Efficient polymerization of a semi-fluorinated liquid crystalline methacrylate

Hoyle, Charles E.; Kang, D.; Jariwala, C.; Griffin, Anselm C.

doi:10.1016/0032-3861(93)90637-p

Cited by 24 publications

(19 citation statements)

References 14 publications

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“…In addition, diblock H(CH 2 ) n (CF 2 ) m F and triblock F(CF 2 ) m (CH 2 ) n (CF 2 ) m F molecules with 4 ≤ n ≤ 14 and m ≥ 6 melt into a smectic B 12 or smectic G 13 mesophase before disordering completely into the isotropic state, − as do the corresponding polymers . Similar small molecules 17 and polymers 18 in which the immiscible segments are connected through ester groups also form smectic mesophases or lamellar crystals, as do aliphatic polyesters, poly(meth)acrylates, poly(α-fluoroacrylate)s, poly(α-fluoroalkoxy)acrylates, and poly(vinyl ether)s 23 with linear fluorocarbon side chains.…”

Section: Introductionmentioning

confidence: 99%

Induction of Smectic Layering in Nematic Liquid Crystals Using Immiscible Components. 1. Laterally Attached Side-Chain Liquid Crystalline Poly(norbornene)s and Their Low Molar Mass Analogs with Hydrocarbon/Fluorocarbon Substituents

1997

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{5-[[[2‘,5‘-Bis[(4‘‘-(n-(perfluoroalkyl)alkoxy)benzoyl)oxy]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-ene}s were polymerized by ring-opening metathesis polymerization in THF at 40 °C using Mo(CHCMe2Ph)(N-2,6- i Pr2Ph)(O t Bu)2 as the initiator. 2,5-Bis[(4‘-(n-(perfluoroalkyl)alkoxy)benzoyl)oxy]toluenes mimic both the phases formed by the poly{5-[[[2‘,5‘-bis[(4‘‘-(n-(perfluoroalkyl)alkoxy)benzoyl)oxy]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-ene}s and the general temperatures of their transitions, and are therefore excellent models of the polymers. In contrast to their hydrocarbon analogs which exhibit only nematic mesophases, all of the polymers and their low molar mass model compounds exhibit smectic C and smectic A mesophases. In both cases, all of the transition temperatures decrease with increasing hydrocarbon length and increase with increasing fluorocarbon length.

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Section: Introductionmentioning

confidence: 99%

Induction of Smectic Layering in Nematic Liquid Crystals Using Immiscible Components. 1. Laterally Attached Side-Chain Liquid Crystalline Poly(norbornene)s and Their Low Molar Mass Analogs with Hydrocarbon/Fluorocarbon Substituents

1997

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“…Many of the results of these investigations have been summarized in reviews. [36][37][38][39] It has been demonstrated that semifluorinated molecules characterized by hydrocarbon and perfluorinated -[CF 2 ]-segments of sufficient length can exhibit structures [40][41][42][43] which have been identified as having smectic ordering over certain temperature ranges which depend on the exact nature of the segments. 40,41 The photoinitiated polymerization of such segmented semifluorinated molecules with polymerizable functional groups 42,43 has been reported.…”

Section: Introductionmentioning

confidence: 99%

“…In one case, polymerization in the smectic phase of a monofunctional methacrylate was shown to exhibit unusually large polymerization rates compared to polymerization in the isotropic phase. 43 The rate increase was suggested to occur because of a decrease in the termination rate constant in the smectic phase.…”

Section: Introductionmentioning

confidence: 99%

Photopolymerization of a Semifluorinated Difunctional Liquid Crystalline Monomer in a Smectic Phase

et al. 1996

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The photoinitiated polymerization of a semifluorinated difunctional monomer, which can exist in both a smectic liquid crystalline phase and an isotropic phase, has been investigated as a function of temperature. Although the maximum rate attained for photoinitiated polymerization in the smectic phase is lower than for polymerization in the isotropic phase, the polymer chain kinetic lifetime is markedly longer in the smectic phase, presumably due to a relatively large decrease in termination rate compared to propagation. The results also suggest that both termination and propagation rate processes are diffusion controlled. By conducting polymerization at a temperature corresponding to the smectic phase of the monomer, it is possible to “lock-in” the order of the smectic phase in the cross-linked network generated.

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“…In fact, if the polymerization is performed in an ordered liquid crystalline phase, the order can be retained throughout polymerization. Additionally, the polymerization rate and molecular weight may increase substantially in ordered phase polymerizations [2]. Although this behavior is not unique to fluorinated monomeric species, the properties exhibited by these materials appear to be considerably different than those of analogous hydrocarbon species.…”

Section: Introductionmentioning

confidence: 98%

Formation of Polymer Stabilized Ferroelectric Liquid Crystals using a Fluorinated Diacrylate

Guymon

Bowman

1999

MRS Proc.

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Ferroelectric liquid crystals (FLCs) have shown great potential for use in electro-optic and display technology due to their inherently fast switching speeds and bistability. Recently, considerable research has been devoted to FLCs mechanically stabilized by a polymer network. The network is formed typically by in situ polymerization of a monomer dissolved in the FLC. Because of the inherent order in the FLC, the polymerization behavior may be significantly different than what might be expected in solution polymerizations. These deviations result largely from the segregation properties of the monomer in the liquid crystal. One class of monomers, namely fluorinated acrylates, is a likely candidate for inducing novel segregation, polymerization and electro-optic behavior in polymer stabilized ferroelectric liquid crystals (PSFLCs). The use of fluorinated moieties has a significant impact on the phase and polymerization behavior of liquid crystal systems. This study focuses on the polymerization of a fluorinated diacrylate, octafluoro 1,6-hexanediol diacrylate (FHDDA), to form PSFLCs and the consequent impact of the polymerization on the ultimate performance. Interestingly, as the temperature is increased and the order of the system decreases, a dramatic increase in the polymerization rate is observed. This increase is especially prominent for polymerizations in the smectic C* phase for which the rate is more than five times that exhibited at much higher temperatures in the isotropic phase. As with other monomer/FLC systems, the segregation of the monomer plays a role in this polymerization behavior as the monomer segregates between the smectic layers of the liquid crystal. The segregation properties also significantly impact the ultimate electro-optic properties. Both ferroelectric polarization and response time of the PSFLC change markedly with different polymerization temperatures, and approach values very close to those of the neat FLC under appropriate polymerization conditions. This behavior not only provides a unique mechanism for rate acceleration in PSFLCs, but also paves the way for new methods to optimize performance in these materials.

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Efficient polymerization of a semi-fluorinated liquid crystalline methacrylate

Cited by 24 publications

References 14 publications

Induction of Smectic Layering in Nematic Liquid Crystals Using Immiscible Components. 1. Laterally Attached Side-Chain Liquid Crystalline Poly(norbornene)s and Their Low Molar Mass Analogs with Hydrocarbon/Fluorocarbon Substituents

Induction of Smectic Layering in Nematic Liquid Crystals Using Immiscible Components. 1. Laterally Attached Side-Chain Liquid Crystalline Poly(norbornene)s and Their Low Molar Mass Analogs with Hydrocarbon/Fluorocarbon Substituents

Photopolymerization of a Semifluorinated Difunctional Liquid Crystalline Monomer in a Smectic Phase

Formation of Polymer Stabilized Ferroelectric Liquid Crystals using a Fluorinated Diacrylate

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