Depolymerizable polymers or Low-Ceiling Temperature Polymers refer to
polymeric materials that can undergo
depolymerization Depolymerization (or depolymerisation) is the process of converting a polymer into a monomer or a mixture of monomers. This process is driven by an increase in entropy.
Ceiling temperature
The tendency of polymers to depolymerize is indicated by ...
to revert the materials to their
monomer
In chemistry, a monomer ( ; '' mono-'', "one" + ''-mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.
Classification
...
s at relatively low temperatures, such as
room temperature. For example, the
ceiling temperature Ceiling temperature (T_c) is a measure of the tendency of a polymer to revert to its constituent monomers. When a polymer is at its ceiling temperature, the rate of polymerization and depolymerization of the polymer are equal. Generally, the cei ...
T
c for
formaldehyde
Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
is 119 °C, and that for
acetaldehyde is -39 °C.
Introduction
Unlike stable
polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
s such as
PVCs
PVCS Version Manager (originally named Polytron Version Control System) is a software package by Serena Software Inc., for version control of source code files.
PVCS follows the "locking" approach to concurrency control; it has no ''merge'' opera ...
that have high
thermal stability
In thermodynamics, thermal stability describes the stability of a water body and its resistance to mixing.Schmidt, W. 1928. Über Temperatur und Stabilitätsverhältnisse von Seen. Geogr. Ann 10: 145 - 177. It is the amount of work needed to t ...
, depolymerizable polymers and closely related self-immolative polymers can be triggered by stimuli to break fast under moderate to low temperatures. The first type of polymers, poly (
olefin sulfone
In organic chemistry, a sulfone is a organosulfur compound containing a sulfonyl () functional group attached to two carbon atoms. The central hexavalent sulfur atom is double-bonded to each of two oxygen atoms and has a single bond to each of ...
), was reported by Snow and Frey in 1943. It was further confirmed and explained in terms of the
thermodynamics
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of th ...
of a reversible
propagation
Propagation can refer to:
* Chain propagation in a chemical reaction mechanism
*Crack propagation, the growth of a crack during the fracture of materials
* Propaganda, non-objective information used to further an agenda
* Reproduction, and other fo ...
step by
Dainton and Ivin. Closely related to depolymerizable polymers, self-immolative polymers can also irreversibly disassemble into their constituent parts in response to stimuli such as temperature, biological inputs or pH.
Applications
The first application of depolymerizable polymers is in
transient electronics. Over the past several decades in the
electronics industry, polymer research has focused on developing and optimizing durable and high-strength polymeric materials for use in electronics. Demand for
consumer electronics
Consumer electronics or home electronics are electronic ( analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. Usuall ...
and the generation of
electronic waste
Electronic waste or e-waste describes discarded electrical or electronic devices. Used electronics which are destined for refurbishment, reuse, resale, salvage recycling through material recovery, or disposal are also considered e-waste. Inform ...
has also prompted research into employing depolymerization methods to generate more sustainable and recyclable polymers. For example, a group of researchers employed light-sensitive poly(
phthalaldehyde
Phthalaldehyde (sometimes also ''o''-phthalaldehyde or ''ortho''-phthalaldehyde, OPA) is the chemical compound with the formula C6H4(CHO)2. It is one of three isomers of benzene dicarbonyl, dicarbaldehyde, related to phthalic acid. This pale yell ...
) as
substrate materials for
circuits. The destruction of the
polymer substrate was triggered by
UV irradiation
Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (ultraviolet C or UV-C) light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unabl ...
(~379 nm).
Other applications include controlled release of small molecules, and as stimuli-responsive photoresists for lithography.
References
Polymers
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