Compact polyelectrolyte complexes: "saloplastic" candidates for biomaterials.
Precipitates of polyelectrolyte complexes were transformed into rugged shapes suitable for bioimplants by ultracentrifugation in the presence of high salt concentration. Salt ions dope the complex, creating a softer material with viscous fluid-like properties. Complexes that were compacted under the centrifugal field (CoPECs) were made from poly(diallyldimethyl ammonium), PDADMA, as polycation, and poly(styrene sulfonate), PSS, or poly(methacrylic acid), PMAA, as polyanion. Dynamic mechanical testing revealed a rubbery plateau at lower frequencies for PSS/PDADMA with moduli that decreased with increasing salt concentration, as internal ion pair cross-links were broken. CoPECs had significantly lower modulii compared to similar polyelectrolyte complexes prepared by the "multilayering" method. The difference in mechanical properties was ascribed to higher water content (located in micropores) for the former and, more importantly, to their nonstoichiometric polymer composition. The modulus of PMAA/PDADMA CoPECs, under physiological conditions, demonstrated dynamic mechanical properties that were close to those of the nucleus pulposus in an intervertebral disk.
Porcel
Claudine H
CH
Department of Chemistry and Biochemistry, The Florida State University, Tallahassee, Florida 32306, USA.
Schlenoff
Joseph B
JB
D001672:Biocompatible Materials / Q000737:chemistry*; D019245:Compressive Strength; D004573:Electrolytes / Q000737:chemistry*; D010969:Plastics / Q000737:chemistry*; D011095:Polyethylenes / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry
D001672:Biocompatible Materials; D004573:Electrolytes; D010969:Plastics; D011095:Polyethylenes; D011108:Polymers; D000644:Quaternary Ammonium Compounds; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; D012965:Sodium Chloride