Transcript Polycondensation Processes Step

General Approaches to Polymer
Synthesis
• 1. Addition
Chain Growth
Polymerization of Vinyl Monomers
Ring Opening Polymerization
Heterocylics
Metathesis of Cyclic Olefins
2.
3.
Condensation
Step Growth
Polymerization of A-B or AA/BB Monomers
Modification of Preformed Polymers
Polysaccharides
Peptides and Proteins
Synthetic Precursors
Major Developments in the 1950-60's
Living Polymerization (Anionic)
• Mw/Mn  1
• Blocks, telechelics and stars available
(Controlled molecular architecture)
• Statistical Stereochemical Control
• Statistical Compositions and
Sequences
• Severe functional group restrictions
Ziegler-Natta (Metal-Coordinated)
Polymerization
•
•
•
•
Stereochemical Control
Polydisperse products
Statistical Compositions and Sequences
Limited set of useful monomers, i.e. olefins
• SINGLE SITE CATALYSTS
Additional Developments in the 1980's
•
"Immortal" Polymerization (Cationic)
–
–
–
–
–
Mw/Mn  1.05
Blocks, telechelics, stars
(Controlled molecular architecture)
Statistical Compositions and Sequences
Severe functional group restrictions
Free Radical Initiated Polymerization
• Controlled Free Radical
Polymerization
• Broad range of monomers available
• Accurate control of molecular weight
• Mw/Mn  1.05 --Almost monodisperse
• Blocks, telechelics, stars
• (Controlled molecular architecture)
• Statistical Compositions and Sequences
Current Strategies in Polymer Synthesis
• Objectives: Precise Macromolecular Design
• 1
–
–
–
–
. Control of: Molecular Weight
Molecular Weight Distribution
Composition
Sequence of repeat units
Stereochemistry
• 2. Versatility
–
Genetic Approaches via Modified
Microorganisms
•
•
•
•
•
Monodisperse in MW
Monodisperse in Composition
Sequentially Uniform
Stereochemically Pure
Diverse set of functional groups possible
through synthesis of novel amino acids
Step-Growth or Condensation Polymerizations
Molecular Weight predicted by Carothers Equation:
A-A + B-B
-[A-B-]x + x C
[A-A] = [B-B] = No
# of functional groups remaining at anytime = N
Extent of reaction = p
No - N
p = _____ or N = No (1 - p)
No
Degree of Polymerization, D.P. = No / N = 1 / (1 - p)
Problems in Achieving High D. P.
1. Non-equivalence of functional groups
a. Monomer impurities
1. Inert impurities (adjust stoichiometry)
2. Monofunctional units terminate chain
b. Loss of end groups by degradation
c. Loss of end groups by side reactions with media
d. Physical losses
e. Non-equivalent reactivity
f. Cyclization
.
Unfavorable Equilibrium Constant
Impact of percent reaction, p, on DP
Degree of Polymerization, D.P. = No / N = 1 / (1 - p)
Assuming perfect
stoichiometry
if p =
0.5
DP =
2
0.7
0.9
0.95
3.3
10
20
0.99
0.999
100
1000
DPmax= (1 + r) / (1 - r) where r
molar ratio of reactants
if r = [Diacid] / [diol] = 0.99, then
DPmax= 199
Cyclization
1. Thermodynamic stability
Rings of: 3,4,8 < 11 < 7, 12 << 5 << 6
2. Kinetic Control
Propagation more rapid than cyclization
Reduce probability of collision for rings 12
Non-reversible propagation process
Equilibrium in Polyesterification
Reaction in closed system
OH
OH
+
O
O
Keq =
Keq =
O
[-COO-] [H2O]
[COOH] [OH]
p2
(1-p)2
p = fraction esterified
DP = 1/(1-p)
=
+
H2O
(p [M]o)2
([M]o - p([M]o)2
p=
K1/2
1-K1/2
1/2
DP = 1 + K
Equilibrium in Polyesterification
Effect of Keq on extent of reaction and DP
1/2
DP = 1 + K
transesterification
esterification
amide formation
Keq
p
Xn
0.01
0.1
1.11
1
0.5
2
16
0.8
5
81
0.9
10
361
0.95
20
9800
0.99
100
39,600
0.995
200
Driving reaction to completion in open,
driven system
Keq
DP
[H2O]
1
2
20
50
100
2.5
0.0132
0.00204
0.000505
200
5
20
0.000126
4.0
0.211
50
100
200
0.0327
0.0081
0.00201
16
Types of Condensation Reactions
1. Polyesters
O
HO R OH
+
- n CH3OH
O
+
H3CO
O
R O
OH
O
O
*
R'
HO
HO R OH
O
- n H2O
O
*
R'
R'
O
O
O
R O
R'
OCH3
O
H2O
HO
trace
*
n
O
O
-n H2O
(CH2)5 C OH
(CH2)5 C O
-n H2O
HO R OH +
O
O
O
O
O
HO R O
O
OH
*
O
R O
O
O
*
n
*
n
Preparation of Aromatic Polyesters
O
H3C O C
O
C O CH3
Dimethyl Terephthalate (DMT)
O
H O C
Terephthalic Acid
+ CH3OH
xs
HO-CH2CH2-OH
CH2OH
O
C O
CH2
CH2OH
O
C O H
O
O C
CH2
O
O C
O
C O
CH2
1 mm Hg
280 C
CH2
CH2OH
O
O C
O
C O
SbO3 or Ti(OR)4
CH2
CH2O
CH2OH
+ HOCH2CH2OH
Stoichiometry and DP controlled by extent of glycol removed.
Types of Condensation Reactions
2. Polyamides
O
H2N R NH2 +
H2N R NH2 +
- n HCl
O
*
R'
Cl
H2N
H
R N
O
R'
(CH2)5 C OH
-n H2O
N *
H n
O
O
R'
Cl
O
H2O
trace
O
OH
O
NH
H
R N
*
R'
HO
O
- n H2O
O
O
(CH2)5 C N
H
N *
H n
Polyamides via Condensation -- Nylon 66
O
H O
O C-(CH2)4-C O
H
+
NH2 CH2-(CH2)4-CH2 NH2
O
O
C-(CH2)4-C
OONH3+
NH3+
CH2
CH2
(CH2)4
slight excess
Nylon Salt
60% Slurry
200 C, 15 Atm. 1 hr
O
O
NH3+(CH2)6-NH-C-(CH2)4-C-NH-(CH2)6-NH-C-(CH2)4-C O
8-10
O
O
mp. 265C, Tg 50C,
MW 12-15,000
Unoriented elongation
780%
270-300 C, 1hr
-
H2O
O
NH-(CH2)6-NH-C-(CH2)4-C
O
Nylon
6
6
Types of Condensation Polymers
O
O
O
R O C R' C O
Polyesters
n
R' C O C
Polyanhydrides
O
O
O
O
O
Polycarbonates
O
n
R
Polyacetals
n
n
Lexan Polycarbonate
Interfacial Process
O
Na+
-O
Na+
CH3 CH3
+
Cl-C-Cl
O
Tm = 270C,
CHCl2
O
C
Tg = 145-150C
10-40 % Crystalline,
Brittle Temp. - 10C
Ester Interchange
O
Aq NaOH
CH3 CH3
x
Lexan
OH
C
1) 200 C/20mm
O
+
Lexan +
2) 300 C. <1mm
O
H
CH3 CH3
+ NaCl
O
O
H
O
O
No Solvent, Pure Polymer with MW > 30,000
Formed
Types of Condensation Polymers
R O
H
N R' N
C
H
O
CH3
O
O
O
CH3
polyurethanes
polyphenylene oxide
O
Ar
O
R
S
polyarylenes
O
O
polyarylene ether sulfones
Low Temperature Condensation Polymerization
• Interfacial or Solution in Polar Aprotic Solvents
Parameter
Low Temp
High Temp
Moderate
Not Essential
Not Essential
Highly
Reactive
High
High
Essential
Essential
Thermally
stable
Moderate
Intermediates
Purity
Stoichiometry
Heat Stability
Structure
Cost
Interfacial or Solution Polymerization in
Polar Aprotic Solvents (Con’t)
Conditions
Low Temp
High Temp
Time
Temperature
Pressure
Yield
By-products
Solvents
Minutes to hours
0 – 150 C
Atmospheric
Low to moderate
Salts
Required
Hours to days
>250 C
High to vacuum
Quantitative
Volatiles
None
Applications of Low Temperature Condensations
• Prep. of Infusible Thermally Stable Polymers
• Prep. of Thermally Unstable Polymers
Prep. of Polymers Containing Functional Groups with
Differing Reactivity
Formation of Block or Ordered Polymers
(No equilibration of polymer in melt allowed)
Direct Production of Polymer Solutions for Coatings,
Spinning into Fibers, Solvent Blending to form
Composites
Types of Condensation Polymers
O
O
O
O
H
R N C R' C N
H
N
N
O
polyamides
O
polyimides
O
O
S
S
Ar
N
N
polybenzoxazoles
Ar
N
N
polybenzthiazoles
Aromatic Polyamides “Aramids”
C-Cl
NH2
O
+
NH2
O
M-isomers favor formation of
soluble polymers
C-Cl
Unique solvent combination
DMF, LiCl
S
O O
O
C-NH
O
NH-C
O
C-NH
C-NH
Nomex
O
NH-C
O
M.p. > 350 C
Can be Dry Spun to Fiber
As Spun:
Elongation, 23-34%,
Tenacity, 4.6-5.3 g/Denier
70% Strength Retained in Ionizing
Radiation
Polyimides for Electronic Applications
O
O
O
2 (CH3)2CHOH
HO-C
O
O
O
PMDA
O
C-O
O-C
O
C-Cl
C-OH
O
syn and anti isomers
Cl-C-C-Cl
O
Cl-C
C-O
O-C
O
O
O
O
O
NH2
O
O
DMAC
ODA
NH2
O
O
NH-C
C-O
O-C
O
C-NH
O
O
Fabricate in soluble form
soluble
O
heat or
O
N
N
O
O
insoluble
Kevlar
amine catalyst
O
Post treat to final form
POLYETHERSULFONES
K2CO3
HO
Bis-Phenol-A
K+-O
Bis-nucleophile
O- K+
OH
K+-O
+
-
O
S
Cl
O
Polymerize by SnAr2
+
O K
DMSO/Toluene
160 C
2) CH Cl
3
CH3O
O
O
S
O
Cl
Monofunctional terminator to
stabilize polymer
Use Temperature 100 to + 175C
Stable in air to 500C,
Self Extinguishing
Molecular Weight = 65,000 - 250,000
Amorphous Material, Tg  200C, Films pressed at 280C
Polyphenylene Oxide (PPO)
Oxidative Coupling Process
R1
R1
OH
+
n/2 O 2
R1
O
O
cat
R2
R2
R2
+ n H 2O
cat =
or
N
10:1
CH3
N
CH3
CH3
N
CH3
Cu +
Amine Complex
3 :1
Noryl is a blend with polystyrene
Mn 30,000 to 120,000
Amorphous , Tg  210C
Crystalline, Tm  270C
Brittle point
 -170C
Thermally Stable to  370C
Noryl is Unique Blend
•
•
•
•
Single Phase, Tg dependent upon composition
Maximum tensile strength at 80 wt% PPO
Other properties; volume fraction weighted average
Blend compatible with rubber modified polystyrene (high impact
resistance)
• Applications of Noryl Engineering Thermoplastics
•
Useful properties
•
High impact resistance
•
Flame retardant
•
High chemical stability
•
Low moisture absorbance (0.07%0
•
Use in appliance housings
•
Automobile dashboards
•
Radomes, fuse boxes, wiring splice devises