"Immiscible Polymer Blend Compatibilization through Pendant Ionic Interactions in Semi-Crystalline Polymer Systems"

H. K. Beecha,b, K. M. Karnaukhc, and J. Edmunda,b, J. Read de Alainzc, C. J. Hawkera,c, and R. A. Segalmanb  

aDepartment of Materials, University of California, Santa Barbara
bDepartment of Chemical Engineering, University of California, Santa Barbara
cDepartment of Chemistry and Biochemistry, University of California, Santa Barbara

.
.

Polymer recycling is an important avenue to reduce commodity plastic waste, but various challenges result in less than 10% of plastics actually being recycled in the U.S.1 One issue that limits mechanical recycling is the immiscibility between dissimilar polymers that results in macrophase separation and poor material properties, necessitating sorting of different polymeric materials.  Prior theoretical work has suggested that small numbers of ionic interactions can be used for immiscible polymer blend compatibilization.2 Recent work has demonstrated that low levels of incorporation of ionic bonds formed via an acid-base proton transfer mechanism results in the formation of optically clear blends in an otherwise incompatible poly(dimethylsiloxane) and poly(n-butyl acrylate) mixture. Unlike this model elastomeric system, hydrocarbon polymers that dominate industry (polyethylene and polypropylene) are semi-crystalline, introducing additional processing considerations.  To this end, the model system is extended to study amorphous (polystyrene) and semi-crystalline (polyethylene) high-Tg polymers containing low levels of ionic bond incorporation. Blends of ionically compatibilized high- and low-Tg polymers result in flexible films. These films are characterized with differential scanning calorimetry, dynamic mechanical analysis, and small angle X-ray scattering, highlighting the underlying rich physics of immiscible polymer blends with sparse incorporation of charged groups..

This work is supported by the National Science Foundation through the Materials Research Science and Engineering Center (MRSEC) at UC Santa Barbara: NSF DMR-2308708 (IRG-1).

References:

(1)        Geyer, R.; Jambeck, J. R.; Law, K. L. Production, Use, and Fate of All Plastics Ever Made. Sci. Adv. 2017, 3 (7), e1700782. https://doi.org/10.1126/sciadv.1700782.

(2)       Fredrickson, G. H.; Xie, S.; Edmund, J.; Le, M. L.; Sun, D.; Grzetic, D. J.; Vigil, D. L.; Delaney, K. T.; Chabinyc, M. L.; Segalman, R. A. Ionic Compatibilization of Polymers. ACS Polym. Au 2022, 2, 299–312. https://doi.org/10.1021/acspolymersau.2c00026.