Cross-linked polymer.?

I'd done this experiment which purposed to cross-linked a linear polymer and to observe changes in physical properties of produced gel as a result of the cross-linking.





In this experiment, the polyvinyl alcohol (PVA) is cross-linked by a hydrated borax molecule.





For information,there are six reaction take place.


1- (PVA with Mn=70000, Concentration=5%, V=10 ml) mix with (Borax, Concentration 5%, V=1.0ml).





2- (PVA with Mn=70000, Concentration=5%, V=10 ml) mix with (Borax, Concentration 10%, V=1.0ml).





3. (PVA with Mn=70000, Concentration=10%, V=10 ml) mix with (Borax, Concentration 5%, V=1.0ml).





4. (PVA with Mn=31000, Concentration=5%, V=10 ml) mix with (Borax, Concentration 5%, V=1.0ml).





5. (PVA with Mn=31000, Concentration=5%, V=10 ml) mix with (Borax, Concentration 10%, V=1.0ml).





6. (PVA with Mn=70000, Concentration=5%, V=10 ml) mix with (Borax, Concentration 10%, V=1.0ml).





Gel is produced.


How is the structure of the gel? Plz someone help me.

Cross-linked polymer.?
Polyvinyl alcohol is a polymer made from vinyl alcohol as you are aware. The actual structure is shown on the website I have provided for you below.





When many vinyl alcohol monomers are linked together a long polymer molecule (PVA) is formed.





The PVA molecule consists of a long chain of carbon atoms (about 4400 carbon atoms per molecule) to which are attached hydrogen atoms and OH groups.





The addition of borate ion, to an aqueous solution of PVA causes dramatic changes in the properties of the solution which can be attributed to the formation of bonds (or crosslinks) between the individual polyvinyl alcohol chains by the borate ion.





The structure of the resulting crosslinked PVA is shown at the weblink provided for you below. The effect of this crosslinking is to produce a three-dimensional network of polyvinyl alcohol chains. This network (you can visualize it as a fish net) traps and immobilizes water molecules, and the resulting product is a "gel". Other examples of gels are fruit jellies, gelatin and "Jello." The properties of the gel will depend upon the amount of crosslinking.

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