Several polymers are made with the repeat units shown above. Rank the polymers i

Question

Several polymers are made with the repeat units shown above. Rank the polymers in order of increasing hydrophilicity: Which of the polymers can be used to make a non-resorbable hydrogel human body? You can pick more than one. Which of the polymers breakdown by hydrolysis? You can pick more than one. Which of the polymers would be best for making storage vessels (beakers, jars, ...etc)? Pick one. Which of them can be used (and how) to make a polymer with a controllable breakdown rate in aqueous solutions?

Explanation / Answer

ANS:

a) Polymers in the order of increasing hydrophilicity:

Basically, hydrophilic polymers are those which contain polar or charged functional groups like -OH, -NH2, -CN, -C=O-, -C(OH)-O, etc. These functional groups helps them to dissolve in water thereby increasing their solubility in water.

Thus More the no. of polar groups, greater the hydrophilicity. If any polymer has same no. of polar groups, steric hinderance is noted down for them to further compare their hydrophilicity. Steric hinderance decreases the hydrophilicity.

Thus, Increasing order is :

V < IV < II < I < VI <III

B) Polymers used to make non- resorbable hydrogels in the human body:

Non resrbable hydrogels have the polymers which have hydrophilic structure which allows them capable of holding large amounts of water in their 3D networks. So the polymers having higher water absorption capacity are best for the synthesis of hydrogels.

Thus, from the above polymers, III is most suitable to make non resorbable hydrogels, but I, II and VI can also be used as they are also hydrophilic in nature.

C) Polymers which breakdown by hydrolysis:

Generally polymers on hydrolysis breakdown to give back their monomers. so polymers having polar groups will be easily broken down into their monomers by hydrolysis while hydrophobic polymers will not be easily broken down.

so. all the above polymers except V can easily breakdown into their respective polymers by hydrolysis.

d) Polymer which is best for making storage vessels:

V type of polymer i.e. polypropylene polymers is best suited for making storage vessels as its homogeniety protects the vessels against chemical attack. They are also durable and cost effective.

Structure no. of polar groups active for bonding with water whether steric hinderance is present or not I 1 No steric hinderance to polar group II 1 weak hinderance due to methyl group III 3 (most hydrophilic) No IV 1 steric hinderance due to phenyl ring V 0 (least hydrophilic) No VI 2 No

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