The bond(Si-O-B) is dynamic and reversible.
Please note that the key ingredient of Kinetic Sand would be polyborodimethylsiloxane (PBDMS) or polyborosiloxane (PBS) derived by a crosslinking reaction between organic boron compounds and polydimethylsiloxane (PDMS). The so-called "grab-release" mechanism of such "reversible bonds" (Si-O-B) results in the self-healing, energy absorbing, viscoelastic flow properties of silly putties and the likes. The original "Silly Putty" is based on the accidental finding by James Wright, an R&D chemical engineer, at GE in 1943! It is now commercially available from Dow Corning, Wacker, Shin-Etsu, Silikony Polskie, etc.
"Since boric acid is trifunctional, a single boron has the ability to join three polysiloxane chains together. This joining of chains is called cross-linking. Cross-linking produces a high molecular weight polymer that is a soft, pliable gum with very interesting chemical properties." (https://www.wou.edu/las/physci/ch462/BouncingPutty.htm
Dr Phil Green at the University of Hertfordshire in Hatfield, now technical director of d3o Lab describes d3o foam material as, "An elastic cellular polymer containing transient dynamic cross links. (http://www.eurekamagazine.co.uk/design-engineering-features/technology/cross-links-cushion-impacts/2894/
His further comments are:
"The material can be moulded into virtually any shape, which has enabled us to optimise the geometry for maximum conformity, flexibility and breathability for integration into garments. It can be either fabric backed for easy integration into clothing or moulded into discrete components. We currently supply a polo company, Casablanca, with moulded inserts for their polo knee protectors.
"We have a number of automotive applications we want to explore, such as suspension bushes, pillar liners and sound insulation. Although the cost is not prohibitive and will come down with volume production it is a premium material that is high value add and not a commodity sheet material, although we are looking at continuous sheet production for the near future. The raw materials are not commercially available and have been formulated to our specification.