Aqueous Amino Silane Modification of E-glass Surfaces

The Effect of Solvent and Fiber Treatment on the Deposition of Organic Silane Solutions Using THF and Acetone

“…The stoichiometric balance point for a ureido silane was measured as 6.8 (9). As the outer layers of silane were removed by washing, the isoelectric point (iep), that point at which the surface charge was neutral, was reduced and an Si-O-Si surface was revealed.…”

“…The ureido silane examined here has primary and secondary amino groups and a carboxy functional group and as such should, in theory, be compatible with many of the polymer systems for which amino silanes are currently in use. Previous work, however, has shown that ureido silanes have the tendency to deposit "upside down" from aqueous systems and from a range of organic solvent systems (7)(8)(9). It has recently been shown that chemisorbed ureidosilane was bonded to the surface at relatively few points with Si-O-Si bonds (10).…”

“…It has recently been shown that chemisorbed ureidosilane was bonded to the surface at relatively few points with Si-O-Si bonds (10). The silane formed a highly cross-linked upper layer or skin, on top of the deposited patches of silane, giving the appearance of a fully coated fiber (9,11). A combination of ζ -potential and dynamic contact angle results confirmed the patchy nature of a surface deposited from low-concentration silane solutions (0.005 wt%).…”

“…Higher concentration silane solutions (0.15 wt%) gave the appearance of being fully coated, while still releasing ions into solution from the incompletely covered surface. The porous structure produced would be a repository for solvent, water, and unreacted silane (9,11). Some of the outer layers could be removed or reoriented by judicious application of washing solvents (7,12,13).…”

Silane Coupling Agents

“…A comparison of critical surface tensions for some polymers and coupling agent films (1,27) shows that the functional groups can vary the surface tension from very low (similar to polytetrafluoroethylene) to rather high (close to glass) (27). Indeed, the variation of surface energies and zeta potential with different treatments of the same coupling agent can even be large (28). The use of an appropriate coupling agent should allow the modification of a surface so that an organic polymer will wet it.…”