Abstract
Polymers are often blended with additives (e.g., polymers, clays) to produce composite materials having desirable physical properties that reflect synergy between the blend constituents. Though polymer blends with small-molecule nematic liquid crystal phases have been investigated (primarily for displays), related materials containing small-molecule smectic phases have not been reported. Guanidinium alkylbenzenesulfonates (GCnBS, where n is the number of carbons in the alkyl chain), which form stable smectic phases at elevated temperatures because of a robust two-dimensional hydrogen-bonding network of guanidinium ions and sulfonate moieties, were melt-blended with various polymers. Rheological characterization of the blends reveals a yielding behavior, characteristic of the pure GCnBS smectic phases, which becomes more pronounced with increasing GCnBS concentration. Two microstructuresone a continuous polymer phase embedded with GCnBS droplets and the other a continuous GCnBS phase with a discontinuous polymer phaseare observed, the latter at GCnBS concentrations as low as 2 wt %. The tendency of the blends to form a microstructure in which GCnBS is continuous requires the existence of a smectic phase (observed only for n ≥ 7) and is dependent on alkyl chain length and GCnBS concentration. Injection of molten blends containing smectic phases into a rectangular mold resulted in stratification of the rectangular composite plaque due to the formation of large two-dimensional crystalline lamellae upon cooling of the GCnBS smectic phase dispersed in the blend. This stratification, which can be attributed to large extensional stresses experienced by the blend during molding, depends on alkyl chain length, GCnBS concentration, and the magnitude of the stresses exerted on the molten blend. These results illustrate that smectic phases can promote unusual microstructures in polymer blends at very low concentrations, which may be useful in certain commercial applications.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
