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MatE 21 > (Concept) POLYMERS > Flashcards

(Concept) POLYMERS Flashcards

1
Q

Macromolecule built up by the repetition of small chemical units joined by covalent bonds

A

Polymers

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2
Q

Bonds present in polymers

A

Covalent

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3
Q

Other name for repeat unit

A

“Mer”

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4
Q

The sequential reactions of monomers/oligomers to form a polymer chain

A

Polymerization

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5
Q

What are the polymerization mechanisms?

A
  1. Chain-reaction (Addition) | 2. Step-growth (Condensation) | 3. Ring-Opening
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6
Q

Where does sequential addition of monomer units occurs?

A

At an active center

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7
Q

How does an active center form?

A

Through a reaction between an initiator (or catalyst) species and the monomer unit

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8
Q

Steps in chain-reaction (Addition)

A

Initiation, propagation, and termination

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9
Q

An active site is also a/an…

A

Unpaired electron (or a free radical din (?))

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10
Q

How does step-growth (condensation) occur?

A

Through a series of step-wise reactions in which any 2 molecules (monomers, dimers, trimers, etc.) may react at any time.

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11
Q

Where does step-growth (condensation) happen?

A

Between chemically reactive groups

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12
Q

Are there any eliminations in step-growth (condensation) reactions?

A

Yes, usually a small molecule
is eliminated.

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13
Q

What is ring-opening polymerization mechanism?

A

The breaking of cyclic molecules and their subsequent formation of a linear polymer

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14
Q

Chain-reaction (addition) may be differentiated through…

A

Presence of double bonds/alkenes monomers

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15
Q

Consists of only one repeating unit

A

Homopolymer

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16
Q

Has more than one repeating unit

A

Copolymer

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17
Q

Arrangements possible in copolymer structures

A

Random, alternating, block, or graft

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18
Q

Refers to the atomic composition and chemical structure of the monomer

A

Primary Structure

19
Q

Refers to the size and shape of a single polymer molecule

A

Secondary Structure

20
Q

Refers to the intermolecular bonding forces and structural order of the polymer

A

Tertiary Structure

21
Q

Refers to the number of bonds that a given monomer can form

A

Functionality

22
Q

Refers to monomers with an interlinking capacity of 2.

A

Difunctional Monomers

23
Q

Refers to monomers with an interlinking capacity greater than 2.

A

Polyfunctional Monomers

24
Q

This indicates the number of repeating units strung together

A

Degree of Polymerization

25
Q

Is there an increase or decrease for the following: (1) mechanical properties, (2) melting temperature, and (3) mechanical strength, (4) viscosity, when there is a higher DP?

A

Increase in DP results in: increase in (1) mechanical properties, (2) melting temperature, and (3) mechanical strength, (4) viscosity

26
Q

What is conformation?

A

Arrangement due to the rotation about single bonds

27
Q

Types of sequence isomerism / positional isomerism (?)

A

1) Head to tail, 2) Head to Head, 3) Tail to tail

28
Q

Types of stereoisomerism (w respect to spatial arrangment)

A

Isotactic, syndiotactic, atactic

29
Q

Types of structural isomerism (or geometrical isomerism?)

A

Cis, trans

30
Q

Refers to those with repeat units having a double bond between chain carbon atoms

A

Geometrical isomers

31
Q

Types of molecular structure

A

Linear, branched, cross-linked, network

32
Q

Factors for crystallinity

A

Rate of cooling, molecular chemistry, and chain configuration

33
Q

Many bulk polymers that are crystalized from a melt are semicrystalline and form
a [—] structure.

A

Spherulite

34
Q

A spherulite structure is formed when….

A

Bulk polymers that are crystalized from a melt ends up semicrystalline

35
Q

Faster rate of cooling (inc/dec.) chance for crystallinity

A

Decrease

36
Q

Irregularity in structure (inc/dec.) chance for crystallinity

A

Decrease

37
Q

It can be said that cis forms are (rubbery/crystalline) while trans are (rubbery/crystalline).

A

Cirs - rubbery ; trans - crystalline

38
Q

(Less/more) flexible chains are more susceptible to thermal agitation.

A

More flexible chains

39
Q

A material that can increase the distance between adjacent polymer chains making it easier for them to move about.

A

Plasticizers

40
Q

Polarity (inc./dec.) bonding between chains

A

Increases

41
Q

Morphology of crystalline polymers depend on 3 factors…

A

Solvent medium, Temperature, Cooling Rate

42
Q

Conformations of polymers (or polyethylene crystals)

A

Planar zigzag, helical, orthorombic, triclinic, monoclinic

43
Q

If there is steric hindrance, the preferred conformations of polymers is…

A

Helical

MatE 21 (7 decks)

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