Ferroelectric liquid crystalline polysiloxanes with high spontaneous polarization and possible applications in nonlinear optics

Kapitza, Heinrich; Zentel, Rudolf; Twieg, Robert J.; Nguyen, Cattien V.; Vallerien, S. U.; Kremer, Friedrich; Willson, C. Grant

doi:10.1002/adma.19900021106

Cited by 90 publications

(32 citation statements)

References 21 publications

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“…The second-order nonlinear optical properties of organic polymers are also well documented (9,(11)(12)(13)(14)(15). For a material to exhibit significant second-order nonlinear optical responses it must have a noncentrosymmetric structure.…”

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confidence: 97%

“…However, the details of the crucial interplay of chemical, stereochemical and electronic factors in effecting the structures and properties of chiral supermolecular assemblies are still far from being elucidated (9,17,18).…”

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confidence: 99%

“…The ferroelectric properties of the chiral smectic C* mesophase are recognized in a number of thermotropic polymers (4)(5)(6)(7)(8)(9). In this mesophase the optically active mesogens with high spontaneous polarization are assembled in a layered, helical superstructure which must then be untwisted into another superstructure with a resulting macroscopic electric polarization allowing switching bistability.…”

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confidence: 99%

“…Electric field poling of polymers containing a dipolar chromophore is a common method to introduce a polar axis into the LC medium, and the consequently reduced orientational averaging of molecular dipoles allows for a net secondorder susceptibility to result. An alternative approach to originating noncentrosymmetry might be to introduce chirality and the other structural requirements of the ferroelectric smectic C* phase into a polymeric structure containing chromophores capable of producing a nonlinear response without poling in an external electric field (9,16).…”

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confidence: 99%

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Chiral Liquid-Crystalline Copolymers for Electrooptical Applications

Chiellini

Galli

Angeloni

et al. 1992

ACS Symposium Series

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The synthesis and liquid crystalline properties of four new series of copolymers consisting of variously substituted azobenzene mesogenic groups are presented. While three series contain chiral, optically active counits, the fourth series contains achiral dipolar chromophore counits. The incidence and stability of different chiral (nematic and smectic) mesophases are discussed with relevance to their potential ferroelectric and nonlinear optical properties. These samples may serve as models of liquid crystalline polymers to be used in electrooptical applications.Liquid crystalline (LC) polymers present a unique combination of the characteristics peculiar to liquid crystals with those typical of polymers. While the former include molecular polarizability, self-assembly tendency, diversity of structures, and fast response to external electric or magnetic fields, the latter can feature variety of molecular architectures, dimensional stability, mechanical orientability, and ease of processability (1). The introduction of chirality in the molecular structure of LC materials induces the formation of chiral nematic (cholesteric) or chiral smectic supermolecular assemblies endowed with a macroscopic twist superposed on them (2).This consistently offers an additional valuable means of tuning the liquid crystal behavior and addressing specific responses of chiral LC polymers in optics and electrooptics. In this context, the ferroelectric and nonlinear optical properties of side chain LC polymers are currently the focus of intense research (3).The ferroelectric properties of the chiral smectic C* mesophase are recognized in a number of thermotropic polymers (4-9). In this mesophase the optically active mesogens with high spontaneous polarization are assembled in a layered, helical superstructure which must then be untwisted into another superstructure with a resulting

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confidence: 97%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Chiral Liquid-Crystalline Copolymers for Electrooptical Applications

Chiellini

Galli

Angeloni

et al. 1992

ACS Symposium Series

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“…When conventional mesogenic groups in linear crystalline polymers (LCPs) are replaced by chiral mesogens, ferroelectric liquid crystalline polymers (FLCPs) are obtained [140][141][142]. FLCPs are regarded as important species for optical switching and electrooptical applications [143,144].…”

Section: Scheme 12mentioning

confidence: 99%

Polyester Dendrimers

Twibanire

Grindley

2012

Polymers

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Polyester dendrimers have been comprehensively reviewed starting from their first synthesis in the early 1990s by Hawker and Fréchet. Polyester dendrimers have attracted and continue to attract extensive interest because they are comparatively easy to make and because, whenever they have been tested, they have been found to be non-toxic. A number of different strategies for their synthesis have been examined and the methods employed for formation of the ester bond during dendrimer assembly have been summarized. The newest approaches, including the use of bifunctional orthogonally reacting dendrons and accelerated synthesis have been surveyed.

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