Shrinkage pore sizes

Long-term cycling Resistance, shrinkage, pore size High resistance, high shrinkage, and very small pore size can lead to poor cycling performance... 

The approach by Brennan with collaborators led to notable improvement in the biocompatibility of sol-gel processing. However, there are some disadvantages. Their approach does not exclude the hydrolytic separation of alcohol. Its presence is detrimental for sensitive biopolymers. Furthermore, the two-stage synthesis is accompanied by the significant shrinkage of sol-gel derived nanocomposites. This leads to a decrease in the pore size that sometimes can restrict the accessibility of enzymes to substrates. 

This shrinkage mechanism occurs only in pores within a fixed range of sizes. In pores larger than 50 nm the tensile force in the water is too small to cause appreciable shrinkage and in pores smaller than 2.5 nm a meniscus cannot form [122]. The amount of cement-paste shrinkage caused by surface tension depends primarily on the water-cement ratio, but it is also affected by cement type and fineness and by other ingredients (such as admixtures, and supplementary cementing materials) which affect pore size distribution... 

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