Dielectric relaxation of liquid crystalline dendrimers and liquid crystalline polymers with pendant nitro groups

Örtegren, Jonas; Tidlund, J.; Nykvist, M.; Busson, P.; Hult, Anders; Sen, Sudeepto; Boyd, R. H.; Gedde, Ulf W.

doi:10.1016/s0032-3861(01)00558-4

Cited by 4 publications

(1 citation statement)

References 27 publications

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“…Second, a novel type of dendritic polyols, G1‐(OH) 4 and G2‐(OH) 8 , owning hydroxyl peripheries other than amine peripheries of PPI or PAMAM, were synthesized according to a two‐step procedure. As a consequence of the attachment of these polyols with vinyl‐terminated promesogens using a stable covalent ester linkage, which was rarely reported in SC‐LCDs,54–57 side‐chain dendrimers G1‐(MU) 4 and G2‐(MU) 8 bearing four or eight promesogenic units were obtained without incorporation of any promoting group. The mesogenic behaviors of these two dendrimers were then investigated by a combination of analytical techniques such as differential scanning calorimeter (DSC), polarized optical microscope (POM), and X‐ray diffraction (XRD).…”

Section: Introductionmentioning

confidence: 99%

Vinyl‐terminated liquid‐crystalline dendrimers based on dendritic polyols and their siloxane‐based elastomers

Lin

Sun

2012

J. Polym. Sci. A Polym. Chem.

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A new series of side-chain liquid-crystalline dendrimers (LCDs) by grafting vinyl-terminated phenyl benzoatebased promesogens to a novel polypropyleneimine-derived dendritic polyols are reported. Polarized optical microscopy and X-ray diffraction studies show that both the compounds display a smectic-A (SmA) mesophase. The second-generation dendrimer bearing eight-branched promesogens exhibits a more stable SmA mesophase with a wide mesomorphic temperature range. It is demonstrated that ''promoting groups'' in the structure of LCD for the enhancement of mesomorphic stability are unnecessary in the case of strong anisotropic interactions. In contrast to conventional LCDs, these two compounds possess reactive vinyl terminals that endow them with the potential for the preparation of polymeric materials. For the first time, a type of thermoset elastomers is explored from LCDs via hydrosilylation crosslinking reaction of vinyl terminals and siloxane crosslinker. Two-dimensional X-ray diffraction study indicates that the lamellar structures of original dendrimers are reserved in the elastomer networks. Stress-strain curves reveal that these elastomers exhibit excellent elasticity under successive uniaxial compression. The combination of anisotropic structures of rigid units and elasticity of flexible networks in this novel series of elastomers makes them promising candidates for the application in artificial muscles or cartilages.

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Section: Introductionmentioning

confidence: 99%