synthesis and characterization of cellulose derivatives for water repellent properties sechin chang...
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Synthesis and Characterization of Cellulose Derivatives for Water
Repellent Properties
SeChin Chang and Brian Condon
Cotton Chemistry and Utilization Research UnitUSDA-ARS-Southern Regional Research Center, New Orleans, LA
Cotton Chemistry & Utilization Research Southern Regional Research Center
Beltwide Cotton Conference, January 11, 2007, New Orleans
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
NH2
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
1-step
2, Nitro-benzyl cotton and cellulose
NO2
3, Amino-benzyl cotton and cellulose
Mission of CRIS 6435-41000-094-00D
CRIS (Current Research Information Service)
Our CRIS is on Value Added Products and Processes from Cotton involves increasing cotton’s consumption by inventing products and processes that demonstrate preferred use of cotton over competing
fibers in needed and emerging applications
Talk Outline
• Design Criteria
• Synthesis – Nitro-benzylated (NB) cotton and cellulose– Amino-benzylated (AB) cotton and cellulose
• Characterization– Nitro-benzylated cotton and cellulose
• FT-IR spectroscopy• TGA• CP-MAS carbon-13 NMR
– Amino-benzylated cotton and cellulose • FT-IR spectroscopy• TGA• CP-MAS carbon-13 NMR
• Curing properties with Bis-phenol-A-di-glycidyl-ether (BADGE)• Conclusions
Design criteria
• Water repellency, reactivity with epoxide and isocyanates, and the ability to complex main group and transition metals; • Potential uses: adhesives, powder coatings, and composites• Method of cellulose modification:
– Synthesis nitro-benzylcellulose (cotton or microcrystalline);– Reduced nitro-group to amine [heterogeneous reduction in ethanol]; or– Substitute nitro-group on aryl ring to H, S-, C-, P- and other groups
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
X
OO O
OH
OH
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
2-steps
cellulose 1, Mw = 182,0002, X = NO2 = nitro-benzyl-cellulose3, X = NH2 = amino-benzyl-cellulose
Synthesis of nitro-benzyl (NB) cotton & cellulose
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
NO2
OO O
OH
OH
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
1-step
cellulose 1, Mw = 182,000 2, Nitro-benzyl cotton and cellulose
• Cellulose was subjected to a solvent exchange. • Prepared solution of 2.5g Cellulose, 7g LiCl, and ~100ml DMAc• Added 1.88g DMAP and 10.6g of 4-nitrobenzyl chloride• Heated to 80ºC for 6h under Nitrogen • Work up included: cooling, washing with water• Obtained a brown powder in 70-78% yield
• Modified Lit. Method of: N. Joly, R. Granet and P. Krausz, Journal of Carbohydrate Chemistry, Vol. 22, No.1, 47, 2003
FT-IR of cellulose and NB cellulose
OO O
OH
OH
HO O
OH
O
OHOHHO
OHHO
OHHO
n
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
NO2
Synthesis of amino-benzyl (AB) cotton & cellulose
• Suspended 1.0g of Nitro-benzyl cotton or cellulose treated with
– 50ml EtOH, 2g Indium metal and saturated ammonium chloride solution 5.0 ml
• Heated to 90ºC, overnight, under nitrogen
• Work up included: cooling, dilution with water, decanting, washing with water and ether, and drying in vacuo at 40ºC
• Obtained a light brown powder in 90-95% yields.
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
NH2
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
1-step
2, Nitro-benzyl cotton and cellulose
NO2
3, Amino-benzyl cotton and cellulose
• Modified Lit. Method of: Pitts, M.R., Harrison, J.R., and Moody, C.J. J. Chem. Soc., Perkin Trans, 1, 2001, 955-977
OO O
OH
OH
HO O
OH
O
OHOHHO
OHHO
OHHO
n
FT-IR data of NB & AB cellulose
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
NO2
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
NH2
IR Spectral Interpretation
• In the IR spectrum of nitro-benzylcellulose, some peaks for acetone addition oligomers may be present.
However, upon reduction of aryl-nitro to amine-group, the other side products were removed.
Cellulose NB Cellulose NB Cotton AB Cellulose AB Cotton
OH stretch 3320 cm-1
(broad)3357 cm-1
(broad)3345 cm-1
(broad)Overlap (broad)
Overlap (broad)
C-H stretch 2895 cm-1 2920 cm-1 2901 cm-1 Overlap ~2900 cm-1
C-O stretch ~1180 cm-1 1170 cm-1 and 1019cm-1
1159 cm-1 and 1016 cm-1
1155 cm-1 1159 cm-1 and 1017 cm-1
C-O-C Bend & OH Bend
1103 cm-1 and 1026 cm-1
1105 cm-1 and 1020 cm-1
Overlap ~1060 cm-1 Overlap (broad)
N=(O)2 asymmetric
1593 cm-1 and 1504 cm-1
1603 cm-1 and 1509 cm-1
N=(O)2 symmetric
1335 cm-1 1341 cm-1
C-N stretch for aromatic
851 cm-1 850 cm-1 835 cm-1 828cm-1
N-H bend stretch
1609 cm-1 and 1516 cm-1
1606 cm-1 and 1514 cm-1
N-H stretch 3221 cm-1 and 3121 cm-1
3222 cm-1
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
NO2
123
4 56
C6
C3, C2, C5
C4C1
NB-cotton
NB-cellulose
13C CP/MAS NMR of NB cotton & NB cellulose
~106 ~89 80~70 ~64, 62ppm
~147 134~120 ~114 ~105 ~89,84 80~70 ~62ppm
~54ppm
Overlap
OO O
OH
OH
HO O
OH
O
OHOHHO
OHHO
OHHO
n
~147 ~130 ~124 ~105 ~89,84 80~70 ~62, 54ppm
cotton
13C CP/MAS NMR of NB & AB cotton
NB-cotton
AB-cotton
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
NO2
123
4 56
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
NH2
~147 134~120 ~114 ~105 ~89,84 80~70 ~62ppm
~148 140~125 ~116 ~105 ~89,84 80~70 ~62ppm
13C CP/MAS NMR of NB & AB cellulose
NB-cellulose
AB-cellulose
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
NO2
123
4 56
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
NH2
~147 ~130 ~124 ~105 ~89,84 80~70 ~62, 54ppm
~147 140 ~124 117 ~105 ~89,84 80~70 ~62ppm
DSC data for AB cotton & cellulose
• Endotherms in first runs: Polymer relaxation and loss of water• NB cotton and cellulose: broad endotherm peak at 30~80C
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
-50 0 50 100 150 200 250
Temperature (deg C)
Hea
t fl
ow
Exo
up
(m
W)
AB cellulose
AB cotton
Heating
Cooling
TGA data for NB & AB cotton
Cotton NB-cotton
AB-cotton
Decomposition
(ºC)
~350 ~260
~445
~170
~340
Char content % at 500ºC
5.0 14.0 45.0
Char content % at 600ºC
2.0 1.0 37.0
cotton NB-cotton
AB-cotton
TGA data for NB &AB cellulose
cellulose NB-cellulose
AB-cellulose
Decomposition
(ºC)
~300 ~250
~290
~190
~330
Char content % at 500ºC
6.0 15.0 60.0
Char content % at 600ºC
2.0 6.0 55.0
cellulose NB-cellulose
AB-cellulose
Thermal Degradation Mechanism
OO
O
O
OH
OHHO
OHHO O O
OO
OH
O
OHHO
OHHO
NH2
H2N
Thermal decomposition and Coupling
OHOOH
HO
O
HN O
HO OHOH
NH
+ other decoposition products
Curing reaction of the NB & AB cotton with Bisphenol-A diglycidyl ether (BADGE)
OO
OO
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
NH2
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
HN
OH
O OO
+
DSC cure
The second NH does not react see: Sachinvala et al. J. Polym. Sci. 1998, 36, 2397-2413
DSC data for NB & AB cotton with BADGE
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
-50 0 50 100 150 200 250 300 350
Temperature (deg C)
He
at
flo
w E
xo
up
(m
W)
AB cotton w/BADGE
NB cotton w/BADGE
• -30 ºC ~ 300 ºC, 20 ºC/min, 3 cycles• Water and/or methanol are known to accelerate decomposition and cure near 280-300 ºC. Hence, the exothermic spike in the first run.• So why no changes in the second and third heating and cooling runs?
DSC data for NB & AB cellulose with BADGE
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350
Temperature (deg C)
Hea
t fl
ow
Exo
up
(m
W)
AB cellulose w/ BADGE
NB cellulose w/ BADGE
• -30 ºC ~ 300 ºC, 20 ºC/min, 3 cycles• Same spike and no changes in the heating and cooling runs in DSC
Proposed Explanation for Curing without Observable Enthalpy Changes
• Aryl Amino groups react with epoxies beyond 280 deg. C;
• Hydroxyl group mediated curing does not show heat changes because the enthalpies of bonds made and bonds broken are about the same. That is, delta-H of bonds broken minus bonds formed ~ zero;
• DSC is not sensitive to show enthalpy changes in ring strain energy as the epoxy ring opens;
• Therefore, changes in enthalpies in DSC heating and cooling runs are not readily seen.
• Mechanism and curing of epoxy groups by aryl double bonds is not known, and is under investigation.
TGA of the AB cotton & cellulose with Bis-phenol-A diglycidyl ether (BADGE)
AB-cotton + BADGE
Char at 500deg.C: AB-cellulose-BADGE > AB-cotton-BADGE because of greater
substitution of AB groups in cellulose
AB-cellulose + BADGE
Plane cellulose
AB-cellulose AB-cotton AB-cellulose w/BADGE
AB-cotton w/BADGE
Decomposition
(ºC)
~300 ~190
~330
~170
~340
~305
~350
~300
~365
Char content % at 500ºC
6.0 60.0 45.0 50.0 28.0
Synthesis of Pentafluoro-benzyl cellulose
• Cellulose was subjected to a solvent exchange• Prepared solution of 3.0g Cellulose, 6.7g LiCl, and ~100ml DMAc• Added 0.23g DMAP and 1.93g of pentafluorobenzyl bromide• Heated to 80ºC for overnight under nitrogen • Work up and obtained a brown gel solution in high yield• Obtained film, fiber and powder
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
OO O
OH
O
HO O
OH
O
OHOHHO
OHHO
OHHO
n
reducing endnon-reducing end
1-step
cellulose
OH
Pentafluoro-benzyl cellulose
FF
F
FF
Conclusions and Future Work
• New nitro benzyl (NB) and amino benzyl (AB) cotton and cellulose derivatives were prepared and characterized by FT-IR, 13C CP/MAS NMR, DSC and TGA
• Benzylation occurred better in cellulose than in cotton because of ease of swelling the lower MW cellulose 100-1000 DP over cotton > 10,000 DP
• Nitro- and amino-benzylated cellulose and cotton cured Bis-phenol A diglycidyl ether (BADGE). No examples of these composites exist in the literature.
• TGA studies show high thermal stability cured AB-cellulose-BADGE composites
• 1H, 13C NMR, swelling studies, contact angle, and mass characterizations in addition to applications development are on going
• Pentafluorobenzyl cellulose will be continue study about physical properties
Acknowledgements
• Funding from USDA-ARS, CRIS:6435-41000-081-00D
• Funding from USDA-ARS, CRIS:6435-41000-094-00D