Page 697 - Carrahers_Polymer_Chemistry,_Eighth_Edition

660 Carraher’s Polymer Chemistry

Polyhydroxyalkanoates are viewed by microorganisms as an attainable energy source so are bio-
degradable. The end products under aerobic conditions are carbon dioxide and water, while methane
is produced in anaerobic environments. They can also degrade under simple physical conditions
with the ester moiety attacked by water, acid, and base.
Both nylon 9 and nylon 11 can be synthesized from biomaterials. Nylon 11 (19.57) is commer-
cially available and synthesized from monomers produced from vegetable oils, particularly from
the castor plant.

R
HN

(19.57)
R O
Nylon 11

DuPont has developed several polymers derived from monomers created from renewable resources.

Sorona, 3GT, is a thermoplastic polyester fiber based on the reaction between PDO, where the PDO
is created from corn, and terephthalic acid creating the PTT, 3GT (19.58). The corn is converted to
sugar and the sugar fermented in the presence of certain bacteria that convert it to PDO.

R O O
HO O
H O OH +
O O
O OH

R
PDO Terephthalic acid Poly(trimethylene terephtalate), 3GT
(19.58)

Genomatica is producing commercial quantities of the similar diol 1,4-butanediol (BDO) using
microbes. They continue to work on developing microbes that will produce BDO in larger yields
and from more diverse natural feedstocks.
Hytrel is a thermoplastic polyester and elastomer (TPC-ET) containing 20%–60% polyol,
Cerenol, derived from corn. Cerenol is synthesized from the self-condensation of PDO with itself
and includes a variety of polyols of different chain lengths with molecular weights from about
500–2,000. Below, 19.59 shows the formation of a trimethylene ether glycol from reaction with
three molecules of PDO. This diol is then reacted in the usual fashion giving polyesters with the
usual hard (terephthalic derived moiety) and soft (polyol derived moiety) segments.

HO OH
H O O O OH

PDO Trimethylene ether glycol
(19.59)

There are a variety of blends that are using various biomaterials, including celluloses and pro-
teins that are also being investigated and employed.
Succinic acid is an intermediary in the energy-producing Krebs cycle so its production by
microbes has been investigated. After several years of effort, several international groups are pro-
ducing it on a commercial basis. It can be used in polymer synthesis as well as in the production of
a variety of plasticizers.
Recently, some effort has focused on the synthesis of monomers employing enzymes. Currently,

the focus is on investigating enzymes that can carry out specific steps to convert various carbon-

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