Evaluation of high temperature polymers in nanolayered films and gradient refractive index (GRIN) lenses

Abstract

A new polymer nanolayer gradient refractive index (GRIN) system with more robust thermal stability because of incorporation of a high glass transition temperature polyester, OKP4HT, was demonstrated. A combination of extruded nanolayered GRIN film systems, comprised of five unique polymer materials, were combined to produce laminate optics comprised of a large internal refractive index gradient distribution, n 5 1.445 -1.630, without degradation of optical transmissive properties. The optical performance of a series of varied magnitude GRIN lenses, ranging from Dn 5 0 to 0.185, was evaluated. Increasing the lens refractive index range resulted in decreased optic sphericalaberrations that followed analytical predictions. An analytical approach was reported to correlate the polymer material upper service temperature (UST) to the onset of polymer material loss modulus as measured by DMTA. Thermo-optical interferometry measurements of irreversible lens deformation confirmed the lenses UST at 1258C for the OKP4HT/ PC system as compared to 758C for a PMM/SAN17 system.

Soft Functionally Gradient Materials and Structures – Natural and Manmade: A Review

“…While a small transverse gradient span is desirable in many current applications (optics, bio-analytics, thermal management, etc. ), [32,168,196] improved fabrication routes are required to prepare FGMs with larger, axial, and directionally complex gradients necessary for newer or advanced applications. In general, complex geometries are either too time-consuming or difficult to manufacture by conventional processes.…”

“…Polymeric OGMs are prepared through several diffusion-based techniques such as diffusion copolymerization, [153,164,165] extrusion copolymerization, [166][167][168] interfacial gel copolymerization, [169][170][171] photo-copolymerization, [146,172,173] centrifugal diffusing polymerization, [148,166,168] suspension polymerization, [174,175] etc. For a given set of iso-index materials, the difference in respective RI defines the magnitude of the gradient, [148,166,168] and the difference in densities determines the direction of the gradient. [176,177] In a study by Duijnhoven and Bastiaansen, radial OGM was obtained by the spatial distribution of polymers under centrifugal force.…”

“…GRIN prepared by inter-diffusion involves either the exchange of ions at the surface of inorganic glass immersed in an ionic bath [149,150,152] (see Figure 6a), or diffusion of miscible monomers/pre-polymer solutions having different RI, [12,153,163] respectively. Polymeric OGMs are prepared through several diffusion-based techniques such as diffusion copolymerization, [153,164,165] extrusion copolymerization, [166][167][168] interfacial gel copolymerization, [169][170][171] photo-copolymerization, [146,172,173] centrifugal diffusing polymerization, [148,166,168] suspension polymerization, [174,175] etc. For a given set of iso-index materials, the difference in respective RI defines the magnitude of the gradient, [148,166,168] and the difference in densities determines the direction of the gradient.…”

Physical coloring of multilayered polymeric structures

“…Several polymer pairs were characterized in a multilayered structure for enhanced mechanical properties, permeability reduction and tunable optics , including a TPU/PEBAX pair that could be stretched to shift the reflected wavelength . Multilayer systems for a variety of uses have become popular and accessible such as effective light emitters , distributed Bragg reflector resonators and gradient refractive index lenses . In this work, alternate structures of two transparent TPUs were coextruded at low shear rates.…”