Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Isotropic-----------------------------------block copolymers material

The homopolymer showed an enantiotropic nematic mesophase, whereas the diblock copolymer generated microphase-separated lamellae, in which the SCLCP block possessed a nematic-isotropization transition similar to the homopolymer (Table 17). Upon heating, the nematic microphase decreased continuously in the nematic phase from 38.5 nm to 27 nm and showed a constant value of about 26 nm after the nematic-isotropization transition. Therefore, materials in which these block copolymers are macroscopically aligned are expected to show reversible contraction in one dimension, making this polymer system an interesting candidates for an artificial muscle or actuator. [Pg.76]

Liquid crystals combine properties of both liquids (fluidity) and crystals (long range order in one, two, or three dimensions). Examples of liquid crystalline templates formed by amphiphiles are lyotropic mesophases, block copolymer mesophases, and polyelectrolyte-suxfactant complexes. Their morphological complexity enables the template synthesis of particles as well as of bulk materials with isotropic or anisotropic morphologies, depending on whether the polymerization is performed in a continuous or a discontinuous phase. As the templating of thermotropic liquid crystals is already described in other reviews [47] the focus here is the template synthesis of organic materials in lyotropic mesophases. [Pg.213]

Rimplast materials from Petrarch are silicone/thermoplastic IPNs that combine the warpage and wear resistance properties of silicone with nylon, thermoplastic polyurethane, or styrene/butadiene block copolymers. The combination of properties these IPNs possess make them suitable for high quality, high tolerance gear and bearing applications that can benefit from the addition of internal lubrication and isotropic shrinkage of silicone to the fatigue endurance and chemical resistance of crystalline resin, while processability still remains the same. [Pg.539]

Phase transitions in condensed phases are characterized by symmetry changes, i.e. by transformations in orientational and translational ordering in the system. Many soft materials form a disordered (isotropic) phase at high temperatures but adopt ordered structures, with different degrees of translational and orientational order, at low temperatures. The transition from the isotropic phase to ordered phase is said to be a symmetry breaking transition, because the symmetry of the isotropic phase (with full rotational and translational symmetry) is broken at low temperatures. Examples of symmetry breaking transitions include the isotropic-nematic phase transition in hquid crystals (Section 5.5.2) and the isotropic-lamellar phase transition observed for amphiphiles (Section 4.10.2) or block copolymers (Section 2.11). [Pg.18]

The main state-of-the-art of presented work is based on development of new strategy of preparation of thermo-responsive materials in which, amphiphilic block copolymers are used as both a nanostructured agent for epoxy network and as a dispersing agent for low molecular liquid crystals. These novel materials can find application in the field of liquid crystals which possess nematic-isotropic transition and allow the designing of materials which can switch from the opaque... [Pg.157]


See other pages where Isotropic-----------------------------------block copolymers material is mentioned: [Pg.135]    [Pg.610]    [Pg.136]    [Pg.137]    [Pg.704]    [Pg.6]    [Pg.243]    [Pg.525]    [Pg.68]    [Pg.106]    [Pg.131]    [Pg.402]    [Pg.198]    [Pg.178]    [Pg.429]    [Pg.72]    [Pg.341]    [Pg.22]    [Pg.3544]    [Pg.92]    [Pg.359]   
See also in sourсe #XX -- [ Pg.28 ]




SEARCH



Copolymers materials

Isotropic material

Material blocking

Materials block copolymers

© 2024 chempedia.info