Chapter 8 Final Flashcards
What are some advanced applications of polymers beyond commodity products?
- 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).
What is the role of polymers in membrane science and technology?
- Separation of gases and liquids,
- Proton transport in fuel cells,
- Food packaging (barrier against moisture and oxygen)
What is permeability in polymers, and why is it important?
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.
What are the key properties required for polymers used in medical applications?
Polymers for medical applications must possess:
- Biocompatibility,
- Selective permeability,
- Ability to degrade,
- High strength or modulus.
What are some examples of polymers used in medical applications?
- PVC (polyvinyl chloride),
- PP (polypropylene),
- Acrylics,
- PS (polystyrene).
What is the role of polymers in kidney dialysis?
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).
What are the challenges associated with polymer membranes in kidney dialysis?
- Concentration polarization,
- Clogged pores due to the adsorption of plasma proteins.
What is controlled drug delivery, and why is it important?
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.
What are the two main types of controlled drug delivery systems?
- Controlled release: Maintains steady drug concentration over time.
- Site-directed delivery: Targets specific areas of the body (e.g., tumors, infected tissues).
What are some examples of controlled drug delivery systems?
- Micro-/nano-capsules,
- Micro-/nano-spheres,
- Polymer-drug conjugates,
- Micelles,
- Liposomes,
- Hydrogels.
What is a reservoir-type drug delivery system?
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.
What is a matrix-type drug delivery system?
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.
What is a polymer-degraded release system, and what polymer is commonly used?
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).
What is a hydrogel, and how is it used in drug delivery?
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).
What are the advantages of site-directed drug delivery?
Site-directed drug delivery:
- Targets specific areas (e.g., tumors, infected tissues),
- Reduces side effects on healthy tissues,
- Enhances drug efficacy.
What is an example of a polymer-drug conjugate used in site-directed drug delivery?
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.
