p. 315; cf. p. 179: “chain polymerisation”) and drew a comparison with a box of
matches that has been set on fire: “just one match has to be ignited to set all the
matches on fire” [4, p. 95].
2.5 Carbon Double Bonds of Critical Importance
It is not, however, the case that all monomers are capable of forming macromolecules. (Chemically unsaturated) hydrocarbons are what primarily have the ability to
create a polymer chain. In them, the carbon atoms have multiple bonds and the
number of hydrogen atoms is reduced accordingly:
• Single carbon bond, e.g. ethane: each of the two carbon atoms has bonds to the
other carbon atom as well as to three hydrogen atoms. As long as no atom is
removed, no bonds are available to join a polymer chain (saturated state).
• Double carbon bond, e.g. ethylene: there are two bonds between the carbon
atoms. One is easy to break (unsaturated state), so that the molecule can join a
polymer chain. Rubber, for example, has numerous ethylene bonds (see [13],
p. 785, quoted in [16], p. 55; cf. [18], p. 240, footnote 42).
• Triple carbon bond, e.g. acetylene: the triple bond of acetylene is so easy to
break that the molecule falls apart explosively; for this reason, it is only suitable
as the component of a polymer chain to a very limited extent.
Unsaturated raw materials with at least one carbon double bond are therefore the
primary candidates for the production of macromolecules. This bond can be opened
(“activated”) under the influence of heat, high pressure or auxiliary agents known as
“initiators” (see Appendix 2); it then tries to find other molecules that are capable of
forming a bond. This initial step is known as the “start reaction”. The chain
formation process (polymerisation) that then follows leads to polymers/plastics
with very different properties, depending on when the process is terminated. The
termination reaction can be initiated in a controlled fashion, e.g. by adding water,
atmospheric oxygen (cf. [1], p. 176) or solvents. In this context, a hydrogen atom
changes its position and a saturated giant molecule is created. Polymerisability and
polymerisation speed do not therefore depend solely on the structure of the molecules; they are also influenced to a large extent by agents that are added to initiate
(start reaction), maintain (growth reaction) or end (termination reaction) polymerisation. Staudinger [1], p. 171) says that substituents “can both increase [. . .] and
decrease polymerisability (cf. [10], p. 7) thanks to their impact on the carbon double
bond. Oxygen, for example, turns “soluble rubber with unlimited swelling properties [. . .] into rubber that is insoluble and only swells to a limited extent [. . .]. The
soluble rubber remains unchanged in nitrogen atmospheres, on the other hand”
([10], p. 26 and cf. [1], p. 330 about polystyrene). What is particularly spectacular in
this context is that even “minute amounts of substances can lead to exceptionally
large changes in the physical properties (of macromolecular substances, editor’s
note)” [1, p. 329]. “In certain circumstances, it is sufficient for the reactive
Courageous Questioning of Established Thinking: The Life and Work of Hermann. . .
93
matches that has been set on fire: “just one match has to be ignited to set all the
matches on fire” [4, p. 95].
2.5 Carbon Double Bonds of Critical Importance
It is not, however, the case that all monomers are capable of forming macromolecules. (Chemically unsaturated) hydrocarbons are what primarily have the ability to
create a polymer chain. In them, the carbon atoms have multiple bonds and the
number of hydrogen atoms is reduced accordingly:
• Single carbon bond, e.g. ethane: each of the two carbon atoms has bonds to the
other carbon atom as well as to three hydrogen atoms. As long as no atom is
removed, no bonds are available to join a polymer chain (saturated state).
• Double carbon bond, e.g. ethylene: there are two bonds between the carbon
atoms. One is easy to break (unsaturated state), so that the molecule can join a
polymer chain. Rubber, for example, has numerous ethylene bonds (see [13],
p. 785, quoted in [16], p. 55; cf. [18], p. 240, footnote 42).
• Triple carbon bond, e.g. acetylene: the triple bond of acetylene is so easy to
break that the molecule falls apart explosively; for this reason, it is only suitable
as the component of a polymer chain to a very limited extent.
Unsaturated raw materials with at least one carbon double bond are therefore the
primary candidates for the production of macromolecules. This bond can be opened
(“activated”) under the influence of heat, high pressure or auxiliary agents known as
“initiators” (see Appendix 2); it then tries to find other molecules that are capable of
forming a bond. This initial step is known as the “start reaction”. The chain
formation process (polymerisation) that then follows leads to polymers/plastics
with very different properties, depending on when the process is terminated. The
termination reaction can be initiated in a controlled fashion, e.g. by adding water,
atmospheric oxygen (cf. [1], p. 176) or solvents. In this context, a hydrogen atom
changes its position and a saturated giant molecule is created. Polymerisability and
polymerisation speed do not therefore depend solely on the structure of the molecules; they are also influenced to a large extent by agents that are added to initiate
(start reaction), maintain (growth reaction) or end (termination reaction) polymerisation. Staudinger [1], p. 171) says that substituents “can both increase [. . .] and
decrease polymerisability (cf. [10], p. 7) thanks to their impact on the carbon double
bond. Oxygen, for example, turns “soluble rubber with unlimited swelling properties [. . .] into rubber that is insoluble and only swells to a limited extent [. . .]. The
soluble rubber remains unchanged in nitrogen atmospheres, on the other hand”
([10], p. 26 and cf. [1], p. 330 about polystyrene). What is particularly spectacular in
this context is that even “minute amounts of substances can lead to exceptionally
large changes in the physical properties (of macromolecular substances, editor’s
note)” [1, p. 329]. “In certain circumstances, it is sufficient for the reactive
Courageous Questioning of Established Thinking: The Life and Work of Hermann. . .
93