Plasma Polymerization:Theory and Practice

INTRODUCTION

Plasma polymerization is gaining importance for last several

years as a tool to modify material surfaces. Organic vapors can

be polymerized at low temperatures using plasma enhancement.

Plasma polymerization can also be used to produce

polymer films of organic compounds that do not polymerize

under normal chemical polymerization conditions because

such processes involve electron impact dissociation and ionization

for chemical reactions.

Organosilicone films prepared by plasma polymerization

provide good optical and mechanical properties. Most

used monomers in this family of compounds include

tetramethylsilane, vinyltrimethylsilane, HMDSO and

hexamethyldisilazane containing Si, H, C, O or N atoms.

HMDSO is a choice of industries because it is a non-toxic

material and no harmful materials are produced during processing.

It can be used in production environment without any

special safety considerations. Basic research studies on plasma

polymerized organosilicones are reviewed by various authors

. The films were found to be amorphous and pinhole free.

Various applications of plasma polymer films include

anticorrosive surfaces, humidity sensors, electrical resistors,

scratch resistance coatings, optical filters, protective coatings,

chemical barrier coatings, etc. Metallized surfaces of

synthetic materials can be protected against corrosion with a

thin polymer layer deposited by plasma polymerization. The

processes can be customized to produce hydrophobic or

hydrophilic (antifogging effect) coatings. Scratch resistant

coatings have been successfully applied on optical lenses but

three-dimensional objects, such as reflectors for the motor car

and lighting industries are complicated by the fact that power

input may not be uniform over the entire substrate surface

during the polymerization process.

A magnetron based plasma polymerization process is described

here with HMDSO as the active ingredient. Deposition

rate, power input, system pressure and chemical analysis

results are discussed.

CONCLUSION

Magnetron Plasma Polymerization results were presented in

this paper with respect to flow rate of monomer, power input,

XPS analysis of the film etc. It seems that the film had Si, O,

C as main elements but target sputtering was present which

added Fe, Cr, Ni and color to the film. Corrosion protection of

the film was also not to the desired level. Another process is

since developed in our labs which provides a better quality

film. In any event, plasma polymerization can be used to

synthesize materials with custom surface chemistries.