Unit 2 Materials Chemistry Polymers

Flashcards for Materials Chemistry Polymers review.

Polymer

Giant molecules formed by the combination of several simple molecules having two or more binding sites linked through covalent bonding.

Monomer

Simple molecules which are repeating units of the polymer.

Degree of Polymerization (DP)

The number which expresses the total number of repeating units (n) in the polymer chain.

High Polymers

Polymers with a large number of repeating units.

Oligomers

Polymers with a lower number of repeating units.

Functionality

The total number of functional groups, bonding sites, or reactive sites present in the monomer.

Linear Polymers

Polymers consist of long, unbranched chains of monomers linked together in a straight line.

Branched Polymers

Polymers have a main linear backbone with additional side chains or branches attached to it.

Network (Cross-linked) Polymers

Polymers are formed when linear or branched polymer chains are chemically connected at various points along their lengths, creating a three- dimensional network structure.

Strength of Polymer

Mainly determined by the magnitude and distribution of attraction forces between the polymer chains. These attractive forces are of two different types viz., primary or covalent bond and secondary or intermolecular forces.

Slipping Power

Movement of molecules one over the other when a polymer is under stress.

Plastic Deformation

When a polymer is subjected to some stress in the form of heat or pressure or both, permanent deformation in shape takes place.

Amorphous State

Characterized by completely random arrangement of molecules.

Crystalline Form

Characterized by regular arrangement of molecules.

Chemical Resistance of Polymer

Depends upon the chemical nature of monomers and their molecular arrangement.

Elasticity

Elastic nature in polymers results due to the uncoiling and recoiling of the molecular chains on the application of force.

Glass Transition Temperature (Tg)

The temperature below which an amorphous polymer is brittle, hard, and glassy and above the temperature it becomes flexible, soft, and rubbery.

Number-Average Molecular Weight

Defined as the total mass of all the molecules in a polymer sample divided by the total number of molecules present.

Weight-Average Molecular Weight

The sum of the fractional masses that each molecule contributes to the average according to the ratio of its mass to that of the whole sample.

Viscometry

The molecular weight obtained by this technique is the viscosity average molecular weight, Mv.

Engineering Polymers

Represent a specialized class of materials designed to meet stringent performance requirements in demanding applications.

Polyamides

Synthetic polymers characterized by the presence of repeating amide (–CONH– ) linkages along the polymer chain.

Polyesters

A category of polymers that contain the ester functional group in their main chain and are widely used in a variety of applications due to their versatile properties.

Epoxies

Class of reactive prepolymers and polymers which contain epoxide groups and are known for their excellent mechanical properties, strong adhesion, and resistance to chemical and environmental degradation.

Biodegradable Polymers

A class of polymers that can be broken down by microorganisms, such as bacteria, fungi, and algae, into harmless byproducts like water, carbon dioxide, and methane, under aerobic or anaerobic conditions.

Poly(lactic acid) (PLA)

A biodegradable and bioactive thermoplastic derived from renewable resources such as corn starch, sugarcane, or cassava roots, reducing dependence on fossil fuels.

Polyhydroxyalkanoates (PHAs)

A class of biodegradable and biocompatible polymers produced by various microorganisms.

Conducting Polymers

Organic polymers that conduct electricity and combine the mechanical properties of plastics with high electrical conductivities.

Intrinsically Conducting Polymers

A polymer whose backbones or associated groups consist of delocalized electron pair or residual charge.

Doped Conducting Polymers

Obtained by exposing a polymer to a charged transfer agent in either gas phase or in solution to increase conductivity.

Extrinsically Conducting Polymers

These polymers possess their conductivity due to the presence of externally added ingredients in them.

Smart Polymers

Materials that can undergo reversible changes in their physical or chemical properties in response to external stimuli.

Temperature-Responsive Polymers

Intelligent materials capable of adjusting their properties in response to temperature variations.

Electro-Responsive Polymers

Smart polymers capable of dynamically adjusting their physicochemical characteristics upon exposure to electric signals.

Photo-Responsive Polymers

Materials that undergo changes in their physical or chemical properties when exposed to light.

Filtration Membrane

A semi-permeable thin layer of material capable of separating contaminants due to their physical/chemical characteristics.

Polymeric Biomaterial

Materials used in medical applications that are composed of polymers, which are long chains of repeating molecular units.

Self-Healing Materials

Artificial or synthetically created substances that have the built-in ability to automatically repair damages to themselves without any external diagnosis of the problem or human intervention.

Nanomaterials

Materials which have at least one of their dimension in the nanometer (1 nm= 10−9 m) range.

Liquid Crystals (LC)

A state of matter between solids and liquids with both the properties.

OLEDs

Organic electroluminescence (EL) is the electrically driven light-emitting phenomenon from organic materials

MicroLEDs

MicroLEDs represent a cutting-edge display technology that offers significant improvements over traditional display types such as OLEDs and LCDs.

Foldable Displays

Foldable displays represent an innovative advancement in display technology, allowing screens to bend, fold, and flex without compromising functionality.