THE EFFECT OF POLYMER IN COLLOIDAL SUSPENSIONS

The Effect Of Polymer In Colloidal Suspensions

Table of Content

DATA ANALYSIS1

Experimental8

Materials8

Preparation of polymer -clay nanocomposite aqueous colloidal suspension9

Measurements10

RESULTS ANALYSIS11

DISCUSSION22

Dielectric dispersion spectra and electrode polarization relaxation behaviour22

Ac Conductivity Spectra29

Electric modulus spectra33

Complex impedance spectra34

CONCLUSION36

REFERENCES40

DATA ANALYSIS

Organic polymers, loaded with small amount of montmorillonite (MMT) clay result in polymer -clay nanocomposites (PCNs). In last two decades, PCNs have evoked an intense industrial and academic research, due to their outstanding mechanical, thermal, chemical and electrical properties over pure polymers and . The MMT clay which is also called inorganic polymer has a laminar structure and excellent hydrophilic and cation exchange properties . Its sheet dimensions in the length and width can be in hundreds of nanometers but thickness is only one nanometer. The MMT clay is composed of units made of two silica tetrahedral sheets centered with an alumina octahedral sheet, which is called 2:1 phyllosilicate and chemically it is a metal silicate. Its layers are stacked by weak dipolar or van der Waals forces, and it has both surface and edge charges. The charges on edges are easily accessible to modification, but they do not accomplish much improvement in interlaminar separation. These sites represent an opportunity for attachment of functional group of polymers during the synthesis of PCN materials and . In water or polar organic solvents, the MMT clay has excellent swelling properties owing to the intercalation (absorption) of solvent molecules in the clay galleries and also the adsorption of solvent molecules on its external surfaces of the sheets. (See Fig 1)

FIG 1

Three methods commonly used for the synthesis of PCNs are in situ polymerization , solvent intercalation and polymer melt intercalation . In case of hydrophilic polymers and clay, the PCNs films are frequently prepared by casting solution intercalated nanocomposite material directly onto a glass plate. In PCNs aqueous solutions, intercalation and exfoliation are two extremes for the clay structures. In intercalated, polymer is located in the clay galleries, expanding the clay structures but retaining some long distance register between the platelets or sheets. Whereas, in case of exfoliated, the original face-to-face structure of the clay platelets is destroyed and single clay sheets are randomly dispersed in the polymeric solution. Complete exfoliation of all the individual platelets is very difficult to achieve and most PCNs solutions contain region of both intercalated and exfoliated structures and their ratio depends on the polymer and clay interaction in the solutions. The structural morphology and polymer intercalation properties of the PCNs films are widely characterized by SEM and TEM micrographs, and XRD and FTIR spectroscopy. The characterization of dielectric properties of PCNs films have their significant applications in integrated circuits, microelectronics and insulating devices, and membrane technology , and . The PCNs aqueous colloidal suspension and gels are widely used as electrolyte and for improving barrier coating efficiency due to colloidally stable of clay sheets in suspension and , and effective wound dressing . In order to realize the macroscopic properties of nanocomposites from molecular concepts, one must understand the molecular ...