Inducing and Measuring Bridging in Telechelic Polymer Brushes

• Published in: Macromolecules Vol. 29; no. 12; pp. 4412 - 4416
• Main Authors: Tang, Wilfred H, Witten, Thomas A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 03.06.1996
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Surface properties; Interface structure; Solid liquid solid interaction; Liquid solid interface; SCF method; Planar interface; Telechelic polymer; Theoretical study; Modeling; Parallel plate
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma951547e

We investigate bridging in a telechelic polymer brush in solution using the Milner−Witten−Cates self-consistent mean-field model. For an uncompressed brush between flat, parallel plates, the equilibrium number of bridges is predicted to be proportional to (R/L 0)2, where R is the root-mean-square end-to-end distance and L 0 is the equilibrium brush height. Upon compressing this system, a much higher number of bridges form. For moderate compression L 0 − L such that ξ ≪ L 0 − L ≲ L 0/2, where ξ is the interpenetration depth between two opposing brushes, the number of bridges is proportional to (L 0 − L)(R/L 0)2/3. Changing the geometry of the system from flat, parallel plates to crossed cylinders changes the way the number of bridges scales with compression distance. In the crossed cylinder configuration, under moderate compression M such that ξ ≪ M ≲ L 0/2, the number of bridges is proportional to M 2(R/L 0)2/3. If the two surfaces are pulled apart with a fixed number of bridges, the tensile force is approximately proportional to the number of bridges, for both the parallel plate configuration and the crossed cylinder configuration.