Interaction between Finite-Sized Particles and End Grafted Polymers
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- 作者：G. Subramanian ; D. R. M. Williams ; and P. A. Pincus
- 刊名：Macromolecules
- 出版年：1996
- 出版时间：May 20, 1996
- 年：1996
- 卷：29
- 期：11
- 页码：4045 - 4050
- 全文大小：160K
- 年卷期：v.29,no.11(May 20, 1996)
- ISSN：1520-5835
文摘
We describe the deformation behavior of polymer brushesand mushrooms compressed byfinite-sized particles for the cases where the chains are fixed ormobile on the grafting surface. Whenthe size of the particle is large compared to the grafting distance ofthe chains, the force on the particleis the same to lowest order in compression for both the fixed andsurface mobile chains. Compression ofa single mushroom can lead to a first order like escape transition,where part of the chain escapes fromunder the particle. These transitions can be seen either in thechain radius or in the compressionalforce law behavior. For surface mobile mushrooms, the force isconsiderably smaller because of theevacuation of chains from under the particle. The force law inthis case also exhibits a maximum at acertain compression, indicating that the system undergoes a collapsetransition above a critical pressureor yield stress Pc 
kT
0RF3-1,where 0 is the grafting density (chains/area) andRF3 is the unperturbedmushroom size. Finally, we consider the case of bending of stiffchains grafted to a solid surface. In thecase of a single chain, the force is a constant for weak compressions.In the multichain case, the forcecan be substantially lower because of the escape of chains from underthe particle.
kT0RF3-1,where 0 is the grafting density (chains/area) andRF3 is the unperturbedmushroom size. Finally, we consider the case of bending of stiffchains grafted to a solid surface. In thecase of a single chain, the force is a constant for weak compressions.In the multichain case, the forcecan be substantially lower because of the escape of chains from underthe particle.