3. How would the gel absorbency properties differ, and explain why they would di

Question

3. How would the gel absorbency properties differ, and explain why they would differ, if you had used:

No MBA in the reaction?

A lot more MBA?

A lot more VA-044?

Question is from Organic Chemistry Lab on synthesis of a superabsorbent polymer. Polymer was created from Acrylic acid under free-radical conditions. VA-044 is the initiator.

N,N’-methylenebisacrylamide (MBA) was used as a crosslinking agent.

Believe no MBA would mean no crosslinks and polymer would be water-soluble unsure what it would do to absorption. More MBA more crosslinks more ridgid and less absorbent possibly? Not sure.

More VA-044 more chains and consequently shorter chains, unsure how this would affect absorption.

Explanation / Answer

3. Gel properties varies widely with the amount of crosslinking present in its structure. The gel permeability decreases as lesser number of free pores/spaces are available for absorption when highly crosslinked. Therefore,

With No MBA : gel permeability is higher

A lot more MBA : increases crosslinking and thus permeability of the gel goes down.

A lot more VA-044 : ensures shorter polymeric chains. Therefore, permeability of the system increases due to greater surface area available for absorption.

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