Chemical syntheses of biodegradable polymers phần 1 ppt

Chemistry of Carbon Nanotubes

Dimitrios Tasis,*,† Nikos Tagmatarchis,‡ Alberto Bianco,§ and Maurizio Prato*,|

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute,

National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Mole´culaire et Cellulaire,

UPR9021 CNRS, Immunologie et Chimie The´rapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche,

Universita` di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Received July 12, 2005

Contents

1. Introduction 1105

2. Covalent Approaches 1105

2.1. Sidewall Halogenation of CNT 1105

2.2. Hydrogenation 1107

2.3. Cycloadditions 1107

2.4. Radical Additions 1109

2.5. Electrophilic Additions 1111

2.6. Addition of Inorganic Compounds 1111

2.7. Ozonolysis 1111

2.8. Mechanochemical Functionalizations 1111

2.9. Plasma Activation 1112

2.10. Nucleophilic Additions 1112

2.11. Grafting of Polymers 1112

2.11.1. “Grafting to” Method 1112

2.11.2. “Grafting from” Method 1112

3. Defect Site Chemistry 1113

3.1. Amidation/Esterification Reactions 1113

3.2. Attachment of Biomolecules 1115

3.3. Grafting of Polymers to Oxidized Nanotubes 1116

4. Noncovalent Interactions 1117

4.1. Polymer Composites 1117

4.1.1. Epoxy Composites 1117

4.1.2. Acrylates 1118

4.1.3. Hydrocarbon Polymers 1119

4.1.4. Conjugated Polymers 1119

4.1.5. Other Nanotube−Polymer Composites 1120

4.2. Interactions with Biomolecules and Cells 1122

5. Endohedral Filling 1125

5.1. Encapsulation of Fullerene Derivatives and

Inorganic Species

1125

5.2. Encapsulation of Biomolecules 1126

5.3. Encapsulation of Liquids 1127

6. Concluding Remarks 1127

7. Acknowledgments 1127

8. References 1127

1. Introduction

The unidirectional growth of materials to form nanowires

or nanotubes has attracted enormous interest in recent years.

Within the different classes of tubes made of organic or

inorganic materials and exhibiting interesting electronic,

mechanical, and structural properties, carbon nanotubes

(CNT) are extremely promising for applications in materials

science and medicinal chemistry. The discovery of CNT has

immediately followed the synthesis of fullerenes in macro￾scopic quantities,1 and since then the research in this exciting

field has been in continuous evolution.2 CNT consist of

graphitic sheets, which have been rolled up into a cylindrical

shape. The length of CNT is in the size of micrometers with

diameters up to 100 nm. CNT form bundles, which are

entangled together in the solid state giving rise to a highly

complex network. Depending on the arrangement of the

hexagon rings along the tubular surface, CNT can be metallic

or semiconducting. Because of their extraordinary properties,

CNT can be considered as attractive candidates in diverse

nanotechnological applications, such as fillers in polymer

matrixes, molecular tanks, (bio)sensors, and many others.3

However, the lack of solubility and the difficult manipula￾tion in any solvents have imposed great limitations to the

use of CNT. Indeed, as-produced CNT are insoluble in all

organic solvents and aqueous solutions. They can be

dispersed in some solvents by sonication, but precipitation

immediately occurs when this process is interrupted. On the

other hand, it has been demonstrated that CNT can interact

with different classes of compounds.4-20 The formation of

supramolecular complexes allows a better processing of CNT

toward the fabrication of innovative nanodevices. In addition,

CNT can undergo chemical reactions that make them more

soluble for their integration into inorganic, organic, and

biological systems.

The main approaches for the modification of these quasi

one-dimensional structures can be grouped into three cat￾egories: (a) the covalent attachment of chemical groups

through reactions onto the π-conjugated skeleton of CNT;

(b) the noncovalent adsorption or wrapping of various

functional molecules; and (c) the endohedral filling of their

inner empty cavity.

As clearly visible from the high number of citations, this

field is rapidly expanding. The information reported in this

review on each literature citation will necessarily be limited

in space. It is the aim of this review to consider the three

approaches to chemical functionalization of CNT and to

account for the advances that have been produced so far.

2. Covalent Approaches

2.1. Sidewall Halogenation of CNT

CNT grown by the arc-discharge or laser ablation methods

have been fluorinated by elemental fluorine in the range

† Department of Materials Science, 26504 Rio Patras, Greece. Telephone:

+30 2610 969929. Fax: +30 2610 969368. E-mail: [email protected]. ‡ Theoretical and Physical Chemistry Institute.

§ Institut de Biologie Mole´culaire et Cellulaire. | Universita` di Trieste. Fax: +39 040 558 7883. E-mail: [email protected].

Chem. Rev. 2006, 106, 1105−1136 1105

10.1021/cr050569o CCC: $59.00 © 2006 American Chemical Society

Published on Web 02/23/2006