Advanced polymeric silver nanocomposites

Advanced polymeric silver nanocompositesDr Panagiotis Dallas

Tato prezentace je spolufinancována Evropským sociálním fondem a státním rozpočtem České republiky.

Advanced polymeric silver nanocompositesDr Panagiotis Dallas


Organic and supramolecular chemistry are forms of fine art


Nanoscience and polymer chemistry are direct analogues to civil engineering and architecture


Magn(Fe2O

Car

Nanomaterials (dimensions <50 nm) can possess significantly important MAGNETIC, OPTICAL, CATALYTIC AND MAGNETIC, OPTICAL, CATALYTIC AND BIOLOMEDICALBIOLOMEDICAL properties and by incorporating them in polymers these properties are inherited in the resulting nanocomposite.

The magnetic and optical properties of materials in the nanoscale are size and shape dependent.

Nanoparticles can be surface functionalized with different organic molecules, e.g. iron oxides with carboxylate anions, noble metals with Car

gra(ne

carboxylate anions, noble metals with amines or thiols and even self assemble in perfectly arranged structures which is crucial in the manipulation of the nanoparticles’ properties and in various applications, e.g. development of high density recording media.


netic Fluorescent MetallicO3, FePt, EuS) (CdSe, CdS) (Ag, Au, Pt, Pd)

rbon nanotubes (1 D) and fullerenes (0 D)rbon nanotubes (1-D) and fullerenes (0-D)-aphene (2-D) now joins the familyetwork of carbon double bonds)


ll Common plastics (Common plastics (nylon, pmma, polystyrene)

ll DendrimersDendrimers

ll Conductive polymersConductive polymers

ll Conjugated polymersConjugated polymers

Aque

ous s

olution

C

COO

n

CH3

Methyl m

ll Biopolymers: Biopolymers: Carboxymethylcellulose,

polysaccharides.[5]

[1] © Travan A. et al. Biomacromolecules 2009, 10, 1429

Interfacial polymerization

OMe

CH2 + xAIBN

TolueneC COOMe

O-O

COOMe

C

C

CH2

O O-

CH3

methacrylate

Methacrylic acid absorbed on the surface of iron oxide nanoparticle Poly(methyl methacrylate)

Principle requirements:Ø Homogenous dispersion of

nanoparticles inside the matrixØ Fine size distributionØ Controlled morphology- going

beyond polymer filled nanocomposites

Advantages:

1429

Advantages:ü Plastics are transparent (>90% for pmma) and have high tensile strength.ü Dendrimers are completely symmetrical and functional macromolecules.ü Biopolymers are biocompatible and low cost materials.ü Block copolymers tend to self assemble to perfectly organized nanostructures

l A prescribed morphology is required for the optimum accomplishment of the properties of both components.

l Liquid like behavior: Functionalization of the surface with silanes or organic molecules that exhibit a low temperature melting point can lead to meltable or liquid nanoparticles (Nanoscale Ionic Materials-NIMS). [2]

l Solubility in various solvents: Nanoparticles lack solubility so appropriate coating makes them either organophilic or hydrophilic.

l Polymers, ligands and surfactants control the size and shape growth of the nanoparticles and the surface functionalization of the nanoparticles and polymer chains can manipulate the interparticle distance and interactions. [2]

Utilization of the polymer’s functionality: The l Utilization of the polymer’s functionality: The polymers functional groups makes them versatile tools for building networks or attaching them on surfaces following a layer by layer approach.

l Self assembly of nanoparticles: According to the polymers tendency to form ordered and symmetric patterns. [3]

[2] a) A.B.Bourlinos. Adv.Mater. 2005, 17(2), 234-237 b) R.Rodriguez. Adv.Mater. 2008, 20(22), 4353-4358

[3] S.I.Lim, C.J.Zhong. Acc.Chem.Res. 2009, 42(6), 798


A prescribed morphology is required for the optimum accomplishment of the properties of both components.

Functionalization of the surface

temperature melting point can lead to meltable or liquid

Nanoparticles lack solubility so appropriate coating makes them either

Polymers, ligands and surfactants control the size and

functionalization of the nanoparticles and polymer chains C C

OO

CC

O O

COOC O

OCOOMe

MeOOC

COOMe

COOMe

COOMeMeOOC

MeOOC

COOMe

MeOOC

COOH

COOMeMeOOC

COOMeMeOOC

-

Meltable carbon nanotubes can be also soluble in toluene. [4] © Carbon 2007, 45, 1583-1585, Bourlinos, A.B. et.al

polymers functional groups makes them versatile tools for building networks or attaching them on surfaces

According to the

MeOOC

CH2

CH

H2C

HC

MeOOC

COOMe

COOMe

COOMe

MeOOC

COOMeMeOOC

MeOOC COOMe

COOMe

COOMe

MeOOC

COOMe

COOMe

COOMe

COOMe

Chemical bonding of iron oxide nanoparticles with pmma after surface functionalization with methacrylic acid. [5] © Nanotechnology 2006, 17, 2046-2053, Dallas, P. et.al


l Even if the electrochemical polymerization of pyrrole and anilinewas firstly performed in 1915, the interest expanded after the discovery of conductivity in polyacetylene by Prof.H.Shirakawa (1977)

ll 2000: 2000: Nobel prize in Chemistryawarded to Prof.H.Shirakawa, Prof.A.MacDiarmid and Prof.A.Heeger for their discovery and development of conductive polymers.

l Electronic conductivity. Usually it follows a semiconducting behavior,

Properties of conjugated and conductive polymers

follows a semiconducting behavior, however there are many reports demonstrating a metallic conductivity.

l Low band gap absorptions

[6] K. Lee., et al Nature 2006, 41, 65. [7] © P. Dallas.,et al. Polymer 2007, 48, 3162

Properties of conjugated and conductive polymers

50 100 150 200 250 300 350

0,01

0,1

1

10

100

Con

duct

ivity

(Ω

-1cm

-1)

Temperature (oC)

Semico

nduc

tor-in

sulat

or

Metal

Metal-insulator transiotion in polyaniline nanoneedles due to Peierls instability (1-D conductors are intrinsically unstable) [7]

Cu, Au, Ag ~ 105

Polyacetylene~ 102

Polyaniline~1-10

Polystyrene~ 10-10

conductors are intrinsically unstable) [7]

Con

duct

ivity

val

ues

l Sensor applications: The bridging amine units enable them to serve as excellent redox sensors for various organic and inorganic molecules (e.g. NH3, N2O4, glycose) [8]

l Specifically: polyaniline exhibits different oxidation states, each one with different colour and accordingly UV-Visible absorptions. Only the emeraldine salt form is conductive and the presence of the above mentioned species induced immediate changes in the conductivity of the polymer thus serving as excellent sensor.

l Even if they have lower conductivity than conventional metals they have major advantages like low weight, easy preparation and processability, dispersion in various solvents and low cost.

Applications of conjugated and conductive polymers

and processability, dispersion in various solvents and low cost.

[8] (a) X. Li., et al J.Phys.Chem.C. 2009, 113, 69-73. (b) M. Zhao.,et al. J.Phys.Chem.C 2009, 113, 4987-4996.

[9] A.P.Zoombelt. Org.Lett. 2009, 11(4), 903-906

Photovoltaics and solar cells due to low band gap and strong absorptions in the visible light region. [9]

Applications of conjugated and conductive polymers

4996.

The pioneering work of Prof.Sir Richard Friend (Cavedish Laboratory, University of Cambridge, England) paved the way for Light Emitting Diodes and flat panel screens based on polymers.

Interesting aspects of silver nanoparticles

l Catalytic activity: Reduced size increases the fraction of surface atoms which are crucial in catalysis. Ligand-or polymer stabilized colloidal noble metals have been used for many years as catalysts for the hydrogenation of unsaturated organic molecules. Additionally, there is a special interest in developing “green” methodologies for catalyzing organic reactions in aqueous solutions.

l Antibacterial activity

Left: Au nanospheres and nanorods (a,b) and Ag nanoprisms (c

Right: AuAg alloy nanoparticles with increasing Au concentration (d), Au nanorods of increasing aspect ratiandlateral size (f).

l Surface plasmon resonance

[10] © Luis M.Liz-Marzan. Mater.Today. 2004, 26.


Interesting aspects of silver nanoparticles

4th Century AD: Lycurgus cup1857: Michael Faradayreported the color of colloidal gold

The free electron of the noble metal nanoparticles surface interact with UV and Visible light and the excitations result in different absorptions easily observed in the corresponding spectrum.All these absorptions are size and shape dependent.

Left: Au nanospheres and nanorods (a,b) and Ag nanoprisms (c)

Right: AuAg alloy nanoparticles with increasing Au concentration (d), Au nanorods of increasing aspect ratio (e), and Ag nanoprisms with increasing lateral size (f). [10]

size and shape dependent.


Organic molecules and natural products as antibacterial agents

l Silver has been known for centuries as an effective antibacterial agent.

l 1930: Sir Alexander Flemingrefines penicillin extracts

l Bacteria have evolved mechanisms against these β-lactam antibiotics by lactam antibiotics by hydrolyzing the lactamic ring. On the other hand they have not yet evolved mechanisms of action against silver.


Organic molecules and natural products as antibacterial agents


Antibacterial activity of silver

Even if the exact mechanism is not clearly resolved numerous studies indicate the following interactions between silver and bacteria [11]:

Ø Silver cations bind to negatively charged components of proteins and nucleic acids, thereby causing structural changes and deformations. In general, they are well known to interact with electron donor functional groups like thiols, phosphates, hydroxyls, imidazoles, amines.

Ø It is considered that silver cations inhibit ATP synthesis via binding to the ATP synthesis enzyme molecules in the cell wall and are even entering the cell and binding with DNA.

Ø It has been confirmed the incorporation of silver into the cell membrane structure

Ø The outer membrane of e-coli cells: it is predominantly Ø The outer membrane of e-coli cells: it is predominantly constructed from tightly packed lipopolysaccharide (LPS) molecules, which provide an effective permeability barrier. Metal depletion may cause the formation of irregular-shaped pits in the outer membrane.

Ø Already has been reported the interaction of silver with viruses like HIV-1. [12]

[11] a) I.Sondi et al.J.Colloid Interf.Sci. 2004, 275, 177-182 b) J.Jain et al. Mol.Pharmaceutics. 2009 (in press) 10.1021/mp900056g[12] J.L.Elechiguerra. et al. Journal of Nanobiotechnology 2005, 3, 6


WARNINGWARNING!!Dangers from overover--useuse of antibacterial agents:- Allergies- Asthma- Weak immune system especially for kids

[13] a) P.Gibson et al. Pediatric Pulmonology 2003, 36, 209–215 b)

Silver cations bind to negatively charged components of

known to interact with electron donor functional groups like thiols, phosphates, hydroxyls, imidazoles, amines. It is considered that silver cations inhibit ATP synthesis

the cell wall and are even entering the cell and binding

It has been confirmed the incorporation of silver into the

cells: it is predominantly Pulmonology 2003, 36, 209–215 b) F.Marra. et al. Chest 2009 (in press) c) J.P.Zock. et al. American Journal of Respiratory and Critical Care Medicine2007, 176. 735-741

cells: it is predominantly

Already has been reported the interaction of silver with

182 b) J.Jain et al. Mol.Pharmaceutics.


One-step reduction of silver cations

l The oxidation potential of silver makes it ideal candidate for the initiation of oxidation polymerization of various monomers, for example pyrrole or pyrrole or rhodanine.rhodanine.

ll DendrimersDendrimers can also immediately reduce silver cations towards metal nanocomposites. 14©

[14] © H.Kong., et al. Biomacromolecules 2008, 9, 2766


step reduction of silver cations

can also immediately reduce

NH

-e-

NH

+.

py

NH

NH++

-2H+

NHN

H

-e-

NHN

H

+.

, 9, 2766-2681.


Silver polypyrrole composites: thin films through interfacial polymerization

Pyrrole/CHCl3

AgNO3/H2O

111

200

220 311

Left: X-ray diffraction pattern indicating

30 40 50 60 70 80

inte

nsity

(a.

u)

2θ degrees

220 311

222

[15] © P.Dallas., et al. Polymer 2007, 48, 2007-2013.


pattern indicating the crystal plains of metallic silverRight: The % wt percentage of silverin the nanocomposite can be estimatedthrough thermal analysis

Silver polypyrrole composites: thin films through interfacial polymerization

95

100

ray diffraction pattern indicating

100 200 300 400 500 600

65

70

75

80

85

90

95

Wei

ght l

oss

(%)

Temperature (oC)

Polypyrrole/Ag

2013.


pattern indicating the crystal plains of

Right: The % wt percentage of silverin the nanocomposite can be estimatedthrough thermal

Newly developed triazine based polymers

P

N

N

P

P

N

+H 2N

NH 2+

+H 2N

NH 2+

+H 2N

+H 2N

+H 2N

+H 2N

NH 2+

+H 2N

+H 2NCl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -Cl -

1 0 2 0 3 0 4 0

Inte

nsity

(a.u

.)

0 .4 5 n m

(b )

(a )

3 n m

0 .3 2 n m

2 θ (o )

H 2N

+H 2N

NH 2

Cl -

[16] © P.Dallas., et al. Polymer 2008, 49, 1137-1144.[17] © A.B.Bourlinos., et al. Eur.Pol.J. 2006, 42, 2940

Cyanuric chloride:Monosubstituted and planarPhosphonitrilic chloride:Disubstituted and the sites have an in and out of plane orientation.

Newly developed triazine based polymers

Ø These polymeric networks are synthesized through nucleophilic attach of aromatic diamines like 4,4’ bipyridine, 1,4 phenylenediamine or benzidin in the reactive chlorine anions of either cyanuric or phosphonitrilic chloride.Ø Chlorines are acting as counterbalancing anions and can be exchanged with other or inorganic anions thus expanding the d-spacing of the network (see XRD patterns below).Ø They can be considered as organic-inorganic hybrid analoques of zeolites and layered double hydroxides.

1144.42, 2940-2948

5 10 15 20 25 30 35 40 45

inte

nsity

(a.u

)

2θ degrees

a) benzidin/cyanurin polymer b) benz/cyan after exchange with SO

4

2-

a)

b)

Cyanuric chloride:Monosubstituted and planarPhosphonitrilic

Disubstituted and the sites have an in and out of plane orientation.

Electrochemical and redox activity

N

NH2N N

N

N

N

N

NHN NH

N

N

N

Cl-

N

N

NN N

N

N

N

.+

-2e-

-2e-

-2H+

+ Cl-+Cl-

-2H+

.+

Cl-

Dark green

Blue

Light N

NH2N NH2

N

N Light purple

Due to the bridging protonated amine untits the polymer are chemically and electrochamicelly active. Cyclic voltammetry steps induce significant changes in the color and the oxidation state with an impact in the absorptions of the UV-Visible region

Electrochemical and redox activity

-2

-1

0

1

2

3

4

I/m

A

benz/cyan0.79 V 1.22 V

0.45 V-0.73 V

-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0 2,5-3

-2

E/ V vs SCE

-0.73 V

Due to the bridging protonated amine untits the polymer are chemically and electrochamicelly active. Cyclic voltammetry steps induce significant changes in the color and the oxidation state with an impact in the

Optical properties

Polyaniline exhibits a well established formation of a

300 400 500 600 700 800 9000,0

0,1

0,2

0,3

0,4

0,5

Abs

orpt

ion

(a.u

)

Wavelength (nm)

benz/cyan

833 nm607 nm

423 nm

361 nm

established formation of a polaron band which results in three distinct absorptions in the UV-Visible spectra. Similar was the spectrum of benzidin/cyanuric polymer (up). It can be assigned to a partial formation of radical cations in the bridging amine units. EPR studies have been very powerful tools for the study of such materials.

Conduction bandConduction band

Valence bandValence band

Polaron bandPolaron band

Optical properties

400 500 600 700 800 900

Abs

orpt

ion

(a.u

)

Wavelength (nm)

575 nm

500 nm470 nm

Abs

oprtio

n (a

.u)

330 nm

400 500 600 700 800 900

700 nm

Abs

oprtio

n (a

.u)

Wavelength (nm)

UV-Visible spectrum of 3-D phosphotriazine based polymers before and after oxidations with S2O8

2-.

Morphology of the polymers


Morphology of the polymers

The macroscopic morphology of the polymers is following the microstructure and themacromolecular chains orientation.

(I) An Electron Microscopy study of the 2-dimensional cyanuric derivative reveals the presence of individual or fused submicrometer grains with a striated surface grains with a striated surface texture, platy morphology and multi-layered structure at the edges. These features combined are suggestive of a lamella phase.(II) The 3-dimensional growth of the phosphonitrilic derivatives results in elongated, hollow morphologies.


Ø Redox reaction with silver cations results in silver

Synthesis of silver nanocomposites on the surface of triazine based polymers

cations results in silver nanoparticles that inherit the composites with high antimicrobial activity.Ø Amines, amides, imines and thiols are excellent capping agents for noble metals as such the nanoparticles are well attached on the surface of the polymer


Synthesis of silver nanocomposites on the surface of triazine based polymers

300 400 500 600 700 800 900

Abs

orba

nce

Wavelength (cm)

PolymerSilver nanoparticles


Future prospects for polymer chemistry

Porous polymeric networks with palladium nanoparticles are promising candidates for hydrogen storage materials and fuel cell technology. [19]

Palladium nanoparticles are excellent absorbents of hydrogen

The porous network of the support will enable the penetration and encapsulation of gas molecules, e.g. hydrogen. Its functional sites can selectively arrange the palladium nanoparticles.nanoparticles.

[18] a) A.Thomas et al. Macromol.Rapid. Commun. 2009, 30, 221b) F.Cacialli Mater.Today 2004, 24

[19] Y.E.Cheon. et al. Angew.Chem.Int.Ed. 2009, 48, 2899-2903

Future prospects for polymer chemistry

Supramolecular chemistry (Nobel prize in 1987: J.M.Lehn, D.J.Cram, C.J.Pedersen) is a form of (chemical) art that enables the control of non-covalent interactions like hydrogen bonding for the construction of hyper-molecules with advanced functionalities and symmetry. This can light the way for new and advanced polymers that will enable the perfect formation and control of nanomaterials according to their structure.

Crown ether phthalocyanine

30, 221

2903

phthalocyanine self assemble to nematic Nano-structures: potential applications in non-linear optics, chemical sensors, nanodevices.

l The use of nanocomposites will reach 45 million kg by 2011. As such the challenges are in the hands of polymer chemists to optimize the performance and the synthesis of new composite materials.

l Further reading:

Nanocomposites and interparticle distance control:

I. Vaia, R.A., Maguire, J.F. Chem. Mater. 2007, 19, 2736

II. Crooks, R.M., et al. Acc.Chem.Res. 2001, 24(3), 181.

III. Lim, S.I., Zhong, C.J. Acc.Chem.Res. 2009, 42(6), 798.

IV. M.Zorn., ACS Nano. 2009, 3(5), 1063-1068

Silver/polymer nanocomposites:

V. Gladitz, M., Reinemann, S., Radusch, H.J. Macromol. Mater. Eng. 2009, 294,V. Gladitz, M., Reinemann, S., Radusch, H.J. Macromol. Mater. Eng. 2009, 294,

VI. Rhim, J.W. et al. J. Agric. Food Chem. 2006, 54, 5814

VII. C.N.Lok et al J.Proteome Res. 2006, 5, 916-924.

Recent advances in polymer science:

VIII. A.Thomas et al. Macromol. Rapid Commun. 2009, 30,


The use of nanocomposites will reach 45 million kg by 2011. As such the challenges are in the hands of polymer chemists to optimize the performance and the synthesis of new

2736-2751.

181.

42(6), 798.

Macromol. Mater. Eng. 2009, 294, 178–189.Macromol. Mater. Eng. 2009, 294, 178–189.

, 54, 5814-5822.

Macromol. Rapid Commun. 2009, 30, 221-236.


Acknowledgements

l Dr.A.B.Bourlinos

l Prof.R.Zboril

l Dr.D.Jancik

l Dr.D.Niarchos

l Dr.D.Petridis

Dr.V.Georgakilasl Dr.V.Georgakilas

Contact information: Dr Panagiotis Dallas, Centre of Nanomaterial Research & Department of Physical Chemistry, Palacky University, Olomouc, Czech Republic.


*The original research work presented here, was conducted in both the Centre of Nanomaterial Research of Palacky University and the Institute of Materials Science, NCSR “Demokritos”, Athens, Greece.

Acknowledgements

Dr Panagiotis Dallas, Centre of Nanomaterial Research & Department of Physical Chemistry, Palacky University, Olomouc, Czech Republic. E-mail: [email protected]


*The original research work presented here, was conducted in both the Centre of Nanomaterial Research of Palacky University and the Institute of Materials Science, NCSR “Demokritos”, Athens, Greece.

Documents

Advanced polymeric silver nanocomposites