Unhydrolysable glucose polymers
Encyclopedia
Unhydrolysable Glucose Polymers
Glucans are polysaccharide
of glucose
monomers linked by glycosidic bonds. Accordingly, polymers built up of carbohydrate
units bounded other than glycosodic bond are not considered as polysaccharides. Only four different types glucose-based polysaccharides are possible to be built: 1,6- (Starch
), 1,4- (Cellulose
), 1,3- (Laminarin
) and 1,2-bounded glucans.
Levoglucosan
is 1,6-anhydro derivative of glucose. It is one of the key products in thermal conversion of polysaccharides. Polysaccharides are not volatile at combustion temperature and propagation of fire in volume takes place due to combustion of volatile product of degradation of polysaccharides, mainly Levoglucosan. The position 2, 3, and 4 atoms carbon of Levoglucosan are available for design of polymers, which doesn’t belong to class of polysaccharides.
The first representatives of main chain unhydrolysable linear polymer made up of Levoglucosan units were synthesized in 1985 by anionic polymerization of 2,3-epoxy
derivatives of Levoglucosan (1,6;2,3-dianhydro-4-O-alkyl-b-D-mannopyranoses).
A wide range of unique monomers with different radical R can be synthesized according to. There were synthesized polymers with R= -CH3, -CH2CHCH2, and -CH2C6H5. Investigation of polymerization kinetic of those derivatives, molecular weight and molecular-weight distribution showed the polymerization has feature of Living Polymerization System. Process takes place without termination
and transfer
of polymer chain with degree polymerization equal mole ratio monomer
to initiator
. Accordingly, the upper value molecular weight polymer determines only degree of purification system what determine the presence in the system uncontrollable amount of terminators of polymer chains.
Poly(2-3)-D-glucose was synthesized proceeds by transformation of Benzyl (R= -CH2C6H5) functionalized polymer.
Polymerization of 3,4-epoxy Levoglucosan (1,6;3,4-dianhydro-2-O-alkyl-β-D-galactopyranose) results in formation 3,4-bounded Levoglucosan polymer
The presence of 1,6-anhydro structure in every unit of polymer chains allows to apply all specter of well developed methods of carbohydrate chemistry
with formation of highly intriguing biological application polymers.
The polymers are the only known regular polyethers built up of carbohydrate units in main polymer chain
.
Glucans are polysaccharide
Polysaccharide
Polysaccharides are long carbohydrate molecules, of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure,...
of glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
monomers linked by glycosidic bonds. Accordingly, polymers built up of carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
units bounded other than glycosodic bond are not considered as polysaccharides. Only four different types glucose-based polysaccharides are possible to be built: 1,6- (Starch
Starch
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
), 1,4- (Cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
), 1,3- (Laminarin
Laminarin
The molecule laminarin is a storage glucan found in brown algae. It is used as a carbohydrate food reserve in the same way that chrysolaminarin is used by phytoplankton. It is created by photosynthesis and is made up of β-glucan with β-linkages. It is a linear polysaccharide, with a β:β ratio...
) and 1,2-bounded glucans.
Levoglucosan
Levoglucosan
Levoglucosan is an organic compound with six carbon ring structure formed from the pyrolysis of carbohydrates, such as starch and cellulose...
is 1,6-anhydro derivative of glucose. It is one of the key products in thermal conversion of polysaccharides. Polysaccharides are not volatile at combustion temperature and propagation of fire in volume takes place due to combustion of volatile product of degradation of polysaccharides, mainly Levoglucosan. The position 2, 3, and 4 atoms carbon of Levoglucosan are available for design of polymers, which doesn’t belong to class of polysaccharides.
The first representatives of main chain unhydrolysable linear polymer made up of Levoglucosan units were synthesized in 1985 by anionic polymerization of 2,3-epoxy
Epoxy
Epoxy, also known as polyepoxide, is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of applications, including fiber-reinforced plastic materials and general purpose adhesives....
derivatives of Levoglucosan (1,6;2,3-dianhydro-4-O-alkyl-b-D-mannopyranoses).
A wide range of unique monomers with different radical R can be synthesized according to. There were synthesized polymers with R= -CH3, -CH2CHCH2, and -CH2C6H5. Investigation of polymerization kinetic of those derivatives, molecular weight and molecular-weight distribution showed the polymerization has feature of Living Polymerization System. Process takes place without termination
Termination
Termination may refer to:In science:*Termination codon, in molecular biology*Termination factor, in genetics, part of the process of transcribing RNA...
and transfer
Transfer
Transfer may refer to:* Transfer * Transfer * Transfer DNA, the transferred DNA of the tumor-inducing plasmid of some species of bacteria such as Agrobacterium tumefaciens* Transfer...
of polymer chain with degree polymerization equal mole ratio monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
to initiator
Initiator
An initiator can refer to:* A person that takes an initiative in making something happen.* Modulated neutron initiator, a neutron source used in some nuclear weapons...
. Accordingly, the upper value molecular weight polymer determines only degree of purification system what determine the presence in the system uncontrollable amount of terminators of polymer chains.
Poly(2-3)-D-glucose was synthesized proceeds by transformation of Benzyl (R= -CH2C6H5) functionalized polymer.
Polymerization of 3,4-epoxy Levoglucosan (1,6;3,4-dianhydro-2-O-alkyl-β-D-galactopyranose) results in formation 3,4-bounded Levoglucosan polymer
The presence of 1,6-anhydro structure in every unit of polymer chains allows to apply all specter of well developed methods of carbohydrate chemistry
Carbohydrate chemistry
Carbohydrate chemistry is a subdiscipline of chemistry primarily concerned with the synthesis, structure, and function of carbohydrate structures. Due to the general structure of carbohydrates, their synthesis is often preoccupied with the selective formation of glycosidic linkages and the...
with formation of highly intriguing biological application polymers.
The polymers are the only known regular polyethers built up of carbohydrate units in main polymer chain
.