Polymers: Chemistry & Physics of Modern Materials, 2nd edition, by J. M. G. Cowie
Various places: Cowie doesn't always follow organic chemistry conventions for drawing unsubstiututed cyclohexyl. These two structures mean the same thing (i.e., the small angular lines drawn indicate bonds to hydrogen).
Various places: Cowie uses angular brackets to indicate averages, for
example <Mn>. The more common convention is to place a bar
over the abbreviation:
Page 7: The polyester structure is missing a bond.
Page 7: The oxygen atoms are missing and the name is misspelled.
poly(vinylbutryal)
Page 10: The heterogeneity index is now commonly refered to as the polydispersity index.
Page 23, fourth item under General description: "Fluids which cure in the absence of air and in the presence of metals, heat, or UV light by the free radical mechanism."
Page 30: The mechanism of acylation of an amine by a carboxylic acid chloride is not SN2 (a single step reaction), but rather addition-elimination (two steps).
Page 37-8, section 2.9: "(2) The monomer... about 1
weight per cent..." The mole % is considerably higher.
"(3) Initiation, propagation, and termination reactions are essentially
identical in rate and mechanism." This statement is misleading. Chain
polymerizations have these three reactions; step polymerizations do not. A
better way to make the point would be to say that step polymerizations have
only one reaction, regardless of the size of the species involved.
"(5) Long reaction times and high conversions are necessary for the
production of a polymer with large xn." Yes, high
conversions are necessary, but the reaction time depends on kinetics of
individual reactions. Many of the common step polymerizations are slow, but
there are some fast ones, too. (Example: the nylon rope trick, in which long
chains are grown in seconds.)
"(6) Reaction rates are slow at ambient temperatures..." Again, there
are many exceptions to this. The prime consideration is to achieve a high
extent of conversion (>98%, typically). Some reactions get there slowly,
some quickly.
"(7) Activation energies are moderately high, and reactions are not
excessively exothermic." Again, this depends on the system, with many
exceptions to this statement.
Page 38-9: Polyimide synthesis takes place in two distinct stages,
not all at once as indicated. The initial stage is generally carried out at low
temperature in solution to produce a poly(amic acid). In most cases, this
polymeric intermediate is soluble, so films can be cast. In a second step, the
rings are closed with the expulsion of water to generate the final polyimide
structure. The imidization reaction is done by slowly heating to rather high
temperatures (200-300 °C), or by treating with a chemical dehydrating
agent (e.g., acetic anhydride). The more common polyimides are insoluble and
infusible after ring closure, although there are some examples (made with more
flexible monomers) in which the polyimides are soluble thermoplastics.
p 54: Cowie shows that the decomposition of benzoyl peroxide produces benzoyl radicals that lose CO2 to give phenyl radicals. Actually, the expulsion of CO2 turns out to be a minor side-reaction, and nearly all of the chains are initiated by the benzoyl radicals.
p 54: Cowie classifies azo compounds like AIBN as photochemical initiators. While certainly this is true (that is, AIBN will fragment under deep UV irradiation), these compounds are most often used as thermal initiators.
p 55: Persulphates (Americans spell this persulfates) are just an peculiar kind of peroxy initiators. The contain an O-O bond, and produce radical thermally. They just happen to be charged and inorganic, instead of uncharged and organic.
If you find any other errors in the textbook, be sure to report them to the instructors.
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