Anisotropic networks with stable dipole orientation obtained by photopolymerization in the ferroelectric state

\u3cp\u3eIn this study a ferroelectric liquid crystal (FLC) monoacrylate (S)-4-(1-ethoxycarbonyl-1-ethyloxy)phenyl 4'-(11-acryloyloxyundecyloxy)biphenyl- 4-carboxylate was used. Room-temperature spontaneous polarization of the monoacrylate was measured to be 190 nC/cm\u3csup\u3e2\u3c/sup\u3e. The monoacrylate was provided with 10% LC diacrylate. After inducing macroscopic molecular and dipolar orientation in the ferroelectric phase, polymerization within the reactive system was induced photochemically. In this way an anisotropic polymer network with a spontaneous polarization was produced. Within this network the crosslinks were formed by the diacrylate molecules. The anisotropic network was transparent and highly birefringent. The system showed high thermal stability and remained anisotropic even after being heated to elevated temperatures. The presence of dipolar orientation within the anisotropic networks was characterized by piezoelectric measurements. The piezoelectric coefficient within these networks was found to be highly dependent on the direction of the applied strain. The highest value was measured in the direction perpendicular to the molecular orientation and was 29 pC/N.\u3c/p\u3

Wavelength converting element

\u3cp\u3eA wavelength converting element (110) comprising a polymeric material having a polymeric backbone, the polymeric material comprising a wavelength converting moiety, wherein the wavelength converting moiety is adapted to convert light of a first wavelength to light of a second wavelength, and wherein the wavelength converting moiety is covalently attached to the polymer backbone and/or covalently incorporated into the polymer backbone. The stability and lifetime of wavelength converting molecules comprised in a polymeric material may be improved by covalently attaching the wavelength converting moieties to the polymeric material.\u3c/p\u3

Light-emitting arrangement with organic phosphor

\u3cp\u3eThe invention provides a light-emitting arrangement (100) comprising a light source (105) adapted to emit light of a first wavelength, and a wavelength converting member (106) arranged to receive light of said first wavelength and adapted to convert at least part of the light of said first wavelength to light of a second wavelength, said wavelength converting member comprising i) a carrier polymeric material comprising a polyester backbone comprising an aromatic moiety, and ii) at least one wavelength converting material of a specified general formula. The perylene derived compounds have been found to have excellent stability when incorporated into said matrix material.\u3c/p\u3

Light-emitting arrangement with organic phosphor

\u3cp\u3eThe invention provides a light-emitting arrangement (100) comprising a light source (105) adapted to emit light of a first wavelength, and a wavelength converting member (106) arranged to receive light of said first wavelength and adapted to convert at least part of the light of said first wavelength to light of a second wavelength, said wavelength converting member comprising i) a carrier polymeric material comprising a polyester backbone comprising an aromatic moiety, and ii) at least one wavelength converting material of a specified general formula. The perylene derived compounds have been found to have excellent stability when incorporated into said matrix material.\u3c/p\u3

Linear polarizers based on polymer blends:oriented blends of poly(ethylene-2,6-naphthalenedicarboxylate) and a poly(styrene/methylmethacrylate) copolymer

\u3cp\u3eThe optical properties of linear polarizers based on blends of poly(ethylene-2,6-naphthalenedicarboxylate) and a poly(styrene/methylmethacrylate) copolymer are presented. In the oriented blends, the refractive index of the dispersed phase is matched with the ordinary refractive index of the birefringent continuous phase while, a large refractive index mismatch is simultaneously generated in the perpendicular direction. The films are therefore transparent or opaque depending on the polarization direction of the incident light and act as a linear polarizer. In the non transparent state, the incident light is mainly scattered in the backward direction (+80%), which potentially enhances the yield of transmitted polarized light if the backscattered light is recycled in a suitable device. This latter feature is useful, for instance, in display applications where a high brightness or energy efficiency is desired.\u3c/p\u3

Observation of blue phases in chiral networks

\u3cp\u3eWe report the first observation of cholesteric blue phases in chiral anisotropic polymer networks. In two-component mixtures of a chiral and a non-chiral diacrylate, we observed typical textures of BPI, BPII and BPIII phases. By photopolymerization of these materials at constant temperature we obtained blue phase networks. After polymerization, the blue phases were stored, which enabled us to further study them without any temperature control.\u3c/p\u3

Wavelength converting element

\u3cp\u3eA wavelength converting element (101, 102, 103, 110) comprising a polymeric carrier material comprising a first wavelength converting material adapted to convert light of a first wavelength to light of a second wavelength, wherein the oxygen diffusion coefficient (D) of the polymeric carrier material is 8×10−13 cm2/s or less at 25° C. A prolonged lifetime of the wavelength converting material is achieved by selecting a polymeric carrier material with an oxygen diffusion coefficient (D) at 8×10−13 cm2/s or less at 25° C.\u3c/p\u3

Wavelength converting element

\u3cp\u3eA wavelength converting element (101, 102, 103, 110) comprising a polymeric carrier material comprising a first wavelength converting material adapted to convert light of a first wavelength to light of a second wavelength, wherein the oxygen diffusion coefficient (D) of the polymeric carrier material is 8 x 10-13 cm2/s or less at 25°C. A prolonged lifetime of the wavelength converting material is achieved by selecting a polymeric carrier material with an oxygen diffusion coefficient (D) at 8x10-13 cm2/s or less at 25°C.\u3c/p\u3