PAMPS gels, frictional force

Figure 24a, b show the frictional forces (F) and frictional coefficient (jU ) of the three kinds of gels as a function of normal pressure (P) [61], The gels were slid on the glass plate in water. The results clearly shows that the frictional coefficient decreases in the order DN > TN > DN-L, indicating that introduction of PAMPS, especial linear PAMPS, as the third network component obviously reduces the frictional coefficient of the gels. 

However, when the PAMPS network is introduced to the DN gel as the third component, frictional coefficient of the TN decreases to --10 which is two orders of magnitude lower than that of the DN gel. This is because the surface of the TN gel is dominated by PAMPS, resulting in repulsive interaction with the glass substrate and reduction of tire frictional force. Furthermore, when linear PAMPS chains are Introduced to tlie surface of the DN gel, the frictional coefficient is significantly reduced to 10 , which is one to three orders of magnitude less than tliat of TN and DN gels, respectively. This demonstrates that tlie linear PAMPS chains on the gel surface reduce frictional force due to further repulsive interaction witli the glass substrate [48, 52, 53],... 

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