Chemistry End-Sem
Question Bank
Unit 03 • Unit 04 • Unit 05 • Unit 06
Unit No:- 03
1. How copolymer of hydroxybutyrate and hydroxyvalerate is produced? Give the
Structure, property and application of copolymer.
Copolymer of hydroxybutyrate and hydroxyvalerate, also known as polyhydroxyalkanoate
(PHA), is produced through microbial fermentation. The process involves utilizing certain
bacteria, such as Cupriavidus necator or Alcaligenes eutrophus, that have the ability to
produce PHA as a storage material. These bacteria are grown on a suitable carbon source,
typically a renewable feedstock like plant oils or sugars, under controlled conditions.
During fermentation, the bacteria convert the carbon source into PHA through their metabolic
pathways. The composition of the copolymer, specifically the ratio of hydroxybutyrate (HB) to
hydroxyvalerate (HV) units, can be controlled by adjusting the feedstock composition or by
genetic engineering of the bacteria.
The structure of the copolymer varies depending on the ratio of HB to HV units. The presence
of hydroxyvalerate units in the copolymer introduces branching and increases the flexibility of
the polymer chain. As a result, the copolymer exhibits improved ductility and processability
compared to the homopolymer of hydroxybutyrate.
Properties of copolymer of hydroxybutyrate and hydroxyvalerate include:
1. Biodegradability: PHA copolymers are biodegradable under various environmental
conditions, making them suitable for applications requiring sustainable and environmentally
friendly materials.
2. Thermoplastic behavior: The copolymer can be melt-processed and exhibits thermoplastic
behavior, allowing for the fabrication of a wide range of products through techniques such as
injection molding and extrusion.
pg. 1
https://msha.ke/btechnotes
,3. Mechanical properties: The mechanical properties of the copolymer can be tailored by
adjusting the HB/HV ratio. Increasing the hydroxyvalerate content enhances the flexibility and
impact resistance of the copolymer.
4. Barrier properties: PHA copolymers have good barrier properties against oxygen and
moisture, making them suitable for packaging applications.
5. Biocompatibility: The copolymer is biocompatible, non-toxic, and has low immunogenicity,
making it suitable for various medical and pharmaceutical applications.
Applications of copolymer of hydroxybutyrate and hydroxyvalerate include:
1. Packaging materials: PHA copolymers are used in the production of films, coatings, and
packaging materials due to their biodegradability and barrier properties.
2. Biomedical applications: The copolymer is used in medical devices, tissue engineering
scaffolds, drug delivery systems, and sutures due to its biocompatibility and biodegradability.
3. Agricultural applications: PHA copolymers are used in agricultural films, mulching films, and
controlled-release fertilizers, providing an eco-friendly alternative to conventional plastics.
4. Consumer goods: The copolymer is used in the production of disposable items such as
cutlery, cups, and trays.
5. Industrial applications: PHA copolymers find applications in areas such as coatings,
adhesives, and additives for enhancing the properties of other materials.
Overall, copolymers of hydroxybutyrate and hydroxyvalerate offer a versatile and sustainable
alternative to traditional plastics, with a wide range of applications in various industries.
2. What are conducting polymers? What are the structure requirements for a polymer to
be conducting? Explain intrinsically and extrinsically conducting polymers with
example
Conducting polymers are a special class of polymers that exhibit electrical conductivity. Unlike
traditional polymers, which are typically insulators or have very low conductivity, conducting
polymers have the ability to conduct electric current. This unique property makes them
attractive for various applications in electronics, energy storage, sensors, and other fields.
pg. 2
https://msha.ke/btechnotes
,Structure requirements for a polymer to be conducting:
1. Conjugated π-electron system: The polymer must possess a conjugated π-electron system,
which allows for the delocalization of electrons along the polymer chain. This delocalization
enables the movement of charge carriers and facilitates electrical conductivity.
2. Alternating single and double bonds: The presence of alternating single and double bonds
along the polymer backbone creates a system of overlapping π-orbitals. This delocalized π-
electron system contributes to the polymer's conductivity.
Intrinsically conducting polymers (ICPs):
Intrinsically conducting polymers are inherently conductive without the need for additional
dopants or modifications. These polymers can exhibit high conductivity levels even in their
pristine form. Examples of intrinsically conducting polymers include polyaniline (PANI),
polypyrrole (PPy), and polythiophene (PTh). They are often referred to as "self-doped"
polymers, as they contain ionizable groups within their structure, allowing them to conduct
electricity without the need for external doping.
Extrinsically conducting polymers (ECPs):
Extrinsically conducting polymers, also known as doped polymers, require the addition of
dopants or other chemical modifications to enhance their conductivity. Dopants are
substances that donate or accept charge carriers, effectively increasing the number of charge
carriers in the polymer. Common dopants used include acids, bases, and oxidizing or reducing
agents. Examples of extrinsically conducting polymers include doped versions of polyaniline,
polypyrrole, and polythiophene. The conductivity of ECPs can be tuned by varying the dopant
concentration.
Overall, conducting polymers offer the unique advantage of combining the mechanical
flexibility and processability of polymers with electrical conductivity. This property opens up
possibilities for their use in electronic devices, such as organic transistors, flexible displays, and
organic solar cells, as well as in energy storage systems, sensors, and electrochemical devices.
3. What are biodegradable polymers? Give important feature of biodegradable polymer
How Biodegradable polymers are classified? Give suitable example for each type
Biodegradable polymers are a type of polymer that can be broken down into simpler
compounds by biological processes, such as the action of microorganisms, enzymes, or other
pg. 3
https://msha.ke/btechnotes
, living organisms. They have gained significant attention due to their ability to degrade and be
assimilated by the natural environment, offering potential solutions to the problem of plastic
waste accumulation. Here are some important features of biodegradable polymers:
1. Environmental Impact: Biodegradable polymers have the potential to reduce the
environmental impact of plastic waste by breaking down into non-toxic byproducts and being
incorporated into natural cycles.
2. Renewable Sources: Many biodegradable polymers can be derived from renewable
resources, such as plant starches, cellulose, or bio-based monomers, reducing reliance on
fossil fuels.
3. Customizable Properties: Biodegradable polymers can be designed with specific properties,
such as mechanical strength, flexibility, and degradation rate, to suit various applications.
4. Versatility: Biodegradable polymers can be processed using conventional polymer
processing techniques, allowing for their incorporation into a wide range of products
Biodegradable polymers are classified into different types based on their chemical structure
and degradation mechanisms. Some common types of biodegradable polymers and their
examples include:
1. Polyesters:
- Poly(lactic acid) (PLA): Derived from renewable sources, such as corn or sugarcane, PLA is
widely used in packaging, disposable products, and biomedical applications.
- Polyhydroxyalkanoates (PHA): Produced by bacterial fermentation, PHAs exhibit a range of
properties and are used in applications such as packaging, agriculture, and biomedical devices.
2. Polysaccharides:
- Starch: A natural polymer derived from plants, starch-based biodegradable materials are
used in packaging, agricultural films, and food containers.
- Chitosan: Derived from chitin, a natural polymer found in the shells of crustaceans,
chitosan-based polymers have applications in wound healing, drug delivery, and tissue
engineering.
pg. 4
https://msha.ke/btechnotes
Question Bank
Unit 03 • Unit 04 • Unit 05 • Unit 06
Unit No:- 03
1. How copolymer of hydroxybutyrate and hydroxyvalerate is produced? Give the
Structure, property and application of copolymer.
Copolymer of hydroxybutyrate and hydroxyvalerate, also known as polyhydroxyalkanoate
(PHA), is produced through microbial fermentation. The process involves utilizing certain
bacteria, such as Cupriavidus necator or Alcaligenes eutrophus, that have the ability to
produce PHA as a storage material. These bacteria are grown on a suitable carbon source,
typically a renewable feedstock like plant oils or sugars, under controlled conditions.
During fermentation, the bacteria convert the carbon source into PHA through their metabolic
pathways. The composition of the copolymer, specifically the ratio of hydroxybutyrate (HB) to
hydroxyvalerate (HV) units, can be controlled by adjusting the feedstock composition or by
genetic engineering of the bacteria.
The structure of the copolymer varies depending on the ratio of HB to HV units. The presence
of hydroxyvalerate units in the copolymer introduces branching and increases the flexibility of
the polymer chain. As a result, the copolymer exhibits improved ductility and processability
compared to the homopolymer of hydroxybutyrate.
Properties of copolymer of hydroxybutyrate and hydroxyvalerate include:
1. Biodegradability: PHA copolymers are biodegradable under various environmental
conditions, making them suitable for applications requiring sustainable and environmentally
friendly materials.
2. Thermoplastic behavior: The copolymer can be melt-processed and exhibits thermoplastic
behavior, allowing for the fabrication of a wide range of products through techniques such as
injection molding and extrusion.
pg. 1
https://msha.ke/btechnotes
,3. Mechanical properties: The mechanical properties of the copolymer can be tailored by
adjusting the HB/HV ratio. Increasing the hydroxyvalerate content enhances the flexibility and
impact resistance of the copolymer.
4. Barrier properties: PHA copolymers have good barrier properties against oxygen and
moisture, making them suitable for packaging applications.
5. Biocompatibility: The copolymer is biocompatible, non-toxic, and has low immunogenicity,
making it suitable for various medical and pharmaceutical applications.
Applications of copolymer of hydroxybutyrate and hydroxyvalerate include:
1. Packaging materials: PHA copolymers are used in the production of films, coatings, and
packaging materials due to their biodegradability and barrier properties.
2. Biomedical applications: The copolymer is used in medical devices, tissue engineering
scaffolds, drug delivery systems, and sutures due to its biocompatibility and biodegradability.
3. Agricultural applications: PHA copolymers are used in agricultural films, mulching films, and
controlled-release fertilizers, providing an eco-friendly alternative to conventional plastics.
4. Consumer goods: The copolymer is used in the production of disposable items such as
cutlery, cups, and trays.
5. Industrial applications: PHA copolymers find applications in areas such as coatings,
adhesives, and additives for enhancing the properties of other materials.
Overall, copolymers of hydroxybutyrate and hydroxyvalerate offer a versatile and sustainable
alternative to traditional plastics, with a wide range of applications in various industries.
2. What are conducting polymers? What are the structure requirements for a polymer to
be conducting? Explain intrinsically and extrinsically conducting polymers with
example
Conducting polymers are a special class of polymers that exhibit electrical conductivity. Unlike
traditional polymers, which are typically insulators or have very low conductivity, conducting
polymers have the ability to conduct electric current. This unique property makes them
attractive for various applications in electronics, energy storage, sensors, and other fields.
pg. 2
https://msha.ke/btechnotes
,Structure requirements for a polymer to be conducting:
1. Conjugated π-electron system: The polymer must possess a conjugated π-electron system,
which allows for the delocalization of electrons along the polymer chain. This delocalization
enables the movement of charge carriers and facilitates electrical conductivity.
2. Alternating single and double bonds: The presence of alternating single and double bonds
along the polymer backbone creates a system of overlapping π-orbitals. This delocalized π-
electron system contributes to the polymer's conductivity.
Intrinsically conducting polymers (ICPs):
Intrinsically conducting polymers are inherently conductive without the need for additional
dopants or modifications. These polymers can exhibit high conductivity levels even in their
pristine form. Examples of intrinsically conducting polymers include polyaniline (PANI),
polypyrrole (PPy), and polythiophene (PTh). They are often referred to as "self-doped"
polymers, as they contain ionizable groups within their structure, allowing them to conduct
electricity without the need for external doping.
Extrinsically conducting polymers (ECPs):
Extrinsically conducting polymers, also known as doped polymers, require the addition of
dopants or other chemical modifications to enhance their conductivity. Dopants are
substances that donate or accept charge carriers, effectively increasing the number of charge
carriers in the polymer. Common dopants used include acids, bases, and oxidizing or reducing
agents. Examples of extrinsically conducting polymers include doped versions of polyaniline,
polypyrrole, and polythiophene. The conductivity of ECPs can be tuned by varying the dopant
concentration.
Overall, conducting polymers offer the unique advantage of combining the mechanical
flexibility and processability of polymers with electrical conductivity. This property opens up
possibilities for their use in electronic devices, such as organic transistors, flexible displays, and
organic solar cells, as well as in energy storage systems, sensors, and electrochemical devices.
3. What are biodegradable polymers? Give important feature of biodegradable polymer
How Biodegradable polymers are classified? Give suitable example for each type
Biodegradable polymers are a type of polymer that can be broken down into simpler
compounds by biological processes, such as the action of microorganisms, enzymes, or other
pg. 3
https://msha.ke/btechnotes
, living organisms. They have gained significant attention due to their ability to degrade and be
assimilated by the natural environment, offering potential solutions to the problem of plastic
waste accumulation. Here are some important features of biodegradable polymers:
1. Environmental Impact: Biodegradable polymers have the potential to reduce the
environmental impact of plastic waste by breaking down into non-toxic byproducts and being
incorporated into natural cycles.
2. Renewable Sources: Many biodegradable polymers can be derived from renewable
resources, such as plant starches, cellulose, or bio-based monomers, reducing reliance on
fossil fuels.
3. Customizable Properties: Biodegradable polymers can be designed with specific properties,
such as mechanical strength, flexibility, and degradation rate, to suit various applications.
4. Versatility: Biodegradable polymers can be processed using conventional polymer
processing techniques, allowing for their incorporation into a wide range of products
Biodegradable polymers are classified into different types based on their chemical structure
and degradation mechanisms. Some common types of biodegradable polymers and their
examples include:
1. Polyesters:
- Poly(lactic acid) (PLA): Derived from renewable sources, such as corn or sugarcane, PLA is
widely used in packaging, disposable products, and biomedical applications.
- Polyhydroxyalkanoates (PHA): Produced by bacterial fermentation, PHAs exhibit a range of
properties and are used in applications such as packaging, agriculture, and biomedical devices.
2. Polysaccharides:
- Starch: A natural polymer derived from plants, starch-based biodegradable materials are
used in packaging, agricultural films, and food containers.
- Chitosan: Derived from chitin, a natural polymer found in the shells of crustaceans,
chitosan-based polymers have applications in wound healing, drug delivery, and tissue
engineering.
pg. 4
https://msha.ke/btechnotes
