Synthesis of side chain liquid crystal polymers by living ring-opening metathesis polymerization. 5. Influence of mesogenic group and interconnecting group on the thermotropic behavior of the resulting polymers

A new homologous series of SCLCPs containing the 4‐cyanobiphenyl mesogenic group attached to the polymaleimide backbone through paraffinic spacers of two to eight methylene units have been prepared. All the polymers exhibit liquid crystalline behavior; specifically SAd‐ (or SC‐) like and nematic phases are observed. The glass transition temperature decreases from 150 to 43°C on increasing spacer length. The isotropization temperatures exhibit an odd–even effect on varying the length and parity of the spacer, in which the odd members exhibit the higher values. This is attributed to the change in the average shape of the side chain as the parity of spacer is varied. The isotropization temperatures (>300–120°C) and the mesophase thermal stabilities (190–60°C) are high. Comparison is made with polymers containing the same mesogenic group attached to backbones of decreasing rigidity. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2531–2546, 1998

Section: Experimental Materialsmentioning

confidence: 99%

Section: Thermal Behavior Of M N and Pm N (N ‫؍‬ 2-8)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis and characterization of polymaleimides containing 4-cyanobiphenyl-based side groups for nonlinear optical applications

Gaṅgādhara

Noël

Thomas

et al. 1998

“…[1][2][3][4][5][6][7][8] In the polynorbornene series, the liquid crystallinity of polymers containing 4Ј-methoxybiphenyl-4-yloxy and 4-cyanobiphenyl-4Ј-yloxy mesogenic groups was correlated with spacer length, molecular weight, and molecular weight distribution. [1][2][3][4][5][6] However, because it is difficult to control the optical purity of the monomer and the regio-and stereo-specificity of the ROMP, there are few investigations 4 determining the influence of backbone microstructure which can exhibit head (H)/tail (T) isomerism, cis/trans double bond isomerism, and ring tacticity. It can be noted that those structural features can afford up to 16 different dyads (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of 4-cyanobiphenyl-4?-yloxy-functionalized poly(7-oxanorbornene-5,6-exo-dicarboximide)s via ring opening metathesis polymerization (ROMP)

Gaṅgādhara¹,

Campistron²,

Thomas³

et al. 1998

N‐[n‐(4‐cyanobiphenyl‐4′‐yloxy)alkyl]‐7‐oxanorbornene‐5,6‐exo‐dicarboximide (CBON2–CBON8) with increasing number of methylene groups in the alkyl part (n = 2–8) were synthesized by Mitsunobu condensation between the appropriate alcohols (CBA2–CBA8) and 7‐oxanorbornene‐5,6‐exo‐dicarboximide (ON). The conditions for the ring opening metathesis polymerization of CBONn giving acceptable molecular weights and molecular distributions were established. Characterization of the resulting polymers (P2–P8) by 1H‐ and 13C‐NMR has shown a high trans content. Differential scanning calorimetry and optical microscopy analysis have shown that the alcohols CBAn are thermotropic with some variations between the first and second heating‐cooling cycles, the monomers CBONn melt with no evidence of any mesomorphic state, the polymers Pn show only the glass transition, and the glass transition temperature (Tg) decreases with increases in the spacer length. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2807–2821, 1998

“…Thus, if optically resolved monomer is obtained, it would be of great interest to evaluate polymerization behavior for the enantiomerically pure norbornene derivatives bearing both cyano and ester groups. Although Schrock and coworkers reported the synthesis of substituted polynorbornenes, [33][34][35][36][37][38][39][40] to the best of our knowledge, the influence of the main chain microstructure on the optical behavior of exo-2,3-disubstituted polynorbornenes has not been investigated very intensively to date.…”

mentioning

confidence: 99%

Enantioseparation of doubly functionalized polar norbornenes by HPLC and their ruthenium‐catalyzed ring‐opening metathesis polymerization

Nishihara

Doi

Izawa

et al. 2009

Doubly fuctionalized polar norbornenes bearing the cyano and ester groups in 2,3‐positions are synthesized and enantiomers are separated by high performance liquid chromatography (HPLC) with a chiral stationary phase. These optically active monomers are polymerized by ruthenium carbene catalysts, and high yields of the polymers were obtained. The chiral monomer bearing ethyl ester gave an optically active polymer of lower, but opposite sign of optical rotation (monomer [α]D = +61.0°, polymer [α]D = −3.1°). The circular dichroism (CD) of the obtained chiral polymers gave a Cotton effect. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 485–491, 2010