Related Experiment Video
Updated: Jul 8, 2026
11:17
Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction
Published on: January 19, 2016
Order and strain in main-chain smectic liquid-crystalline polymers and elastomers
W H de Jeu1, E P Obraztsov, B I Ostrovskii
1FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam, The Netherlands. dejeu@mail.pse.umass.edu
The European Physical Journal. E, Soft Matter
|January 22, 2008
Summary
Main-chain liquid-crystal polymers and elastomers exhibit distinct layer correlations. Defects in main-chain systems directly distort layers, affecting X-ray scattering patterns and revealing domain structures.
Area of Science:
- Materials Science
- Polymer Physics
- Soft Matter Physics
Background:
- Smectic liquid-crystal polymers and elastomers are advanced materials with ordered layered structures.
- Understanding layer correlations is crucial for predicting material properties and performance.
- Main-chain systems differ from side-chain systems in chain orientation relative to the layers.
Purpose of the Study:
- To investigate layer correlations in main-chain smectic liquid-crystal polymer and elastomer systems.
- To elucidate the impact of polymer chain orientation and defects on lamellar structure.
- To compare the structural characteristics of homopolymers and elastomers within these systems.
Main Methods:
- High-resolution X-ray scattering was employed to probe layer correlations.
- Analysis of X-ray lineshapes provided insights into order, domain size, and structural defects.
- Comparison of scattering data between polymer and elastomer systems.
Main Results:
- In main-chain systems, polymer chains align parallel to the layer normal, directly coupling to the lamellar structure.
- Polymer defects in main-chain systems translate into significant layer distortions.
- Homopolymers exhibit Lorentzian X-ray lineshapes, indicating averaged algebraic order in hundreds-of-nm domains.
- Elastomers display broader peaks than polymers, attributed to non-uniform strain from layer structure defects.
Conclusions:
- Layer distortions are a direct consequence of chain orientation and defects in main-chain liquid-crystal polymers.
- X-ray scattering effectively characterizes domain structure and order decay in these materials.
- Elastomeric cross-linking introduces strain, further influencing the observed layer correlations and scattering profiles.
Related Concept Videos
01:21Polymer Classification: Crystallinity
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
01:28Classification and Mechanical Properties of Synthetic Polymers
Synthetic polymers are classified as elastomers, fibers, or plastics based on their crystallinity. Crystallinity, the degree of long-range order in the solid state, influences the mechanical properties (stretching or contracting) of elastomers. Elastomers are flexible polymers that can expand or contract easily upon the application of an external force. They have numerous crosslinks that pull them back into their original shape when stress is removed. Silicones, for instance, are highly elastic...
01:14Polymer Classification: Architecture
Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...
01:26Polymer Classification: Stereospecificity
Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...
02:29Conformations of Cycloalkanes
Adolf von Baeyer attempted to explain the instabilities of small and large cycloalkane rings using the concept of angle strain — the strain caused by the deviation of bond angles from the ideal 109.5° tetrahedral value for sp3 hybridized carbons. However, while cyclopropane and cyclobutane are strained, as expected from their highly compressed bond angles, cyclopentane is more strained than predicted, and cyclohexane is virtually strain-free. Hence, Baeyer’s theory that was based on the...
01:24Determination of Molar Masses of Polymers I
Polymerization produces macromolecules with a range of chain lengths due to the random nature of molecular growth processes. As chains form and terminate at different stages, a single polymer sample contains molecules of varying sizes rather than a uniform structure. This variability is described using average molar masses and distribution-related parameters, which together provide a comprehensive understanding of polymer characteristics.The distribution of molar masses plays a critical role in...