Effect of spacer length on the liquid crystalline property of azobenzene-containing ABA-type triblock copolymers via ATRP

2007 ◽  
Vol 18 (9) ◽  
pp. 1129-1132 ◽  
Author(s):  
Xin De Tang ◽  
Long Cheng Gao ◽  
Xing He Fan ◽  
Qi Feng Zhou
Keyword(s):  
Liquid Crystalline ◽  
Triblock Copolymers ◽  
Spacer Length ◽  
Crystalline Property ◽  
Liquid Crystalline Property

Effect of Spacer Length on the Liquid Crystalline Property of Azobenzene-Containing ABA-Type Triblock Copolymers via ATRP

2010 ◽  
Vol 428-429 ◽  
pp. 67-70
Author(s):  
Xin De Tang ◽  
Long Cheng Gao ◽  
Nian Feng Han
Keyword(s):  
Liquid Crystalline ◽  
Triblock Copolymers ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Spacer Length ◽  
Polymer Main Chain ◽  
Flexible Spacer ◽  
Crystalline Property ◽  
Liquid Crystalline Property ◽  
Methylene Groups

The effect of flexible spacer length on the liquid crystalline property of ABA-type triblock copolymers containing azobenzene groups was investigated. For the study, the monomers, n-[4-(4-ethoxyphenylazo)phenoxy]alkyl methacrylates with varying methylene groups (n = 0, 2, 6) were used to synthesize a series of azobenzene-containing amphiphilic triblock copolymers PAnC-PEG-PAnC by atom transfer radical polymerization (ATRP). Differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and one-dimensional X-ray diffraction (1D WAXD) have shown that the glass transition temperatures of these copolymers decreased as n increases. PA0C-PEG-PA0C has no mesophase, while both PA2C-PEG-PA2C and PA6C-PEG-PA6C have a nematic mesophase. These differences derive of the length of spacer groups between the polymer main chain and side chain.

Influence of the Terminal Substituent of Azobenzene on the Liquid Crystalline Property of ABA Triblock Copolymers

2010 ◽  
Vol 428-429 ◽  
pp. 122-125
Author(s):  
Xin De Tang ◽  
Long Cheng Gao ◽  
Nian Feng Han
Keyword(s):  
Liquid Crystalline ◽  
Triblock Copolymers ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Nematic Mesophase ◽  
Terminal Substituent ◽  
Crystalline Property ◽  
Weight Distributions ◽  
Liquid Crystalline Property

The influence of the terminal substituent of azobenzene on the liquid crystalline property of ABA triblock copolymers was studied. Three kinds of azobenzene-containing monomers with different terminal substituents were respectively used to synthesize ABA triblock copolymers (denoted as PMMAzo12-PEG13-PMMAzo12, PEMAzo14-PEG13-PEMAzo14, and PNMAzo14-PEG13-PNMAzo14) by atom transfer radical polymerization (ATRP). These copolymers were characterized with 1H NMR and GPC, and exhibited controlled molecular weights and narrow molecular weight distributions. Differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) have shown that these copolymers have mesophases. PMMAzo12-PEG13-PMMAzo12 has a smectic mesophase and a nematic mesophase, while both PEMAzo14-PEG13-PEMAzo14 and PNMAzo14-PEG13-PNMAzo14 have a nematic mesophase. This demonstrates that the LC properties of these copolymers highly depend on the terminal substituent of azobenzene.

Synthesis and Liquid Crystalline Properties of Low Molecular Weight Bis-Chalcone Compounds

2021 ◽  
Vol 18 ◽  
Author(s):  
Anju K Sasidharan ◽  
Jomon Mathew ◽  
Ammathnadu S. Achalkumar ◽  
Manoj Mathews
Keyword(s):  
Molecular Weight ◽  
Liquid Crystalline ◽  
Low Molecular Weight ◽  
Aliphatic Chain ◽  
Aromatic Rings ◽  
Property Relationship ◽  
Crystalline Property ◽  
Liquid Crystalline Property ◽  
Mesomorphic Properties ◽  
Structure Liquid

Aim: In this paper, we report on the synthesis and liquid crystalline properties of some low molecular weight bis-chalcone compounds derived from acetone, cyclopentanone and cyclohexanone mesogenic cores. Background: Structurally bis-chalcones belong to a broader family of chalcone compounds. Chalcone is a compound that consists of two aromatic rings linked by an unsaturated objective. Liquid crystalline chalcones are prepared by aliphatic chain substituents on two aromatic rings. Chalcones are well studied for their mesomorphic properties. Compared to a large number of chalcone based LCs reported, only a few articles have been published on the mesomorphic properties of bis-chalcone compounds. The target compounds of the present study varied not only in their central core but also in number and position of terminal aliphatic chain substitutiona key structural unit in deciding the liquid crystalline properties of a compound. Method: All target compounds were synthesized in good yield by base catalyzed Claisen-Schmidt condensation reaction. Molecular structures were confirmed by FT-IR, 1H NMR, 13C NMR, and mass spectroscopic methods. Liquid crystalline property of these compounds was evaluated using polarizing optical microscopy and differential scanning calorimetry. Results: Although none of the acetone based compounds exhibited mesomorphism, cyclopentanone and cyclohexanone based compounds with octyloxy chain at para position on either side of the dibenzylidine ring stabilized liquid crystalline smectic (SmA and SmC) and nematic (N) phases. The observed structure-liquid crystalline property relationship was explained by structural analysis of molecules using DFT calculations. Considering the inherent photoluminescence nature of the chalcone moiety, a preliminary study was carried out on a selected compound to reveal its fluorescence property. Conclusion: Our study brings about an important structure-liquid crystalline property relationship in a relatively unexplored class of bis-chalcone liquid crystals.

scholarly journals Functional poly(phenylacetylene)s carrying azobenzene pendants: Polymer synthesis, photoisomerization behaviors, and liquid-crystalline property

Polymer ◽  
2011 ◽  
Vol 52 (23) ◽  
pp. 5290-5301 ◽  
Author(s):  
Xiao A.-Zhang ◽  
Hui Zhao ◽  
Yuan Gao ◽  
Jiaqi Tong ◽  
Liang Shan ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Polymer Synthesis ◽  
Crystalline Property ◽  
Liquid Crystalline Property
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