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Chapter: Pharmaceutical Drugs and Dosage: Pharmaceutical polymers

Pharmaceutical Drugs and Dosage: Pharmaceutical polymers - Review questions answers


Review questions

 

11.1 Which property is NOT TRUE for poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) block copolymers?

A.      Surfactant

B.      Forms micelles

C.      Biodegradable

D.      Thermosensitive

E.       All of the above

F.       None of the above

11.2 Which of the following is TRUE for biomaterials?

A.      The greater the degree of crystallinity of the polymer, the lower the rate of dissolution.

B.      Molecular weight and molecular weight distribution affect sol-vent penetration and crystallinity.

C.      Increase in the main-chain polarity increases the glass transition temperature of a polymer.

D.      Modification of biomaterial surfaces with polyethylene glycol minimizes protein adsorption and/or platelet adhesion.

E.       All of the above.

F.       None of the above.

11.3 Define the following nomenclatures using chemical structures of commonly used polymers:

A.      Biomaterials and biocompatibility

B.      Block and graft copolymers

C.      Repeating unit and end group

D.      Monomer and oligomer

11.4 What is the degree of polymerization (DP) of (a) a sample of poly(methyl methacrylate) with average molecular weight of 50,000, and (b) a sample of poly(tetramethylene-m-benzenesulfonamide) with average molecular weight of 26,000?

11.5 Suppose we have a polymer sample consisting of 9 moles with molec-ular weight 15,000 and 5 moles with molecular weight 25,000. What is the number average molecular weight (Mn) and the weight average molecular weight (Mw)?

Answers:

11.1 C.

11.2 E.

11.3 A. Biomaterials and biocompatibility: A biomaterial is a natural or synthetic polymer used as a device or carrier, intended to interact with biological systems. Biocompatibility is the ability of a mate-rial to perform with an appropriate host response in a specific application.

B. Block and graft copolymers: Two or more monomers are employed for synthesizing copolymers. In copolymers, the monomeric units may be distributed randomly (random copolymer), in an alternat-ing fashion (alternating copolymer), or in blocks (block copoly-mer). A graft copolymer consists of one polymer branching from the backbone of the other.

C. Repeating unit and end group: The structural unit enclosed by brackets or parentheses is referred to as the repeating unit (or mono-meric unit). To accent the repetition, a subscript n is frequently placed after the closing bracket, for example, –[–CH2CH2–]n–. End groups are the structural units that terminate polymer chains.

D. Monomer and oligomer: Polymers are synthesized from simple molecules called monomers by a process called polymerization. If only a few monomer units are joined together, the resulting low-molecular weight polymer is called an oligomer.

11.4 A. Molecular weight methylmethacrylate = 100, DP= 50,000/100 = 500; molecular weight tetramethylene-m-benzenesulfonamide = 211, DP = 26,000/211 = 123

Mn = (15,000 * 9 + 25,000 * 5)/(9 + 5)= 18571.4

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