TY - JOUR
T1 - Effect of trifluoromethyl substituents on birefringence of polystyrene
AU - Tagaya, Akihiro
AU - Koike, Kotaro
AU - Koike, Yasuhiro
AU - Okamoto, Yoshiyuki
N1 - Funding Information:
This work was partly supported by the Japan Society for the Promotion of Science (JSPS) through its “Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program).” The authors would like to thank Ms. Megumi Kurihara for the birefringence and IR measurements of the CF3-substituted polystyrenes and Mr. Hikaru Hotta for those of PSt.
Publisher Copyright:
Copyright © 2016 John Wiley & Sons, Ltd.
PY - 2017/8
Y1 - 2017/8
N2 - Transparent thermoplastic polymers that exhibit no birefringence are ideal for optical components such as optical films for liquid crystal displays and various lenses. Copolymerization of a positive birefringent monomer with a negative monomer is an effective technique for obtaining low birefringent polymers, especially zero-photoelastic birefringence polymers that exhibit no photoelastic birefringence even during elastic deformation. We prepared four types of trifluoromethyl-substituted polystyrenes. By substituting hydrogens at the ortho or meta positions of the benzene ring of polystyrene, we demonstrated that poly(2-(trifluoromethyl)styrene), poly(3-(trifluoromethyl)styrene), and poly(3,5-bis(trifluoromethyl)styrene) had negative photoelastic coefficients. However, poly(4-(trifluoromethyl)styrene) had a positive photoelastic coefficient similar to that of polystyrene. Based on these results, we synthesized a zero-photoelastic birefringence polymer of poly(2-(trifluoromethyl)styrene-co-4-(trifluoromethyl)styrene) (55/45 wt.) exhibiting no photoelastic birefringence in elastic deformation, in which the positive photoelastic birefringence of the poly(4-(trifluoromethyl)styrene) unit was compensated for by the negative photoelastic birefringence of the poly(2-(trifluoromethyl)styrene) unit. The discovery of polymers having negative photoelastic coefficients is valuable for the design and synthesis of zero-photoelastic birefringence polymers. The four types of trifluoromethyl-substituted polystyrenes are promising optical materials because they have high transparency (transmittance > 89–92% for 27–34-µm thickness films) in the visible and near-infrared regions and a high decomposition temperature of approximately 400°C.
AB - Transparent thermoplastic polymers that exhibit no birefringence are ideal for optical components such as optical films for liquid crystal displays and various lenses. Copolymerization of a positive birefringent monomer with a negative monomer is an effective technique for obtaining low birefringent polymers, especially zero-photoelastic birefringence polymers that exhibit no photoelastic birefringence even during elastic deformation. We prepared four types of trifluoromethyl-substituted polystyrenes. By substituting hydrogens at the ortho or meta positions of the benzene ring of polystyrene, we demonstrated that poly(2-(trifluoromethyl)styrene), poly(3-(trifluoromethyl)styrene), and poly(3,5-bis(trifluoromethyl)styrene) had negative photoelastic coefficients. However, poly(4-(trifluoromethyl)styrene) had a positive photoelastic coefficient similar to that of polystyrene. Based on these results, we synthesized a zero-photoelastic birefringence polymer of poly(2-(trifluoromethyl)styrene-co-4-(trifluoromethyl)styrene) (55/45 wt.) exhibiting no photoelastic birefringence in elastic deformation, in which the positive photoelastic birefringence of the poly(4-(trifluoromethyl)styrene) unit was compensated for by the negative photoelastic birefringence of the poly(2-(trifluoromethyl)styrene) unit. The discovery of polymers having negative photoelastic coefficients is valuable for the design and synthesis of zero-photoelastic birefringence polymers. The four types of trifluoromethyl-substituted polystyrenes are promising optical materials because they have high transparency (transmittance > 89–92% for 27–34-µm thickness films) in the visible and near-infrared regions and a high decomposition temperature of approximately 400°C.
KW - copolymerization
KW - orientational birefringence
KW - photoelastic birefringence
KW - polystyrene
KW - trifluoromethyl substituents
UR - http://www.scopus.com/inward/record.url?scp=84969972190&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84969972190&partnerID=8YFLogxK
U2 - 10.1002/pat.3825
DO - 10.1002/pat.3825
M3 - Article
AN - SCOPUS:84969972190
SN - 1042-7147
VL - 28
SP - 994
EP - 999
JO - Polymers for Advanced Technologies
JF - Polymers for Advanced Technologies
IS - 8
ER -