Optical Adhesive Polymers

UV hardening resin was first reported in 1968. From the report, UV hardening resins have been applied to many industrial fields, such as wood coating, electronic equipment, printing inks, and adhesive reagents. UV adhesive resin is one of the most important applications of UV hardening. The merits of UV adhesive resins are  

High speed in curing because of photo-hardening 

Those merits are good characteristics for optical systems. Epoxy is a superior material for UV curing. The ring-opening reaction of epoxy is shown in Equation (5.1)  

Hydrogen bond between adhesive material and glass plate. 

a radical initiates polymerization of methacrylate. Methacrylates are also polymerized by an ion initiator as follows  

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Novel, flexible, completely organic, polymer dispersed liquid crystal (PDLC) "light valves" were fabricated using two flat pieces of commercial overhead transparency substrates (Nashua j -20) coated with polypyrrole between which a film of commercial PDLC material (Norland Products Co. NOA 65 optical adhesive and BDH Ltd. E7 liquid crystal fluid together with EM. Ind. 15 micron polystyrene spacers) was sandwiched. The optical adhesive was polymerized by exposure to UV light. Thin conducting polypyrrole films of varying controllable thickness were deposited on the overhead transparency. 

An ideal adhesive film system can be made by the method originally used by Roberts, shown in Fig. 14.4(a). He moulded gum rubber against an optically smooth surface such as glass, crosslinked the polymer by heating with sulfur or peroxide, peeled the rubber from the surface to reveal an optically smooth polymer surface, then adhered this material to another smooth surface to form the joint. Alternatively, low temperature reacting materials such as silastomers or... 

NOA65 (Norland Optical Adhesive 65) is a commonly used photocurable polymer because its refractive index tip 1.52) is close to the tio of many commercial LC mixtures. Before U V curing, NOA65 is a clear and colorless liquid. The measurement of the monomer is fairly simple. However, in a practical device, such as a PDLC, all the monomers are cured to form a polymer... 

Norland Optical Adhesive (NOA63) Perfluorosulfonic acid polymer (PFSA, 3 M Corporation)/poly(acrylic acid) (PAA)/sulfonated octaphenyl polyhedral silsesquioxane (sPOSS) with weight ratio of 65 5 35 0.498 (120 °C, 90 % RH) [88]... 

HP is chemically a three-carbon, optically inactive, specialty chemical with commercial interest. It is the structural isomer of lactic acid (Kxunar et al., 2013). It can be used as an intermediate for the synthesis of other important chemicals, such as malonic acid, 1,3-propanediol (PDO), acrylonitrile, acrylic acid, and acrylamide. These compounds are used for making adhesives, polymers, fibers, plastic packing, resins, and cleaning agents, as listed in Fig. 6.1.3-HP acts as a starting material for the synthesis and production of poly-3-hydroxy... 

The refractive index is one of the important optical properties in focus for nanocomposite research at present. Most of the conventional polymers show refractive indices between 1.3 and 1.7 only few polymers exhibit higher refractive indices such as polythiophene with n = 2.12. With the current development of optoelectronic applications the need to adjust the refractive index of polymeric materials is higher than ever before. Potential applications range from creating novel composite lenses for charged coupled devices, optical filters, or reflectors to optical waveguides, optical adhesives or encapsulants, antireflection films, or integration in improved efficiency solar cells. 

To make a the photo-tailorable SMP (PT-SMP), a commercially available UV curable polymer (Norland Optical Adhesive (NOA) 63, Norland Products, Inc.) was cured using a high intensity ultraviolet lamp (365 nm, Spectronics Corporation, Model SB-1 OOP) isolated with a box for safety. To prepare smooth PT-SMP films, two quartz plates (2 cm x 3 cm) were employed to form the top and bottom mold surfaces with a spacer (1.5 mm thickness) being placed between the plates. A distance separating the UV lamp and the mold was set at 5 cm. After curing for prescribed periods of time, crosslinked PT-SMP samples were removed from the quartz substrate by placement on a hot plate heated to 70 °C, a temperature allowing convenient pealing away of the film from the mold. 

Thin sheets of mica or polymer films, which are coated with silver on the back side, are adhered to two cylindrical quartz lenses using an adhesive. It may be noted that it is necessary to use an adhesive that deforms elastically. One of the lenses, with a polymer film adhered on it, is mounted on a weak cantilever spring, and the other is mounted on a rigid support. The axes of these lenses are aligned perpendicular to each other, and the geometry of two orthogonally crossed cylinders corresponds to a sphere on a flat surface. The back-silvered tbin films form an optical interferometer which makes it possible... 

Israelachvili and coworkers [64,69], Tirrell and coworkers [61-63,70], and other researchers employed the SFA to measure molecular level adhesion and deformation of self-assembled monolayers and polymers. The pull-off force (FJ, and the contact radius (a versus P) are measured. The contact radius, the local radius of curvature, and the distance between the surfaces are measured using the optical interferometer in the SFA. The primary advantage of using the SFA is its ability to study the interfacial adhesion between thin films of relatively high... 

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