Abstract

We report second harmonic generation measurements on multilayers of two interleaved mainchain polymers fabricated by Langmuir Blodgett (LB) deposition. LB processing¹ offers advantages over electric-field poling in that it can be done at room temperature (hence the kT Brownian motion is much less) without the strong electric fields that can lead to film damage during corona poling. Mainchain polymers are inherently more stable than sidechain polymers because both ends of the chromophore are attached to the backbone of the polymer, whereas only one end of the chromophore is attached to the backbone in a sidechain polymer, and the other end is dangling free at one of the interfaces of each monolayer. Furthermore, only mainchain polymers that contain the chromophore in a head-to-head (syndioregic) configuration can have the chromophores ordered normal to the plane of the film by hydrophilic/hydrophobic forces. This is because a mainchain polymer containing chromophores in a heat-to-tail configuration will probably have all of the chromophores lying on the water, in the plane of the film with opposing dominant hyperpolarizability components.

© 1995 Optical Society of America