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  • Thermo-optic coefficient of polyisobutylene ultrathin films measured with integrated photonic devices.

Thermo-optic coefficient of polyisobutylene ultrathin films measured with integrated photonic devices.

Langmuir : the ACS journal of surfaces and colloids (2011-11-25)
Hong Seok Choi, Dania Neiroukh, Heather K Hunt, Andrea M Armani
ABSTRACT

The optical properties of polymeric materials, such as transmission loss and the thermo-optic coefficient, determine their utility in numerous applications, ranging from nanotechnology to the automotive and aerospace industries. However, because of the wide variation in the physical properties of polymers, many are unsuited for characterization using conventional techniques; consequently, their optical properties are unknown. One such polymer is polyisobutylene, which is viscous at room temperature and therefore is not compatible with conventional transmission loss and the thermo-optic coefficient characterization techniques because they rely on contact measurements. To overcome this, we have developed an integrated, microscale optical sensor that relies on an evanescent wave to study the material's optical behavior. Using this device, we successfully determined the refractive index, the transmission loss, and the thermo-optic coefficient of ultrathin films of polyisobutylene. The films are deposited on the sensor's silica surface using either spin coating or surface-initiated cationic polymerization, demonstrating the flexibility of this approach.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Polyisobutylene, average Mw ~1,000,000, average Mn ~600,000 by GPC/MALLS, average Mv ~1,200,000
Sigma-Aldrich
Polyisobutylene, average Mw ~500,000, average Mn ~200,000 by GPC/MALLS, average Mv ~420,000