Adsorption of copolymers aggregates: from kinetics to adsorbed layer structure.
We examined the adsorption, on hydrophobic and hydrophilic surfaces, of 4 rake-type poly(dimethyl siloxane) (PDMS) copolymers varying the amount of poly(ethylene glycol) (PEG) graft arms from 41 to 72%. The copolymers formed large aggregates in solution, complicating their adsorption kinetics and layer structures. We found the adsorption process always to be dominated by the adsorption of large aggregates, with strongly bound layers resistant to rinsing in adsorbing buffer. Adsorbed amounts were nearly independent of the substrate. However, subtleties in the adsorption kinetics suggested different layer structures for the different systems. On hydrophilic silica, aggregates adsorbed at the transport limited rate until surface saturation, and associated interfacial structures were likely retained. On the hydrophobic surface, a subset of the copolymers exhibited retarded late stage adsorption kinetics suggestive of brush formation. This work demonstrates how subtle differences in adsorption kinetics provide insight into potential interfacial layer structures.
Zdyrko
Bogdan
B
Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA.
Ofir
Pazit Bar-Yosef
PB
Alb
Alina M
AM
Reed
Wayne F
WF
Santore
Maria M
MM
D000327:Adsorption; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D007700:Kinetics; D008422:Materials Testing; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D012822:Silicon Dioxide; D013500:Surface Tension
D020099:Coated Materials, Biocompatible; D004129:Dimethylpolysiloxanes; D011108:Polymers; D011092:Polyethylene Glycols; C013830:baysilon; D012822:Silicon Dioxide