exam 3 lecture 4 Flashcards

1
Q

molecular weight

A

number average (Mn)
weight average (Mw)

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2
Q

molecular weight distribution

A

monodispersed: Mn = Mw –> narrow distribution
polydispersed: Mw&raquo_space; Mn –> broad distribution

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3
Q

crystalline

A

linear polymer
polymer can pack together in regular arrays at T<Tm
manifests sharp Tm
good barrier to drug diffusion

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4
Q

amorphous

A

more common
polymers with irregular structure
polymers forms “glass” at T«Tg
softens over a wide temperature range

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5
Q

Tg (glass transition temp)

A

temperature range where polymer changes from hard, rigid, glassy to pliable, compliant, rubbery state
T«Tg = hard glass
T»Tg = rubbery and flow

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6
Q

chewable dosage forms Tg

A

have low Tg –> the gum softens at mouth temperature
ex - nicotine gum

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7
Q

factors affecting Tg

A

polymer length: longer is higher Tg
side chains: bulkier is higher Tg
crosslinking: more crosslinked is higher Tg
plasticizers: increase entropy and mobility of polymer chains –> lower Tg when included in polymer products

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8
Q

plasticizers

A

increase entropy and mobility of polymer chains –> lower Tg when included in polymer products

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9
Q

mechanical properties graph

A

stress (force/area) vs strain (deformation)

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10
Q

mechanical properties (EXAM QUESTION)

A

slope (stress/strain): modulus (stiffness)
area under the curve: toughness
elastic polymers: fibers or highly crosslinked polymers
- linear stress vs strain curve up to a break point
rubbers or elastomers:
- may deform 10-15 times their original lengths

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11
Q

hydrogels

A

crosslinked hydrophillic polymers
- chemical gels + physical gels
swell rapidly when placed underwater
- chain-water interaction, electrostatic repulsion, osmotic forces
retain large volume of water in their structures

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12
Q

cellulose-based polymers

A

ethylcellulose (tab coating)
carboxymethyl cellulose ( superdisintigrant ; emulsifier)
hydroxypropyl methyl cellulose (tablet binder, coating)

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13
Q

hydrocolloids

A

alginic acid (thickening agent in suspension)
chitosan (mucoadhesive dosage forms)

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14
Q

water-soluble synthetic polymers

A

poly (ethylene glycol) (plasticizer, suppository base, stealth coating)
poly(vinyl alcohol) (tablet binder, coating)

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15
Q

water- insoluble synthetic polymers

A

poly(lactic-coglycolic acid) (controlled drug release)
polylactic acid (controlled drug release

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