Chapter 8 Final

Question 1

What are some advanced applications of polymers beyond commodity products?

Answer 1

• Membranes (air/water purification, fuel cells),
• Medicine (drug delivery, artificial organs),
• Semiconductor industries (electrically conductive polymers),
• Defense industries (unusual optical properties),
• Automotive & aerospace (lightweight materials for batteries).

Question 2

What is the role of polymers in membrane science and technology?

Answer 2

• Separation of gases and liquids,
• Proton transport in fuel cells,
• Food packaging (barrier against moisture and oxygen)

Question 3

What is permeability in polymers, and why is it important?

Answer 3

Permeability is the amount of gas or liquid that passes through a polymer film per unit thickness, area, time, and pressure difference. It is important for applications like food packaging, where barrier properties are needed to protect against moisture and oxygen.

Question 4

What are the key properties required for polymers used in medical applications?

Answer 4

Polymers for medical applications must possess:
- Biocompatibility,
- Selective permeability,
- Ability to degrade,
- High strength or modulus.

Question 5

What are some examples of polymers used in medical applications?

Answer 5

• PVC (polyvinyl chloride),
• PP (polypropylene),
• Acrylics,
• PS (polystyrene).

Question 6

What is the role of polymers in kidney dialysis?

Answer 6

Polymers are used in kidney dialysis membranes to remove low to moderate molecular weight compounds (e.g., NaCl, urea) from the blood while retaining larger molecules like plasma proteins. A common polymer used is cellophane (regenerated cellulose).

Question 7

What are the challenges associated with polymer membranes in kidney dialysis?

Answer 7

• Concentration polarization,
• Clogged pores due to the adsorption of plasma proteins.

Question 8

What is controlled drug delivery, and why is it important?

Answer 8

Controlled drug delivery maintains a constant therapeutic concentration of a drug within the body. It is important because:
- Below the therapeutic range, the drug is ineffective.
- Above the therapeutic range, the drug can be toxic.

Question 9

What are the two main types of controlled drug delivery systems?

Answer 9

1. Controlled release: Maintains steady drug concentration over time.
2. Site-directed delivery: Targets specific areas of the body (e.g., tumors, infected tissues).

Question 10

What are some examples of controlled drug delivery systems?

Answer 10

• Micro-/nano-capsules,
• Micro-/nano-spheres,
• Polymer-drug conjugates,
• Micelles,
• Liposomes,
• Hydrogels.

Question 11

What is a reservoir-type drug delivery system?

Answer 11

In a reservoir-type system, the drug is encapsulated by a polymeric membrane (microporous or nonporous). The drug is released at a constant rate if the drug core is maintained at a saturated level.

Question 12

What is a matrix-type drug delivery system?

Answer 12

In a matrix-type system, the drug is dissolved or dispersed within a polymer. The release rate decreases over time as the drug concentration at the surface depletes.

Question 13

What is a polymer-degraded release system, and what polymer is commonly used?

Answer 13

In a polymer-degraded release system, the drug is dispersed in a biodegradable polymer that degrades in the body (via hydrolysis or enzymatic attack). A common polymer used is poly(lactide-co-glycolide).

Question 14

What is a hydrogel, and how is it used in drug delivery?

Answer 14

A hydrogel is a water-swollen polymer network. It is used in drug delivery because it can swell in an aqueous environment, releasing the drug as it expands. A common polymer for hydrogels is poly(2-hydroxyethyl methacrylate) (PHEMA).

Question 15

What are the advantages of site-directed drug delivery?

Answer 15

Site-directed drug delivery:
- Targets specific areas (e.g., tumors, infected tissues),
- Reduces side effects on healthy tissues,
- Enhances drug efficacy.

Question 16

What is an example of a polymer-drug conjugate used in site-directed drug delivery?

Answer 16

An example is a block copolymer of poly(ethylene glycol) (PEG) and poly(aspartic acid), where PEG provides solubility and the poly(amino acid) attaches to an anticancer drug.