Dr Naveed Zaidi
Senior Research Officer

I graduated with a PhD in synthetic organic chemistry from Loughborough University. In 1990 I started my first postdoctoral position at Durham with Professor O'Hagan in the chemistry department, working on several projects leading to polymers, in 1997 collaborating with the IRC (Prof. Jim Feast) in polyamide research. After spending
a year on the joint project between
chemistry (Prof. Martin Bryce) and physics (Dr. Graham Cross) on the optoelectronic materials. I joined Andy Monkman's OEM group in 1999, and we are currently leading the way into preparing high molecular weight polyaniline at low temperature and also investigating into a better dopant than the one in use at present.

I am a keen squash & badminton player and often beat Andy at badminton to stay even. In summer I play cricket for the staff at Durham, weather permitting, and we have a lovely ground with a good view of countryside. My wife is an excellent cook and my two daughters Ayman and Zarlush keep me busy at home.

A bit about my research and publications:

Polyaniline is one of the most interesting and well studied conducting polymers, showing many potential applications such as re-chargeable batteries, light-emitting diodes, molecular sensors, gas separation membranes, and nonlinear optical materials. Good air and thermal stability make it relatively easy to handle and process and when doped with protonic acids, metallic conduction can be achieved. What makes PANi so attractive is that specific triads of the sulphonic acid doped polymer in acid solvents give rise to a soluble protonated form of PANi, which can be cast as film or even spun as fibre. However, solubility is still limited when high molecular weight PANi is used.

In order to commercialise polyaniline, processability is a most important requirement. Since most conductive polymers are not process friendly, all efforts have been directed towards circumventing this problem. Various approaches have been tried to overcome poor solubility, the most effective being the attachment of bulky alkyl groups. This approach has been tried with polyaniline. The oxidative polymerisation of aniline hydrochloride derivatives in water at low temperature is studied without lithium chloride. The resulting polymers have high molecular weight but the conductivity of the acid doped films is strongly dependent on the alkyl- substituted chain on the two positions.

Recently we reported on the synthesis and characterisation of a new type of polymer, PANiCNQ produced from polyaniline (PANi) and an acceptor molecule, tetracyanoquinodimethane (TCNQ). PANiCNQ combines a fully conjugated nitrogen containing backbone with molecular charge transfer side groups and this combination gives rise to a stable polymer with a high density of localised spins which are expected to give rise to coupling. Magnetic measurements suggest that the polymer is ferri- or ferro- magnetic with a Curie temperature of over 350 K, and a maximum saturation magnetization of 0.1 JT -1 kg -1 . Magnetic Force Microscopy images support this picture of room temperature magnetic order by providing evidence for domain wall formation and motion. The magnetic measurements reveal that the magnetically ordered state develops with time, taking several months to reach completion, X-ray diffraction data demonstrate that there is a concomitant evolution of the polymer chains from an amorphous state to a partially ordered form. Estimates of spin density from integrated ESR lines are larger than values obtained from the saturation magnetisation by a factor of 7 which leads us to tentatively conclude that PANICNQ exhibits ferrimagnetic order. Pictures and publicity here

Only selected Publications

Room temperature magnetic order in an organic magnet derived from polyaniline
POLYMER, 45 (16): 5683-5689 JUL 22 2004

Alkyl substituent effects on the conductivity of polyaniline
ADVANCED FUNCTIONAL MATERIALS, 14 (5): 479-486 MAY 2004

Applicability of the localization-interaction model to magnetoconductivity studies of polyaniline films at the metal-insulator boundary
PHYSICAL REVIEW B, 68 (24): Art. No. 245106 DEC 2003

Doping dependent optical properties of polyaniline films
SYNTHETIC METALS, 135 (1-3): 369-370 Part 1 Sp. Iss. SI APR 4 2003

Doping-dependent studies of the Anderson-Mott localization in polyaniline at the metal-insulator boundary
PHYSICAL REVIEW B, 66 (8): Art. No. 085202 AUG 15 2002

Emeraldine base polyaniline as an alternative to poly (3,4-ethylenedioxythiophene) as a hole-transporting layer
ADVANCED FUNCTIONAL MATERIALS, 11 (6): 407-412 DEC 2001

Infrared optical properties of polyaniline doped with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA)
JOURNAL OF PHYSICS-CONDENSED MATTER, 13 (29): 6297-6306 JUL 23 2001

Electrically conductive PANi multifilaments spun by a wet-spinning process
JOURNAL OF MATERIALS SCIENCE, 36 (13): 3089-3095 JUL 2001

Effect of thermal aging on electrical conductivity of the 2-acrylamido-2-methyl-1-propanesulfonic acid-doped polyaniline fiber
JOURNAL OF APPLIED POLYMER SCIENCE, 79 (13): 2503-2508 MAR 28 2001 .