Chemistry Question

Hello,

Ineed a hand on writing a essay about representative polymer (polyurethane)

Pre-approved topics:
• replacements for polycarbonate of bisphenol A (PCBPA)
• ultrahydrophobic polymers
• rigid spray foams for insulation
• biodegradable polymers
• biocompatible polymers
• self-repairing polymers
• dendrimers
• OLEDs and conducting polymers
• thin films: adhesives, inks, paints, cosmetics, etc.
• photoresists and computer chip microlithography
• polymers and nanocomposites in sports equipment
Select a category from the list above and then choose a representative polymer (or two). In your
paper, include the monomer and polymer structures. Discuss how the polymer is made, including
the synthesis or mechanism. Discuss the physical properties of the material; how would it be
classified? What are the applications? In short, in your paper, I want to see as much CHEMISTRY as
possible: try to make connections between your topic and the concepts in the course. Really, this is
your chance to “show off” what you’ve learned this semester!
Some guidelines:
•
•
•
•
•
Your paper (doubled-spaced) should be no shorter than 5 pages and no longer than 10 pages.
I won’t put a “word count” requirement, because you’re mature enough now to not need
that nonsense! Really, if you’re doing a good job, then 6 – 8 pages should work fine.
Please illustrate your paper with images or schemes – just don’t go overboard! All figures
should have descriptive captions and be properly explained in the text.
Be reasonable with your formatting choices: use a legible font (12 pt is good), decent
margins (2 cm all around is fine), and double-spacing.
Cite appropriately. You can use the ACS citation style.
Get someone to proofread your paper – your writing should be as professional as possible.
Also, make sure any symbols/equations etc. print out correctly so that it isn’t confusing.
• in this chapter:
– structure and composition
– properties
– nomenclature
• later chapters:
– polymerization mechanisms
– applications
– degradation
CHM4155
Introduction to Polymer Chemistry
2
• made of many repeating units
• prepared from monomers
CH2
n
n CH2 = CH2
polymerization
Polymethylene or polyethylene?
CHM4155
Introduction to Polymer Chemistry
CH2-CH2
n
repeating unit
3
CH2-CH2
n
structural
polymethylene
source or derivative
polyethylene
CHM4155
Introduction to Polymer Chemistry
4
Abbreviation
Full Name
Abbreviation
Full Name
PE*
Polyethylene
PMMA*
Polymethyl Methacrylate
HDPE*
High Density Polyethylene
PPO
Polyphenylene Oxide
LDPE*
Low Density Polyethylene
PES
Polyethersulfone
PP*
Polypropylene
PBT
Polybutylene Terephthalate
PS*
Polystyrene
PPS
Polyphenylene Sulfide
CA
Cellulose Acetate
PETE* (or PET)
Polyethylene Terephthalate
PVC* (or V)
Polyvinyl Chloride
PEEK
Polyether ether ketone
RPVC
Rigid Polyvinyl Chloride
TPU
Thermoplastic Polyurethane
SPVC
Soft Polyvinyl Chloride
PDMS*
Polydimethyl Siloxane
ABS
Acrylonitrile-Butadiene-Styrene
PTFE*
Polytetrafluoroethylene
POM
Polyoxymethylene (aka
Polyformaldehyde)
CHM4155
Introduction to Polymer Chemistry
5
• Polymers can be classified by:
– shape
– application
– mechanism of polymerization
– polymerization process
– thermoplastic/thermoset polymers
CHM4155
Introduction to Polymer Chemistry
6
1. Linear
1) Linear
2. Branched
2) Branched
3. Network
3) Network
crosslinked
CHM4155
Introduction to Polymer Chemistry
7
+
N
N
• f = 1 à dimer
=
N
+
N
N
N
• f = 2 à linear polymer
=
N
N
N
CHM4155
+
N
N
N
• f = 3 à branched polymer
=
Introduction to Polymer Chemistry
8
• homopolymer:
-A-A-A-A-A-A-A-A-
• alternating copolymer: – A – B – A – B – A – B – A – B • random copolymer:
-A-A-B-A-B-B-B-A-B-A
• block copolymer:
-A-A-A-A-A-B-B-B-B-
CHM4155
Introduction to Polymer Chemistry
9
isotactic
= identical stereochemistry
n
H 2C
CH
CH3
Me
Me
Me
Me
Me
Me
R
R
R
R
R
R
syndiotactic
= alternating stereochemistry
Me
Me
Me
Me
Me
Me
R
S
R
S
R
S
Me
Me
Me
Me
Me
Me
R
S
S
R
R
S
atactic
= random stereochemistry
CHM4155
Introduction to Polymer Chemistry
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The three images below represent the three possible
tacticities of polypropylene. Which is syndiotactic PP?
1.
2.
3.
4. I’m not sure
CHM4555
Introduction aux polymères
11
BRANCHED
LINEAR
A
A
A
A
A
A
CHM4155
A
A
A
A
A
A
A
A
Introduction to Polymer Chemistry
A
A
A
A
A
A
A
12
• Graft copolymers: a special kind of block
copolymers
A
A
A
A
C
B
CHM4155
A
B
A
B
A
B
A
B
Introduction to Polymer Chemistry
A
B
A
B
A
B
B
13
• Polymer properties are strongly affected by the
way the monomer units are interconnected
INTERMOLECULAR FORCES
BETWEEN POLYMER CHAINS !
CHM4155
Introduction to Polymer Chemistry
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• Non-crosslinked = polymer molecules can slide
across one another
• Crosslinked = polymer molecules are
permanently bonded together
CHM4155
Introduction to Polymer Chemistry
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Comb
comb
Comb
Comb
Comb
Star
star
Star
Star
Star
Ladder
Ladder
ladder
Ladder
Ladder
CHM4155
Semiladder
Semiladder
semi-ladder
Semiladder
Semiladder
Introduction to Polymer Chemistry
16
• Adhesives
• Plastics
• Fibers
• Coatings
• Rubbers (or elastomers)
• etc…
CHM4155
Introduction to Polymer Chemistry
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Functionality
Snapshot during
reaction
CHM4155
CHAIN
STEP
free radicals
reactive groups
completed polymers
oligomers
unreacted monomer
rapidly consumed
monomer
a few growing radicals
no radicals
Introduction to Polymer Chemistry
18
A!
B!
INITIATION
CHM4155
C!
1ST ADDITION
D!
GROWTH
Introduction to Polymer Chemistry
E!
TERMINATION
19
A!
B!
OLIGOMERIZATON
GROWTH
C!
TERMINATION
« living polymerization »
CHM4155
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20
Monomer concentration
STEP growth
CHAIN growth
0
Time
CHM4155
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IN
A
CH
MM
STEP
MM
MM
Which graph best represents the rate of polymer MM
growth for chain and step reactions?
EP
T
S
IN
A
CH
time
1.
IN
A
CH
EP
T
S
time
2.
time
3.
4. I’m not sure
CHM4155
Introduction to Polymer Chemistry
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n
n
polystyrene
styrene
O
O
HO-C-(CH2)4-C-OH + H2N-(CH2)6-NH2
adipic acid
CHM4155
-H2O
O
O
C (CH2)4 C NH (CH2)6 NH
hexamethylenediamine
Introduction to Polymer Chemistry
n
nylon-66
23
1. bulk
2. solution
3. suspension
4. emulsion
CHM4155
Introduction to Polymer Chemistry
24
Method
Advantages
Disadvantages
Bulk
simple
no contaminants
heat control
high viscosity
Solution
better heat dissipation
low viscosity
must buy/remove/dispose
of solvent
possible chain transfer
Suspension
Solution +
solvent = water
polymer in bead form
remove water
possible agglomerization
Emulsion
Suspension +
high MW possible
must remove water and
emulsifier
CHM4155
Introduction to Polymer Chemistry
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Initiator
liquid
monomer
CHM4155
Introduction to Polymer Chemistry
26
Initiator
Monomer
solvent
(organic)
CHM4155
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27
Initiator
Monomer
solvent = water
CHM4155
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28
Monomer
Initiator
P
P
P
“micellar water”
CHM4155
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29
Thermoplastic:
• linear and branched polymers
• chains can flow
Thermoset:
• heavily cross-linked (network) polymers
• chains can’t flow
CHM4155
Introduction to Polymer Chemistry
30
O
HO C
O
C OH
+
HO
OH
-H2O
O
C
terephthalic acid
CHM4155
O
C O CH2CH2 O
n
PET
Introduction to Polymer Chemistry
31
S
S8
n
n
monomer
S
polymer
S
S
S
S
n
crosslinked polymer
put in mold
added as
crosslinking agent
thermoset polymer
CHM4155
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Thermoplastic:
• linear and branched polymers
• dissolve (in appropriate solvent)
• melt when heated
Thermoset:
• heavily cross-linked (network) polymers
• do NOT dissolve
• do NOT melt when heated
CHM4155
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• linear polystyrene:
PS
Ph
Ph
Ph
Ph
Ph
Ph
Ph
• cross-linked polyurethane
O
N
H
O
N
N
PU
O
H
N
O
N
N
H
N
H
N
O
O
CHM4155
Introduction to Polymer Chemistry
34
n
HO
O
HO
O
n
acrylic acid
poly(acrylic acid) or PAA
• non-crosslinked form
→ thermoplastic → readily dissolves in water
• heavily crosslinked
→ network polymer → thermoset → insoluble in water
• only slightly crosslinked
→ something different → absorbs the water and swells
CHM4155
Introduction to Polymer Chemistry
35
• “like dissolves like”
• septa = slightly crosslinked polybutadiene
• solvents = water vs. toluene
n
CHM4155
Introduction to Polymer Chemistry
36
•
•
•
•
•
•
•
•
•
degree of polymerization
molar mass
crystallinity
density
thermal properties
mechanical properties
coefficient of restitution
flammability
degradability
CHM4155
Introduction to Polymer Chemistry
37
• DP = average number of repeating units of
all molecules present
• molecular weight will be proportional to
DP (or DP + 2)
CHM4155
Introduction to Polymer Chemistry
38
1. Number average molecular mass
2. Weight average molecular mass
Typical molecular masses = 104 to 106 Da
CHM4155
Introduction to Polymer Chemistry
39
is the most intuitive interpretation of polymer
M n molecular mass
can be thought of as the mathematical mean of the
M w masses of all the different chains, where the
heavier polymer chains ‘count for more’ in the
calculation. The value is therefore skewed
towards the heavier chains in the weight average
molecular mass.
CHM4155
Introduction to Polymer Chemistry
40
1. Number average molecular mass
∑ M i Ni
w
Mn =
= i
∑ Ni ∑ Ni
i
i
€
CHM4155
Introduction to Polymer Chemistry
41
∑M N
M =
∑N
i
n
50
Mn
40
30
20
10
i
i
0
1×10
i
€
Number of chains
Number average
molecular mass
i
4
4
4
€
[(104 )(10)]+ [(2×104 )(20)]+ [(3×104 )(50)]+ [(4 ×104 )(10)]+ [(5×104 )(10)]
Mn =
10+ 20+ 50+10+10
€
Mn =
€
CHM4155
4
2×10
3×10
4×10
Molecular Weight (Da)
4
5×10
2,900,000
= 2.9×10 4 Da
100
Introduction to Polymer Chemistry
42
2. Weight average molecular mass
2
i
∑ wi M i ∑ M Ni
Mw = i
∑ wi
i
= i
∑ M i Ni
i
€
CHM4155
Introduction to Polymer Chemistry
43
∑M N
M =
∑M N
w
€
€
€
€
2
i
i
i
i
50
Mw
Number of chains
Weight average
molecular mass
40
30
20
10
i
0
1×10
4
i
4
4
4
2×10
3×10
4×10
Molecular Weight (Da)
4
5×10
[(104 )2 (10)]+ [(2×104 )2 (20)]+ [(3×104 )2 (50)]+ [(4 ×104 )2 (10)]+ [(5×104 )2 (10)]
Mw =
[(104 )(10)]+ [(2×104 )(20)]+ [(3×104 )(50)]+ [(4 ×104 )(10)]+ [(5×104 )(10)]
9,5 ×1010
4
Mw =
=
3.3×10
Da
6
2,9 ×10
CHM4155
Compare to
Introduction to Polymer Chemistry
€
M n = 2.9×10 4 Da
44
• Mw/Mn ratio = polydispersity index
• reflects the distribution of molecular masses
CHM4155
Introduction to Polymer Chemistry
45
Absorbance
CHM4155
Molecular weight
low polydispersity
high polydispersity
Mw / Mn low
Mw / Mn high
Introduction to Polymer Chemistry
Molecular weight
46
Crystallinity
Crystallinity
Crystallinity
Amorphous
Amorphous
Amorphous
Crystalline
Crystalline
Crystalline
Interchain
Interchain
Interchaininteractions
Interactions
interactions
weak and/or
forcesbulky
Weak forces
Weak forces
and/or bulky
and/or
side
groups
side groups
bulky side groups
strong
forces
Strong
forces,
no steric
Strong and/or
forces, no steric
hinderance
hinderance
no steric hindrance
Solid state
poor packing
good packing
Appearance
Appearance
Appearance
CHM4155
Introduction to Polymer Chemistry
47
Rank the following three polymers in increasing order of
close-packing (worst à best) in the solid phase:
1.
2.
3.
4.
5.
6.
ABC
ACB
BAC
BCA
CAB
CBA
CHM4155
H
N
A=
O
H
N
O
H
N
O
H
N
O
B=
C=
Introduction to Polymer Chemistry
48
• general range: 0.85 to 2.5 g/cm3
• can be:
– reduced (down to 0.01 g/cm3) by using foaming
additives
– increased (up to 3.5 g/cm3) by using filled polymers
• in comparison:
– density of aluminum = 2.7 g/cm3
– density of stainless steel = 7.9 g/cm3
CHM4155
Introduction to Polymer Chemistry
49
• The most important parameter – Tg
– glass transition temperature
– point where the polymer material changes
from a glassy solid to softer, more flexible
plastic
– ~ mp for polymers
CHM4155
Introduction to Polymer Chemistry
50
TEMP INCREASING
Tg
Glassy
State
amorphous
polymer
Tg
crystalline
polymer
Rubbery
State
Gum-like
State
Flexible
Thermoplastic
Tm
Viscous
Liquid
State
rubber ducky…
CHM4155
Introduction to Polymer Chemistry
51
Pol y m e r
Approx. Tg
(°C)
Approx. Tm
(°C)
Low density polyethylene
– 125
137
Natural rubber (polyisoprene)
– 73
28
Syndiotactic polypropylene
– 8
176
Poly(ethylene terephthalat e )
61
270
Poly(vinyl chloride)
81
273
Isotactic polysty r e n e
100
250
Atactic poly(methyl
methacrylat e )
105
200
CHM4155
Introduction to Polymer Chemistry
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If we need a polymer that is ALWAYS PLIABLE at room
temperature, Tg should be ____________.
If we need a polymer that is ALWAYS RIGID at room
temperature, Tg should be ____________.
1. > 20ºC, >20ºC
2.
600>
600>
210
120
450
330
90
60
210
180
120
60
270
210
600>
600>
600>
600>
210
120
420
330
90
60
240
210
90
60
270
240
600>
600>
600>
600>
270
210
510
450
90
90
240
210
120
90
300
270
600>
600>
600>
600>
300
270
600>
510
90
90
240
210
120
120
300
270
600>
600>
600>
600>
210
120
420
330
90
60
210
180
90
60
270
210
600>
600>
600>
600>
Small
Large
PIR
Small
Large
SPU
Small
Large
PF
Small
Large
1.8 m
4.8 m
1.8 m
4.8 m
1.8 m
4.8 m
1.8 m
4.8 m
1.8 m
4.8 m
1.8 m
4.8 m
1.8 m
4.8 m
1.8 m
4.8 m
7
Environmental Pollution 312 (2022) 120067
S. Wi et al.
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m, as an upward airflow generated owing to buoyancy due to the heat
generated by the fire.
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Credit author statement
Seunghwan Wi: Writing – review & editing, Visualization, Sung­
woong Yang: Formal analysis, Resources, Beom Yeol Yun: Methodol­
ogy, Investigation, Yujin Kang: Methodology, Resources, Sumin Kim:
Conceptualization, Supervision.
Declaration of competing interest
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
the work reported in this paper.
Data availability
Data will be made available on request.
Acknowledgments
Funding: This work was supported by the Korea Agency for Infra­
structure Technology Advancement (KAIA) grant funded by the Ministry
of Land, Infrastructure and Transport [grant number 22CTAP-C16377702].
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://doi.
org/10.1016/j.envpol.2022.120067.
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Mechanics of Composite Materials, Vol. 38, No. 3, 2002
PHYSICOMECHANICAL CHARACTERISTICS
OF SPRAY-ON RIGID POLYURETHANE FOAMS
AT NORMAL AND LOW TEMPERATURES
V. A. Yakushin, N. P. Zhmud’,
and U. K. Stirna
Keywords: spray-on polyurethane foam, processing factors, physicomechanical characteristics, structure,
low temperature
The effect of processing factors on the inhomogeneity and physicomechanical characteristics of spray-on polyurethane foams is studied. The dependences of the basic characteristics of foam plastics on the apparent density and cell-shape factor are determined. A method is offered for evaluating the effect of the technological
surface skin on the tensile characteristics of foam plastics under normal and low temperatures.
The cryogenic insulation of large-size tanks is usually made of a spray-on rigid foam polyurethane (FPU). Such FPUs
must possess an appropriate complex of thermophysical and mechanical characteristics providing reliable operation of the insulation in service conditions, namely under periodic freezing and thawing the tank upon its filling and emptying. Any through crack
appearing in the insulation during this process can become a center of condensation of the surrounding vapors and gases on the
cooled surface of the article, whose intense evaporation upon heating of the tank can cause local cracking of the insulation.
As is well known, the properties of foam plastics are determined by the properties and amount of the polymer base and
gases filling its cells and by the morphology of its cellular structure [1-3]. As already shown by different theoretical models and
numerous experiments, essential are not only the integral characteristics (the apparent density, the degree of closure of cells,
etc.), but also the structural morphology of foams, namely the amount of the polymer in the rods, nodes, and walls of cells, their
geometrical sizes, cell- and rod-shape factors, etc. [4-9]. In addition, the properties of a foam plastic are considerably affected
by the polydispersity and inhomogeneity of its structure in the bulk [10-12]. All these factors, in turn, greatly depend on the processing parameters of foam plastics.
In experimental estimation of the effect of most of the indicated factors on the properties of foam plastics, the properties of filling foams are usually investigated. The test specimens are prepared by the method of free foaming, since such a technology, as a rule, yields a foam plastic with a most homogeneous structure. The effect of various factors on the inhomogeneity
of the structure and properties of foam plastics has been investigated to a much lesser extent, and most of these studies deal with
the so-called integral foams [3, 13]. They are called so because, upon their manufacture, a layer of high density is formed on the
Latvian State Institute of Wood Chemistry, Riga, LV-1006, Latvia. Translated from Mekhanika Kompozitnykh
Materialov, Vol. 38, No. 3, pp. 417-426, May-June, 2002. Original article submitted January 26, 2001; revision submitted September 18, 2001.
0191-5665/02/3803-0273$27.00 © 2002 Plenum Publishing Corporation
273
article surface, which in some cases approaches the density of the unfoamed polymer. This layer is called the surface skin or the
integral layer.
Although the spray-on FPUs are in general similar to the well-investigated filling foam plastics, they have some important distinctions. First, the initial compositions are catalytically more active and the processes of foaming and curing of a
foam plastic and accordingly the formation of its macro- and microstructures proceed at a higher rate. Second, as a rule, their
structure in the bulk is more nonuniform. In addition, upon spraying, a surface skin is formed on the surface to be insulated,
whose properties differ significantly from those of the foam plastic in the bulk. The fact that exactly this skin takes up the basic
loads during the operation process of the insulated articles is of fundamental importance.
The contribution of the surface skin to the load-carrying capacity of foam-plastic articles has been really estimated
only with the example of integral foam plastics, for which special testing methods, similar to those for sandwich beams, have
been developed. However, these methods are not suitable for spray-on foam plastics, because the latter have no such a symmetric structure, since the dense surface skin forms only on one side (on the surface to be insulated).
The purpose of this study is to investigate the effect of basic processing factors on the inhomogeneity of the structure
and physicomechanical characteristics of spray-on FPUs at normal and low temperatures. We investigated the properties of the
foam plastics both in the core of sprayed-on plates and in the surface skin. We considered a spray-on variant of a polyurethane
composition based on a blend of polyethers and polyesters [14] and containing 12% a fire retardant — trichloroethyl phosphate.
To raise the catalytic activity, the composition was additionally doped with an amine catalytic agent (dimethylethanolamine) in
amount of 2 to 6% of the total mass of the polyether/polyester blend. In all the cases, the ratio of the components during spraying was maintained constant and corresponding to the ratio of the contents of functional groups NCO/OH = 1.2.
The spraying of foam-plastic plates was performed on a universal “Cannon” machine (Italy) having a capacity of 6
l/min. Horizontally located 6 mm thick sheets of an AMG-6 aluminum alloy covered with a separating lubricant ser…