Side-Chain Liquid Crystalline Poly(meth)acrylates with Bent-Core Mesogens

Chen, Xiaofang; Tenneti, Kishore; Bai, Yaowen; Wan, Xinhua; Fan, Xinghe; Zhou, Qifeng; Rong, Lijian; Hsiao, Benjamin S.

doi:10.1021/ma061949u

Cited by 38 publications

(43 citation statements)

References 45 publications

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“…Schematic Representation of the Shear Geometry BP molecule has a contour length of ∼3.3 nm, we propose that each smectic layer consists of two layers of BP molecules forming a bilayer structure (SmA 2 ), similar to a few other bentcore LC polymers reported. 34,43 The smectic layer scattering arcs are weak, possibly due to the low concentration of the BP molecules. Note that pure BP molecules do not exhibit LC behavior.…”

Section: Resultsmentioning

confidence: 99%

Hierarchical Nanostructures of Bent-Core Molecules Blended with Poly(styrene-b-4-vinylpyridine) Block Copolymer

et al. 2007

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We report the phase structures observed in blends of poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) and a bent-core molecule 1-[4′-(3′′,4′′,5′′-tridecyloxybenzoyloxy)phenyleneoxycarbonyl]-3-[(4′-hydroxyphenyl)oxycarbonyl]benzene (BP). Hydrogen bonding between the terminal -OH group of BP and pyridine of P4VP led to the formation of P4VP(BP) n complex, which exhibited liquid crystalline (LC) order. This LC ordering, combined with microphase separation of the BCP, led to the formation of hierarchical nanostructures. The phase structures of the blend samples were investigated as a function of the concentration of BP using small-angle and wide-angle X-ray scattering and transmission electron microscopy techniques. By increasing the BP content, BCP phase morphology transformed from lamellae to cylinders. In the two cases investigated, the P4VP/BP complex formed a bilayer smectic A LC structure within the BCP domains, and these layered structures were oriented perpendicular to the BCP interface. A detailed structural and morphological study will be reported. IntroductionHierarchical nanostructures, usually spanning from the molecular scale (sub-nanometers) to hundreds of nanometers, are of great technological importance. Block copolymers (BCPs) provide one of the most straightforward templates to achieve hierarchical nanostrucutres. 1 BCP microphase separation could lead to the formation of a variety of structures such as lamellae, cylinders, gyroid, and spheres. 2 The length scale of these phase separated structures is ∼10-50 nm. Amorphous BCP (coilcoil) phase structures have been extensively investigated. 2,3 Tuning the chemical structure of one or several segments of the BCP leads to the possibility of forming a secondary structural order within the BCP domains. To this end, a few types of BCP systems have been proposed, including crystalline-amorphous (or crystalline-crystalline) BCPs 4-8 and liquid crystalline (LC) BCPs. 9-20 In the first case, polymer chains crystallize in the confined (soft or hard confinement) space that is formed by the BCP microphase separation. Structural hierarchy can be achieved due to the ordered structure formation at two different length scales as a result of BCP microphase separation (10-50 nm) and the crystalline structure formation (1-10 nm). In the second case, LC or LC polymers are used as one BCP block. LCs form ordered structures on the 1-10 nm length scale. Thus, LC BCPs represent a natural hierarchical-structure-forming system. The structural flexibility of LC also enables incorporating functionalities into BCP microdomains. A number of LC BCPs have been investigated. Depending on the LC molecular architecture, LC BCPs can be divided into side-chain LC-BCPs, 9,[12][13][14]20 main-chain LC-BCP, 15,16 and BCPs formed by mesogen-

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Section: Resultsmentioning

confidence: 99%

Hierarchical Nanostructures of Bent-Core Molecules Blended with Poly(styrene-b-4-vinylpyridine) Block Copolymer

et al. 2007

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“…The AZBM‐1 evidences filamentary pattern with banana leaf‐like texture which is highly fluid mesophases with mesophase transition higher than the other monomers22 and indicating that AZBM‐1 was constructed with six‐aromatic ring and other monomers ( AZBM 2 and 3 ) were constructed by five‐aromatic ring. The monomer ( AZBM‐2 ) exhibit SmCP with fluid like mesophase on heating but the filamentary growth pattern with strips and ribbons with fringe pattern (SmCP) was observed during cooling from isotropic23,45 and revealed that AZBM ‐2 is enantiotropic in nature. The AZBM‐2 indicates somewhat lower mesophase transition temperature than AZBM‐3 .…”

Section: Resultsmentioning

confidence: 99%

“…The spontaneous polarization ( P s) of AZBM‐1 and 2 are measured from its switching current of their SmCP phase and found to be 90, 109 nC/cm 2 . It was observed that all the monomers ( AZBM‐1, 2 , and 3 ) are prone to polymerize under the A.C. electric field and, hence, all the data were measured using freshly prepared cells, and the measurement time was limited to be <5 min 23…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, side‐chain bent‐core liquid crystalline polymer predominantly demonstrate rich mesomorphism compare with main‐chain28 as well as side‐chain29 and dendronized liquid crystalline polymers30–36 and which are classified as follows (i) side‐chain bent‐core liquid crystalline polymer (SBCLCPs),15 (ii) bent‐core mesogen‐jacketed liquid crystalline polymers (BMJLCPs),37 (iii) central linked bent‐core liquid crystalline polymer (CBCLCPs),38 and (iv) hydrogen‐bonded side chain bent‐cores liquid crystalline polymers (HBCLCPs)26 were reported based on the polymeric back bone attached with position of bent‐core mesogen pendant. Though BCLCs have been extensively investigated, bent‐core side‐chain polymers were scarcely achieved with barely detectable polar switching properties 23,26…”

Section: Introductionmentioning

confidence: 99%

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Photo and electrically switchable behavior of azobenzene containing pendant bent‐core liquid crystalline polymers

Srinivasan

Kannan

Roy

2012

J. Polym. Sci. A Polym. Chem.

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New class of photo and electrically switchable azobenzene containing pendant bent‐core liquid crystalline monomers (AZBM 1, 2, and 3) and their polymers (AZBP 1, 2, and 3) are reported. The synthesized precursors, monomers, and polymers were characterized by FT‐IR, 1H, and 13C NMR spectroscopy. Thermal stability of polymers was examined by thermogravimetric analysis and revealed stable up to 260 °C. The mesophase transition of monomers and polymers are observed through polarized optical microscopy (POM) and further confirmed by differential scanning calorimetry (DSC). The electrically switching property of monomers and their polymers were studied by electro‐optical method. Among the three monomers AZBM 1, 2, and 3, AZBM 1 and 2 exhibit antiferroelectric (AF) switching and AZBM 3 exhibits ferroelectric (F) switching behavior. On the other hand, low molecular weight polymers (AZMP 1, 2, and 3) show weak AF and F switching behavior. The photo‐switching properties of bent‐core azo polymers are investigated using UV‐vis spectroscopy, trans to cis isomerization occurs around 25 s for AZBP‐1 and 30 s for AZBP‐2 and 3 in chloroform, whereas reverse processes take place around 80 and 90 s. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

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“…Photopolymerization using photopolymerizable groups such as acrylate or methacrylate has been used to lock the FE order and improve the mechanical properties of materials [189][190][191]. Moreover, other macromolecular designs such as polymers [192][193][194][195][196], Langmuir-Blodgett films [197][198][199], or sol-gel materials [200], can also be explored for bent-core NLO applications.…”

Section: Nonlinear Opticsmentioning

confidence: 99%

Electric‐ and Light‐Responsive Bent‐Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications

Zhang¹

2013

Intelligent Stimuli‐Responsive Materials

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The three classic states of matter are well known and ubiquitous in everyday life: solid, liquid, and gas. Liquid crystals (LCs), an intermediate state between solid crystal and isotropic liquid, constitute a new fascinating class of condensed soft matter uniquely combining both fluidity and long-range order. The fluid-like mobility enables LCs to be switchable under external stimuli, and crystal-like long-range order bestows anisotropic physical properties on LCs. LCs can be divided into two main classes: thermotropic and lyotropic. Thermotropic LCs consist of individual molecules (or ion pairs) and exhibit phase transitions with the change of temperature. In this case, temperature is the fundamental thermodynamic factor determining mesophase formation. Lyotropic LCs are a special type of solution system that can form mesophases as a function of both temperature and concentration of LC molecules. The building block of a lyotropic phase is an aggregate (called a micelle) formed via self-assembly of many molecules (typically on the order of 100). Examples of LCs can be found both in the natural world and in technological applications. Thermotropic LCs find 189 190 ELECTRIC-AND LIGHT-RESPONSIVE BENT-CORE LIQUID CRYSTALS a wide variety of uses in displays, and an important example of lyotropic LCs is cell membranes formed by amphiphilic lipids. Surfactants in water (i.e., soap water) constitute another useful example of lyotropic LCs. Although the majority of LCs are organic molecules, there exist many LC materials incorporating metals into organic anisotropic molecules [1-3]. These organic-inorganic hybrid LC materials are described as metallomesogens and are recently called metallotropic LCs [4] as distinguished from two main LC classes. In fact, metallomesogens can be classified as either thermotropic or lyotropic LCs depending on their composition and conditions. However, it should be noted that metallomesogens offer a material platform to incorporate magnetic, electronic, optical, redox, and catalytic properties common to inorganic materials into LCs.Although thermotropic LCs have been known to scientists for over 100 years since a discovery by the Austrian botanical physiologist Friedrich Reintizer in 1888, it was only in the late 1960s that they began to be used in display applications. Today, they are best known for their exceptionally successful commercial applications in flat panel display products such as TVs, smart phones, computer displays, and digital projectors. Although today's LC display technology is becoming very advanced, LC materials used in display devices possess the simplest nematic (N) phase and their molecules have been variants on simple rod shapes (Fig. 6.1a). Besides nematic phases, LCs can exhibit other phases: smectic (Sm), columnar (Col), and cubic phases, depending on the orientational or positional orders of their molecules. Nematic phases have only long-range orientational order, smectic mesophases exhibit one-dimensional (1D) positional order and form two-dimensional (2D) layered ...

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Side-Chain Liquid Crystalline Poly(meth)acrylates with Bent-Core Mesogens

Cited by 38 publications

References 45 publications

Hierarchical Nanostructures of Bent-Core Molecules Blended with Poly(styrene-b-4-vinylpyridine) Block Copolymer

Hierarchical Nanostructures of Bent-Core Molecules Blended with Poly(styrene-b-4-vinylpyridine) Block Copolymer

Photo and electrically switchable behavior of azobenzene containing pendant bent‐core liquid crystalline polymers

Electric‐ and Light‐Responsive Bent‐Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications

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