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SYNTHESIS AND APPLICATION OF
SOME POLYSILOXANE
IMMOBILIZED LIGAND SYSTEM
SYNTHESIS AND APPLICATION OF
SOME POLYSILOXANE
IMMOBILIZED LIGAND SYSTEM
Prepared by :Mysaa’a. S. Al-Batnegy
Suhad. S. El-TanaNoha M. Motawe’a
Chemistry DepartmentChemistry DepartmentIslamic University of GazaIslamic University of Gaza
Supervised bySupervised by : : Dr. Nizam M. El-Dr. Nizam M. El-
AshgarAshgarMay /2007May /2007
Synthesis Of Synthesis Of Immobilized Ligand Immobilized Ligand
SystemsSystemsThese immobilized ligand systems have been made
by two different routes:
1. silica gel route: Silica is the most common substance on earth. It occurs in
nature as:• Crystalline phase (quartz, rice and barely).• Amorphous forms (silica glass).
Synthesis of silica gelSynthesis of silica gel• Formation of a wet gel.
• Drying of the wet gel.
Ex:
nCl Si
Cl
Cl
Cl + 4nH2OSiHO
OH
OH
OH
n
Silicon tetrachloride Silicic acid
SiHO
OH
OH
OH
n
Silicic acid
O Si O
n
OH
OH
Polysilicic acid
Modification method of Modification method of surface silicasurface silica
By chemical reaction of silica as shown:
OH
O35% HCl
reflux
OHOHOH
Where L is an organofunctional group.
OH
OHOH + (RO)3Si-L
acetic acidOH2
OOO
Si L
2. The sol gel route:It is a one spot reaction in which the
tetraalkoxy silane Si(OR)4 and the silane coupling agent (RO)3Si(CH2)3X mix together in an alcoholic solution in the presence of an acid or base catalysis, where hydrolysis and condensation occurred simultaneously.
The two strategies of The two strategies of preparation of the preparation of the
immobilized polysiloxane immobilized polysiloxane
ligand systemligand system • To prepare the silane with complexing group and then to immobilized
the complexing ligand by hydrolytic condensation reaction with tetra ethoxy silane.
Ex:
R = Me or Et R’ = Organofunctionalized ligand
• The post treatment of the polysiloxane with the complexing ligand.
Ex:
Si(OR)4 (RO)3SiR'ROH
O
O
Si
O
R'+ H2O/Cat.
O
O
O
Si(CH2)3Cl
O
O
O
Si(CH2)3IAcetone
+ NaI 48 hr, 70 C
o
Features of Features of polysiloxanepolysiloxane
• Insoluble cross-linked organosilicon polymers with a controllable porous structure.
• They are intermediates in composition between the pure inorganic silica and organic polymers such as polystyrene.
• Although the chain is entirely inorganic, with alternating Si and O
atoms, organic side groups are attached to the silicon atoms.
• Has an extraordinary flexibility of the siloxane backbone.• • Si-O bond is significantly longer than the C-C bond.
• Si-O-Si bond angle of 143 > tetrahedral angle.
Important applicationImportant application
It is includes high performance elastomers, membranes, electrical insulators, water repellent sealants, adhesives, protective coatings, hydraulic, heat transfer, dielectric fluids, biomaterials, catalyst supports, chromatography, extraction and uptake of metal ions from aqueous solutions and encapsulation
of organic compounds.
The first strategy (sol The first strategy (sol gel process)gel process)
Hydrolytic polycondensation of a mixture of tetraethyl orthosilicate (TEOS) and the appropriate silane coupling agent in a definite mole ratio using acid or base catalysts.
The process steps:1- HydrolysisBy mixing low molecular weight tri or/and tetra alkoxysilanes with water
in present of a homogenization agent. The hydrolysis catalyzed by acid or base.
SiOR + H2O SiOH + ROH
2- Polycondensation Through silanol-silanol condensation SiOH + SiOH Si-O-Si + H2O Silanol-ester condensation. SiOR + SiOH Si-O-Si + ROH Where: R = CH3 or C2H5.
Further polycondensation Further polycondensation to form SiOto form SiO22 net work net work
OH
OH
OH
LOH
OH
O O OO
O O
O O
O
O
O
O
L
L
L
O
O
OOO
O
O
O O O
Si Si Si Si Si
S Si
S S
Si
Si
n
Gelation, Drying and Gelation, Drying and AgingAging
• GelationInterconnection between particles of the sol increases forcing
the sol to become more viscous (gel-point) so lose its fluidity.
• DryingEvaporation of water and organic solvent from the pores of the glassy
material.Shrinking of solid gradually (In some cases, the final volume of the
xerogel is 10% of the initial volume of the gel).Large internal pressure gradients in the wet pores. This process causes
cracking and fracture in large monoliths. Addition of surfactants, such as Triton-X, were suggested to prevent these fractures
Drying the wet gel under monitored conditions also, give free cracks monolith.
• AgingThe polycondensation reaction, formation of new bonds, water and alcohol still occur as a function of time.Additional cross-linking and spontaneous shrinking occur.So structure and properties of the gel continue changing with time.The gel is aged to complete reaction.The strength of the gel increase with aging.
SiOR + H2O SiOH + ROHSiOH + SiOH SiOSi + H2
What do you know What do you know about coupling agentabout coupling agent? ?
• It have the general formula X3SiR.(Where X is a hydrolyzable group and R represents an organofunctional group).
• It combine the organic chemistry of organofunctional groups with inorganic chemistry of silicates.
• It have been used widely to modify surfaces for chemical applications, to immobilize chelating functional groups on silica gel and to prepare organofunctionalized polysiloxanes.
Advantages of Polysiloxane Advantages of Polysiloxane Immobilized Ligand SystemsImmobilized Ligand Systems
• The physical rigidity of their structures.• High abrasion resistively.• Negligible swelling in both aqueous and organic solutions.• Chemical inertness (low interaction with analytes).• Slower poisoning by irreversible side reactions.• High biodegradation, photochemical and thermal
stability.• High capacity of functionalized groups.• Uniform distributions of ligand sites within the polymer
particles.• Readily modified by a variety of functional groups to be
immobilized either before or after polymerization.
Drawbacks of Drawbacks of PolysiloxanesPolysiloxanes
• Hydrolysis at high pH ( 12).
• Leaching of the functional groups from the support surface into the solution.
Application of Polysiloxane Application of Polysiloxane Immobilized Ligand SystemsImmobilized Ligand Systems
• The extraction and isolation of metal ions.• Metal ion separation in columns chromatography.• As catalysts in a variety of reactions. • Encapsulation of organic and biochemical compounds.
Preparation of Preparation of polysiloxane immobilized polysiloxane immobilized
ligand systemligand system1. Preparation of 3-Iodipolysiloxane (P-I) .• Preparation of the silane agent by the reaction of
3-chlorotrimethoxysilane with an excess amount of sodium iodide using dry acetone as a solvent .
• Hydrolytic polycondensation of the 3-iodotrimethoxysilane agent with tetraethylorthosilicate (TEOS), in the ratio 1:2 respectively .
(CH3O)3Si(CH2)3Cl + NaI (CH3O)3Si(CH2)3I + NaClAcetone
48hr, 70 C
(CH3O)3Si(CH2)3I + 2 Si(OC2H5)4H2O/MeOH
HCL
OOO
Si(CH2)3In
2. Preparation of polysiloxane-immobilized Triamine ligand system (P-TA).
By the reaction of 3-iodopropylpolysiloxane with an excess of
diethylenertiamine in the presence of triethylamine.
(CH3O)3Si(CH2)3NH(CH2)2NH(CH2)2NH2
OOO
Si NH
NH
NH2
+ TEOS
3. Preparation of polysiloxane Iminodiacetic Acid ligand system (P-IDA).
• By the reaction of 3-iodopolysiloxane with diethyliminodiacetate (DEIDA) in the presence of triethyl amine .
• The product then hydrolysis using HCl .
OOO
Si(CH2)3I + NH(CH2COOC2H5)2
Et3NOOO
Si(CH2)3NCH2COOC2H5
CH2COOC2H5toluene
O
O
O
SiCH2-CH2-CH2-N
CH2COOC2H5
CH2COOC2H5
O
O
O
SiCH2-CH2-CH2-N
CH2COOH
CH2COOOH
HCl
P-IDA
4. Preparation of polysiloxane 2-Aminothiophenol ligand system (P-ATP).
By the reaction of 3-iodopolysiloxane with 2-aminothiophenol in ethanol at 60 C for 48 hours .
OOO
Si
OOO
Si(CH2)3N
(CH2)3I +
SH
NH2EtOH
48hr, 60 C S
OOO
Si(CH2)3N
SH
H
5. Preparation of polysiloxane phenylene diamine ligand system (P-PDA).
By dissolving phenylenediamine in ethanol and adding it to 3-iodo propyltrimethoxysilane then adding the product dropwise to TEOS.
(CH3O)3Si(CH2)3Cl +
NH2 NH2
H2O/EtOH(CH3O)3Si(CH2)3-NH NH2
(CH3O)3Si(CH2)3-NH NH2 + 2 (C2H5O)4Si
OOO
Si(CH2)3NH NH2n
Characterization of Characterization of Functionalized Functionalized PolysiloxanesPolysiloxanes
1. 3-Iodipolysiloxane (P-I) .
Elemental Analysis :
Element C% H%Cl% I% C/X
Expected10.51.8037.23
Found9.02.2032.33
2. Triamine polysiloxane (P-TA) .
ElementC%H%N%C/Nmmol N/g
Expected22.75.510.72.57.6
found21.3 4.99.89 2.5 7.1
3. Iminodiacetic acid polysiloxane (P-IDA)
Element
C%H%N%C/Nmmol N/g
Expected
29.14.43.111.01.70
found18.84.11.7312.71.24
FTIR :1. For 3-Iodopolysiloxane (P-I) .
4000.0 3000 2000 1500 1000 400.0
46.6
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62.5
cm-1
%T
3447.69
2930.25
1636.01
1123.31
690.17
461.69
2- For triamine polysiloxane (P-TA) .
3. For iminodiacetic acid polysiloxane (P-DIDA) .
4000.0 3000 2000 1500 1000 600 .0
19.5
22
24
26
28
30
32
34
36
38
40
42
44
46
48
49.7
cm-1
%T
3417.091745.51
1645.77
1073.09
947.81
795.66
4. For iminodiacetic acid polysiloxane (P-IDA)
4000.0 3000 2000 1500 1000 600 .0
7 .6
10
15
20
25
30
35
40
45
50
54.4
cm-1
%T
3441.86
1637.18
1405.38
1082.08
957.51
798.26
Metal Uptake Capacity :1. For Triamine polysiloxane (P-TA) .
Maximum Uptake Co2+ Ni2+ Cu2+
mg M2+/g Ligand 27 34.2 49
mmol M2+/g Ligand 0.46 0.57 0.77
ApplicationApplication
Effect of pH
0
10
20
30
40
50
60
3 3.5 4 4.5 5 5.5 6
pH
mg
M(I
I)/g
Lig
an
d
mg Co(II)/g mgl Ni(II)/g mg Cu(II)/g
Uptake of metal ions by P-TA versus pH values, (72 hr shaking time) .
Chromatographic study Effect of pH on metal desorption
Cu(II) desorbed at different pH values
0
0.5
1
1.5
2
2.5
3
0 50 100 150 200 250
Volume of eluent (mL)
mg
Cu
(II)
de
so
rbe
d
pH 3.6 pH 4 pH 4.4 pH 4.8 pH 5.2
Amount of Cu(II) desorbed as a function of eluent volume at different pH values (flow rate 1.5 mL/min
Relation between total amount of Cu(II) desorbed & adsorbed as a function of pH
Cu(II) desorbed and adsorbed versus pH values
0
5
10
15
20
25
30
35
3 3.5 4 4.5 5 5.5 6
pH
mg
Cu
(II)
Cu(II) desorbed Cu(II) retained
Amount of Cu(II) desorbed and retained at different pH values (flow rate 1.5 mL/min
Metal Uptake Capacity :2. For Iminodiacetic acid polysiloxane (P-IDA) .
Maximum Uptake Co2+ Ni2+ Cu2+
mg M2+/g Ligand 66.93 72.10 84.85
mmol M2+/g Ligand 1.13 1.21 1.33
Effect of pH
0
10
20
30
40
50
60
70
80
2.5 3 3.5 4 4.5 5 5.5 6pH
mg
M(
)/g
Lig
an
d
mg Co(II)/g mgl Ni(II)/g mg Cu(II)/g
Uptake of metal ions by P-IDA versus pH values, (72 hr shaking time) .
Chromatographic study Effect of pH on metal desorption
Cu(II) desorbed at different pH values
0
0.5
1
1.5
2
2.5
3
0 50 100 150 200 250
Volume of eluent (mL)
mg
Cu
(II)
de
so
rbe
d
pH 3.5 pH 4 pH 4.5 pH 5 pH 5.5
Amount of Cu(II) desorbed as a function of eluent volume at different pH values (flow rate 1.5 mL/min) .
Relation between total amount of Cu(II) desorbed & adsorbed
as a function of pHCu( ) desorbed and adsorbed versus pH values
0
5
10
15
20
25
30
35
40
2.5 3 3.5 4 4.5 5 5.5 6
pH
mg
Cu
( )
Cu(II) desorbed Cu(II) retained
Amount of Cu(II) desorbed and retained at different pH values (flow rate 1.5 mL/min) .
Metal ions Separation
Separation of Cu(II), Ni(II) and Co(II)
0
0.5
1
1.5
2
2.5
3
0 100 200 300 400 500 600 700 800
Volume of Eluent
mg
of
M(I
I) d
eso
rb
ed
mg Ni(II) desorped mg Co(II) desorped mg Cu(II) desorped
pH 3.5pH4.5 4.5
pH 5.5
Separation of Co(II), Ni(II) and Cu(II) at different pH values (flow rate 1.5 mL/min).
Metal Uptake Capacity :2. For 2-Aminothiophenol polysiloxane (P-IDA) .
Maximum Uptake Co2+ Ni2+ Cu2+
mg M2+/g Ligand 58.3 66.8 77.3
mmol M2+/g Ligand 0.98 1.12 1.21
Effect of pH
0
10
20
30
40
50
60
3 3.5 4 4.5 5 5.5 6
pH
mg
M(I
I)/g
Lig
an
d
mg Co(II)/g mgl Ni(II)/g mg Cu(II)/g
Uptake of metal ions by P-TA versus pH values, (72 hr shaking time) .
Chromatographic study Effect of pH on metal desorption
Cu(II) desorbed at different pH values
-0.5
0
0.5
1
1.5
2
2.5
3
0 50 100 150 200 250
Volume of eluent (mL)
mg
Cu
(II)
de
so
rbe
d
pH 3.6 pH 4 pH 4.4 pH 4.8 pH 5.2
Amount of Cu(II) desorbed as a function of eluent volume at different pH values (flow rate 1.5 mL/min) .
Relation between total amount of Cu(II) desorbed & adsorbed as a
function of pH
Cu(II) desorbed and adsorbed versus pH values
0
5
10
15
20
25
30
35
3 3.5 4 4.5 5 5.5 6
pH
mg
Cu
(II)
Cu(II) desorbed Cu(II) retained
Amount of Cu(II) desorbed and retained at different pH values (flow rate 1.5 mL/min).
Metal ions Separation
Separation of Cu(II), Ni(II) and Co(II)
0
0.5
1
1.5
2
2.5
3
3.5
0 100 200 300 400 500 600 700 800
Volume of Eluent
mg
of
M(I
I) d
es
orb
ed
mg Ni(II) desorped mg Co(II) desorped mg Cu(II) desorped
pH 3.5
Separation of Co(II), Ni(II) and Cu(II) at different pH values (flow rate 1.5 mL/min) .
ConclusionConclusion• In this study some insoluble functionalized polysiloxane
immobilized ligand systems, have been prepared include:
1. Polysiloxane immobilized triamine ligand system.2. Polysiloxane immobilized iminodiacetic acid ligand
system3. Polysiloxane immobilized phenylnediamine ligand
system4. Polysiloxane immobilized aminothiophenol ligand system• The preparation methods were mainly based on the sol-
gel process, which summarized in hydrolytic polycondensation of TEOS and an appropriate silane coupling agent.
• These polysiloxane immobilized ligand systems were well characterized by some of physical techniques.
• FTIR provided strong qualitative evidences about the functional groups of the immobilized ligands.
• Elemental analysis provided the exact content of the functionalized ligand groups that attached to the immobilized ligand systems.
• These immobilized ligand systems exhibit high potential for preconcentration of divalent metal ions (Co2+, Ni2+ and Cu2+) from aqueous solutions.
• The optimum experimental conditions that studied showed that maximum uptake could be attained at pH 5.5 for 48 hours.
• These immobilized ligand systems were used as chromatographic stationary phases for separation of metal ions in aqueous solution by pH control.
Thank You
