In order to study the effect of glass transition temperature (T g ) on the compression and elastic recovery properties of polymer, several poly(meth)acrylate copolymers having three or four segment units composed of methacrylic acid (MAA) and other vinyl monomers such as glycidyl methacrylate (GMA), styrene (STY), butyl acrylate (BAM), 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), benzyl methacrylate (BzMA), 2-ethylhexyl acrylate (EHA), octadecyl acrylate (ODA), ethyl acrylate (EAM), and lauryl methacrylate(LMA) were synthesized. The synthesized copolymers showed different glass transition temperatures depending on the component type. Thin films and micro patterns were prepared by photolithography process (spin coating=pre-baking=UV-exposure=KOH developing=post-baking) with prepared copolymer solution. The compression and recovery property of copolymer films and micro patterns were determined by nano indenter. As a result, copolymers with lower T g especially MAA=GMA=STY, MAA=GMA=STY=BAM, and MAA=GMA=STY=HEMA copolymers showed higher compression and elastic recovery ratio.

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Spectrum defects such as hot band and rainbow spectra on back light unit (BLU) composed of prism film and diffusing film have been examined by optical analysis. Hot band and rainbow phenomenon could be resulted from rapid luminance decrease and fluctuation in spectra at viewing angles in the range of 30-40 and 50-70 , respectively. By optical simulation with modification in prismatic structure, it is suggested that spectrum defects could be diminished or eliminated in both calculated simulation and practical prism pattern when the plane structure of prism is changed from straight to slow curved.

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The novel photopolymers having photoreactive pendant group were designed and synthesized through the reaction between precursor, poly(methacrylic acid-co-2-hydroxyethyl methacrylate-co-styrene)(poly(MAA-HEMA-STY)) and photoreactive compounds such as methacryloyl chloride (MAC), cinnamoyl chloride (CC), methacryloyl isocyante (MAI) and 3-isopropenyl-a, a-dimethylbenzyl isocyanate (TMI), respectively. The prepared poly(MAA-HEMA-STY) and novel photopolymers were characterized by 1 H-NMR and FT-IR spectroscopy.The photosensitivity of photopolymers was estimated with the UV exposing time by FT-IR spectra change at 1630 cm À1 . The photosensitivity of photoresists was determined by calculating the UV energy at the pattern-remaining step after developing the thin film using gray-scale mask. In connection with the photosensitivity the surface hardness and compression properties of photopolymer films were determined by nano indenter. All prepared photopolymers revealed higher surface hardness than poly(MAA-HEMA-STY). Photopolymers with methacryloyl functional side group showed better photosensitivity than photopolymers with vinyl aromatic and cinnamoyl group. Especially photopolymer prepared from poly-(MAA-HEMA-STY) and MAI showed good potential for the application of negative-working photoresist.