles that expand the polymer into a foam. Styrofoam What allows amorphous polymers to be made more rigid/ crystalline (and thus less amorphous) Cross-Linking Cross-linking definition small amounts of polyfunctional monomers are added to form links (covalent bonds between growing chains) these links tether the growing chains together in a less random, more crystalline order characteristics of cross-linked polystyrene more rigid, less soluble in organic solvents than native what are the main properties that characterization techniques of polymers seek to discover? molecular mass, molecular structure, morphology, thermal properties, mechanical
properties molecular mass of polymers differs from typical molecules d/t polymerization reaction producing a distribution of molecular weights and shapes molecular mass of polymers = average molecular weight and polydispersity Polydisperity (PD) how heterogenous the range of particle size is Spectroscopy: UV-visible, infrared, Ramen, Nuclear magnetic resonance, electron spin resonance, xray diffraction, mass spectrometry techniques used to characterize polymers by identifying common function groups + other structure features (also used to determine molecular structure of unknown molecules) an atom has gained or lost electrons ion a characteristic of atom that varies regularly across the periodic table periodic property a compound held together by a shared pair of valence electrons covalent compound a compound formed by ions
