Heteromeric liquid-crystalline association chain polymers: structure and properties

Lee, C.-M.; Jariwala, C.; Griffin, Anselm C.

doi:10.1016/0032-3861(94)90801-x

Cited by 83 publications

(43 citation statements)

References 13 publications

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“…3,4 Both low molecular weight and polymeric liquid crystals have been realized using hydrogen bonding, starting with the pioneering work of Kato and Frechet 5 and continued by others in different systems. [6][7][8][9][10][11][12][13][14][15] Ruokolainen et al have used hydrogen bonding and charge transfer to complex aliphatic chains to homopolymers [16][17][18][19][20][21][22][23] and block copolymers. 24 Hydrogen bonding has also been used as a facile method for the preparation of LC block copolymers with novel thermooptic properties 25 and that exhibit orientational switching of the microstructure under electric fields.…”

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confidence: 99%

Supramolecular Microphase Separation in a Hydrogen-Bonded Liquid Crystalline Comb Copolymer in the Melt State

2006

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Hydrogen bonding represents a versatile and convenient route to chemical diversity in natural and synthetic systems. It can be used to join various chemical species to one another to form products ranging from simple dimers to complex supramolecular moieties, some of which may be self-ordering. 1,2 The use of hydrogen bonding to create liquid crystalline materials is an example of using molecular recognition to pursue prescribed molecular or supramolecular architectures for use in functional systems with self-assembled structures. 3,4 Both low molecular weight and polymeric liquid crystals have been realized using hydrogen bonding, starting with the pioneering work of Kato and Frechet 5 and continued by others in different systems. [6][7][8][9][10][11][12][13][14][15] Ruokolainen et al. have used hydrogen bonding and charge transfer to complex aliphatic chains to homopolymers [16][17][18][19][20][21][22][23] and block copolymers. 24 Hydrogen bonding has also been used as a facile method for the preparation of LC block copolymers with novel thermooptic properties 25 and that exhibit orientational switching of the microstructure under electric fields. 26 The current work represents another instance of supramolecular engineering via hydrogen bonding.Poly(acrylic acid) of molecular weight 5.2 kg/mol and polydispersity 1.09 was used as received from Polymer Source. The custom-synthesized mesogen was based on an imidazole headgroup and a rigid biphenyl core, with 10-and 8-carbon aliphatic spacer and tail segments, respectively, as shown in Figure 1.Samples were prepared by codissolving appropriate quantities of PAA and the mesogen in DMF at 2.5 wt % followed by slow solvent removal at 55°C to prevent mesogen crystallization and phase separation. The films produced were dried in a vacuum at room temperature for 72-96 h and used without further treatment. SAXS was performed using a rotating copper anode source (λ ) 1.540 Å) and, primarily, a synchrotron source (λ ) 1.307 Å). DSC was conducted on a Perkin-Elmer DSC7 at a heating rate of 10°C/min. FTIR was performed in reflection on films using a microscope objective for both illumination and collection of reflected radiation on a Nicolet instrument.The mesogen forms a room temperature crystalline solid in the unbound state, with a single, sharp melting transition to a disordered liquid at 97°C. X-ray scattering revealed a layered structure of 35 Å period in the small-angle regime and characteristic peaks on the 3-5 Å range in the wide-angle regime. The layer period was in good agreement with the calculated extended chain length of the molecule, 34 Å.The presence of hydrogen bonding between the imidazole head of the mesogen and the hydroxy group of the acrylic acid repeat units was confirmed by FTIRsthe appearance of a new, broad band centered on 2530 cm -1 was the primary indicator of strong imidazole-carboxylic acid hydrogen bonding. 15 The intensity of the band was found to decrease as samples were heated above room temperature, with recovery of the room temperature ab...

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Supramolecular Microphase Separation in a Hydrogen-Bonded Liquid Crystalline Comb Copolymer in the Melt State

2006

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“…Kato et al (1995) juga melakukan sintesis liquid crystalline polimer dari reaksi antara asam benzoate dan 2-aminopyridines melalui satu atau dua ikatan hidrogen. Sedangkan Lee et al (1994) menggunakan dipyridine dan asam dikarboksilat untuk membuat liquid crystalline polimer.…”

Section: Supramolekular Polimerunclassified

Kajian Tentang Self-Healing Rubber Self Healing Rubber Review

Purbaya¹

2015

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Abstrak B a r a n g j a d i k a r e t s e l a m a m a s a pemakaiannya dapat mengalami cracking. Untuk mengatasi masalah ini maka konsep selfhealing dapat digunakan. Self-healing merupakan kemampuan dari suatu material untuk dapat memperbaiki dirinya sendiri setelah mengalami kerusakan. Konsep ini dapat digunakan untuk menambah umur pemakaian suatu produk. Strategi yang dapat digunakan dalam pembuatan material selfhealing adalah : 1) pembentukan ikatan silang pada polimer, 2) pelepasan healing agent pada s a a t m e m p r o d u k s i p o l i m e r, d a n 3 ) menggunakan teknologi khusus seperti konduktiviti, electro-fluid-dynamic (EFD), migrasi nano partikel, efek shape memori dan co-deposition. Salah satu supramolekular polimer yang memiliki sifat elastis dan healing ability adalah self-healing rubber. Self-healing rubber disintesis melalui dua tahap sintesis, yaitu 1) pembuatan oligoamide, dan 2) mereaksikan oligoamide yang diperoleh dari tahap pertama reaksi dengan urea untuk menghasilkan self-healing rubber. Karet yang diperoleh memiliki sifat elastis dan sifat healing ability setelah mengalami kerusakan. Sifat ini tidak ditemukan dalam karet alam maupun karet sintesis. Jenis karet baru ini sangat menarik untuk dipelajari dan diaplikasikan untuk teknologi karet.

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“…The optical texture exhibited by such a solution when viewed through a polarizing optical microscope (POM) suggests that the phase is nematic. Griffin and coworkers [41][42][43][44][45][46][47] studied the thermotropic LC properties of chain-extended supramolecular polymers of various structurally different bispyridyls as H-bond acceptors with [(oxydiethoxyethylene)dioxy]-bis(4-benzoic acid) [also known as tetraethyleneglycoxybis(4-benzoic acid)] as an H-bond donor. The bispyridyls used are trans-1,2-bis(4-pyridyl)ethylene, 4,49-(1,10-decanedioxy)diphenolbis(4-pyridinecarboxylate) and hydroquinonebis(4-pyridinecarboxylate).…”

Section: Introductionmentioning

confidence: 99%

Main chain, thermotropic, liquid crystalline, hydrogen‐bonded polymers of 4,4′‐bipyridyl with 4,4′‐dicarboxy‐α,ω‐diphenoxyalkanes

Bhowmik

Wang²,

Han

2007

Liquid Crystals

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A series of main chain, thermotropic, liquid crystalline (LC) hydrogen-bonded polymers based on 4,49-bipyridyl as a hydrogen bond acceptor and 4,49-dicarboxy-a,v-diphenoxyalkanes as hydrogen bond donors were prepared by a slow evaporation technique from a pyridine solution and characterized for their thermotropic LC properties using a variety of experimental techniques. The homopolymer of 4,49-bipyridyl with 4,49-dicarboxy-1,9-diphenoxynonane exhibited relatively low T m at 205uC and low T i at 230uC, giving an LC phase range of 25uC. The other two homopolymers with 4,49-dicarboxy-1,6-diphenoxyhexane and 4,49-dicarboxy-1,9-diphenoxydecane exhibited relative low T m values, above which each of them formed highorder smectic phases. With further heating at higher temperature they transformed into loworder smectic phases that persisted up to their decomposition temperatures. Several copolymers also had relatively low T m values as well as low T i values and, therefore, had a broad LC phase range (22-77uC). All of the polymers including copolymers exhibited highorder and low-order smectic phases, since they developed usually mosaic and schlieren (or bâ tonnets) textures. Generally, copolymerization increased the temperature range of the LC phases for these polymers. The thermal transitions of all of the polymers were well below their decomposition temperatures, which were in the ranges of 254-329uC.

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Heteromeric liquid-crystalline association chain polymers: structure and properties

Cited by 83 publications

References 13 publications

Supramolecular Microphase Separation in a Hydrogen-Bonded Liquid Crystalline Comb Copolymer in the Melt State

Supramolecular Microphase Separation in a Hydrogen-Bonded Liquid Crystalline Comb Copolymer in the Melt State

Kajian Tentang Self-Healing Rubber Self Healing Rubber Review

Main chain, thermotropic, liquid crystalline, hydrogen‐bonded polymers of 4,4′‐bipyridyl with 4,4′‐dicarboxy‐α,ω‐diphenoxyalkanes

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