Synthesis of a Zero-Birefringence Optical Polymer by the Birefringent Crystal DopantMethod

Abstract

Birefringence induced by the orientation of polymer main chains during an injectionmolding or extrusion processing restricts the application of optical polymers to optical devices that require maintaining the polarization state of incident light. We propose the “birefringent crystal dopant method” to compensate the birefringence of polymers by homogeneous doping with an opposite birefringent needle-like crystal. Strontium carbonate (SrCO3) was selected for this method and synthesized, with particle lengths of 50-200nm and aspect ratios of 2-5. SrCO3 was doped into poly(MMA/BzMA= 78/22(wt./wt.)) film. The film was uniaxially drawn at 130°C and 4mm/min. For the first time, the positive birefringence of the drawn copolymer film at a wavelength of 633nm was compensated by doping with 0.3wt.% of SrCO3 without losing transparency and thermostability.

Sulfur-Rich Polyimides Containing Bis(3-(trifluoromethyl)phenyl)thiophene for High-Refractive-Index Applications

“…Polymer 13 C NMR (CDCl 3 ): δ 166.5 and 166.4 (14,15), 164.0 (18), 152.7 (22), 147.6 (25), 142.3 (2), 134.6 (6), 134.2 (7), 134.1 (16), 134.0 (13), 132.9 (3), 132.7 (12), 131.6 (10), 130.8 (q, 2 J CF = 30.7 Hz; 5), 128.9 (8), 128.8 (24), 127.2 (11), 125.9 (20), 125.4 (1), 124.9 (21), 123.8 (q; 4), 123.4 (q, 1 J CF = 274 Hz; 9), 123.2 (19), 120.0 (23), 111.9 (17), 42.6 (26), 31.0 ppm (27). 19 16), 131.2 (q, 2 J CF = 30.5 Hz; 5), 130.9 (10), 129.0 (8), 127.1 (11), 125.5 (1), 125.4 (17), 124.2 (20), 123.8 (q; 4), 123.4 (q, 1 J CF = 275 Hz; 9), 123.3 (q, 1 J CF = 288 Hz; 23), 65.3 ppm (sept, 2 J CF =26 Hz; 22). 19 F NMR (CDCl 3 ): δ −62.1 (9), −64.4 ppm (23).…”

“…13 C NMR (DMF-d 7 )� data of CH carbons determined from the heteronuclear single quantum correlation (HSQC) spectrum: δ 135.2 (7) (11,12), 7.59 ppm (7). 13 C NMR (DMF-d 7 )�data of CH carbons determined from the HSQC spectrum: δ 135.3 (7), 134.8 (19), 131.9 (11), 129.8 (8), 128.5 (12), 127.3 (1), 125.0 (20), 123.7 (4), 123.0 ppm (17). 19 F NMR (DMF-d 7 ): δ −61.4, −61.8 ppm.…”

“…Performances of optical devices are usually compromised due to high birefringence values, often requiring modifications in lenses or polarization states of the incident light. 17 Birefringence is the difference between the in-plane (parallel to the molecular axis) and out-of-plane (perpendicular to the molecular axis) refractive indices of the polymer, and it depends on the molecular structure of the polymer repeat unit and the processing history of the polymer. 18 One useful method to decrease the birefringence of the polymer is to design the repeat unit structure in such a way that the polymer chain orientations are random, with flexible chains or bulky groups perpendicular to the polymer backbone.…”

“…Along with a high value of n , it is also necessary to produce polymer films with low birefringence. Performances of optical devices are usually compromised due to high birefringence values, often requiring modifications in lenses or polarization states of the incident light . Birefringence is the difference between the in-plane (parallel to the molecular axis) and out-of-plane (perpendicular to the molecular axis) refractive indices of the polymer, and it depends on the molecular structure of the polymer repeat unit and the processing history of the polymer .…”

High refractive index polymers: fundamental research and practical applications

“…For instance, the high birefringence of one optical polymer often degrades the performance of optical devices that require focusing by lenses or maintaining the polarization state of incident light. 27 The birefringence of one polymer is defined as the difference between the in-plane (parallel to the molecular axis, n TE ) and out-of-plane (perpendicular to the molecular axis, n TM ) refractive index of the polymer. The birefringence originates from two main sources: the inherent molecular structure and the processing history of the polymer.…”