A SAXS Study of Microstructure Ordering Transitions in Liquid Crystalline Side-Chain Diblock Copolymers

Anthamatten, Mitchell; Hammond, Paula T.

doi:10.1021/ma9910989

Cited by 53 publications

(71 citation statements)

References 40 publications

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“…Anthamatten and co-workers also found that the SCLC block copolymers of polystyrene and methacrylates containing (s)-2-methyl-1-butyl-4 0 -(((4-hydroxyphenyl)carbonyl)oxy)-1,1 0 -biphenyl-4-carboxylate mesogens (PS-b-HBPB) can form hexagonally closepacked PS cylinders at a higher LC volume fraction, while they self-assemble into completely lamellar structures or predominantly lamellar structures at a lower LC volume fraction. 51,52 These experimental observations are in qualitative accordance with the simulated phase transition from C A to L and then to G C with an increasing value of N A .…”

Section: Comparison With Exible Copolymers and Available Experimentasupporting

confidence: 84%

Phase behaviors of side chain liquid crystalline block copolymers

Huang

Jiang

et al. 2015

RSC Adv.

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The microphase separation of side chain liquid crystalline (SCLC) block copolymers was studied using dissipative particle dynamics (DPD) simulations. The block copolymer monomer consists of flexible A segments and flexible B segments grafted by rigid C side chains, where the A, B and C blocks are incompatible with each other. The phase structures of the SCLC copolymers were found to be controlled by A and C block lengths and the graft number. Various mesophases, such as spheres, cylinders, gyroids, and lamellae, were obtained. Phase stability regions in the space of C block length and A block length (or graft number and A block length) were constructed. The packing ordering of C side chains was also studied, and discovered to increase as the temperature decreases or the rigid C side chains increase. In addition, the results of the SCLC copolymers were compared with those of flexible copolymers and available experimental observations. The simulation results in the present work provide useful information for future investigations on SCLC copolymers.

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Section: Comparison With Exible Copolymers and Available Experimentasupporting

confidence: 84%

Phase behaviors of side chain liquid crystalline block copolymers

Huang

Jiang

et al. 2015

RSC Adv.

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“…Similar behavior of enhanced stability of spherical phases has been previously reported with side-chain liquid crystalline diblock copolymers. 40,41 Finally, we would like to point out that the lam-in-HPL structure was repeatedly observed despite careful annealing. At present, we cannot conclusively determine whether it is a very long-lived metastable state or equilibrium structure.…”

Section: Resultsmentioning

confidence: 94%

Self-Assembled Structures in Diblock Copolymers with Hydrogen-Bonded Amphiphilic Plasticizing Compounds

et al. 2006

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Hydrogen-bonding amphiphilic low molecular weight plasticizing compounds to one block of diblock copolymers to form supramolecular comblike blocks leads to hierarchical self-assembly at the block copolymer (long) and amphiphile (short) length scales, in which lamellar-in-lamellar order and the related phase transitions have previously been shown to allow thermal switching of electrical and optical properties [Science 1998, 280, 557; Nat. Mater. 2004, 3, 872]. In this work other hierarchies and phase transitions are systematically searched, a particular interest being hierarchies containing gyroid structures and the related order−order transitions. Polymeric supramolecular comb−coil diblock copolymers consisting of a polystyrene (PS) coillike block and a supramolecular comblike block based on poly(4-vinylpyridine) (P4VP) are used, where the pyridines are either directly hydrogen bonded with 3-pentadecylphenol (PDP), i.e., PS-block-P4VP(PDP)1.0, or first protonated with methanesulfonic acid (MSA) and then hydrogen bonded to PDP, i.e., PS-block-P4VP(MSA)1.0(PDP)1.0. In this way the comblike block can be noncharged or charged. The morphologies were determined using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) at different temperatures. In the case of PS-block-P4VP(PDP)1.0, all classical diblock copolymer morphologies were observed at room temperature, where the P4VP(PDP)1.0 domains contain an additional lamellar structure due to the supramolecular comblike blocks. Here we report novel gyroid and hexagonal perforated layer morphologies, i.e., where the PS and P4VP(PDP)1.0 blocks form gyroid or hexagonal perforated layer order and the P4VP(PDP)1.0 domains have an internal lamellar order. Heating past ca. T = 60 °C causes an order−disorder transition within the P4VP(PDP)1.0 domains. Further heating leads to gradually reduced hydrogen bonding strength, and importantly PDP becomes soluble in PS at T > ca. 120 °C. At such temperatures PDP is found in both the P4VP and PS domains, thus leading to changes in the relative volume fractions of the domains, which in turn leads to order−order transitions. In PS-block-P4VP(MSA)1.0(PDP)1.0, typically lamellar and cylindrical block copolymeric structures were observed, where there was an additional internal lamellar order within the P4VP(MSA)1.0(PDP)1.0 domains. Coincidentally, an order−disorder transition within the P4VP(MSA)1.0(PDP)1.0 domains takes place at T = ca. 125 °C. Above that temperature, PDP is in both PS and P4VP(MSA)1.0 domains, but most interestingly at ca. T > 175 °C PDP becomes a nonsolvent for P4VP(MSA)1.0 and it is therefore expelled to predominantly to the PS domains. This manifests as an order−order transition. All samples exhibit at least two thermoreversible order−order transitions, and some of them show even five consecutive self-assembled phases as a function of temperature. Besides being amphiphilic, PDP can also be regarded as a plasticizer, i.e., relatively nonvolatile solvent, for the P4VP, PS, and P4VP(MSA)1.0 with cha...

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“…4. Recently, some evidence along these lines has emerged [16,17]. Currently, the effect of spacer length on mesogen anchoring is being investigated in hydrogen bonded analogs of these side group LC BCPs by our group [32].…”

Section: Influence Of Boundary Anchoring Conditionsmentioning

confidence: 99%

“…More recently, Hammond and coworkers [16,17] have synthesized a styrene-methyl methacrylate diblock copolymer in which the methyl methacrylate block is functionalized with a chiral mesogen using spacers of 6 and 10 carbon atoms. The mesogen in this case is based on a biphenyl benzoate core.…”

Section: Introductionmentioning

confidence: 99%

Understanding and controlling the morphology of styrene–isoprene side-group liquid crystalline diblock copolymers

Osuji

Chen

Mao

et al. 2000

Polymer

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In side-chain liquid crystalline diblock copolymers, driving forces for ordering of the material may be provided by the chemical incompatibility between the blocks and by the liquid crystalline nature of one of the blocks. We study the microstructure and its development from initially isotropic solutions in side-group liquid crystalline copolymers based on styrene-isoprene diblocks. Hierarchical structure from the 5 Å to the 500 Å length scale is observed, the product of coherent block copolymer microphase separation and liquid crystalline mesophase formation. The presence of cylindrical microdomains of either the poly(isoprene-LC) or poly(styrene) block markedly increased the thermal stability of the LC. Confinement of the LC to cylindrical microdomains strongly inhibited defect formation within the mesophase after suitable orientation and thermal treatment, readily manifested by the significantly improved optical clarity of these samples versus LC matrix or LC lamellar samples. We consider the relative stabilities of parallel-transverse, perpendicular-parallel, parallel-parallel and transverse-perpendicular arrangements of the microdomain and mesophase structures in interpreting the development of structure in these materials under oscillatory shear. ᭧

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A SAXS Study of Microstructure Ordering Transitions in Liquid Crystalline Side-Chain Diblock Copolymers

Cited by 53 publications

References 40 publications

Phase behaviors of side chain liquid crystalline block copolymers

Phase behaviors of side chain liquid crystalline block copolymers

Self-Assembled Structures in Diblock Copolymers with Hydrogen-Bonded Amphiphilic Plasticizing Compounds

Understanding and controlling the morphology of styrene–isoprene side-group liquid crystalline diblock copolymers

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