Polythiophenes (PTs) are polymerized thiophenes, a sulfur heterocycle. The parent PT is an insoluble colored solid with the formula (C4H2S)n. The rings are linked through the 2- and 5-positions. Poly(alkylthiophene)s have alkyl substituents at the 3- or 4-position(s). They are also colored solids, but tend to be soluble in organic solvents.
Polythiophenes demonstrate interesting optical properties resulting from their conjugated backbone, as demonstrated by the fluorescence of a substituted polythiophene solution under UV irradiation.
AFM image of poly(3-decylthiophene-2,5-diyl) on hexagonal boron nitride (top-right inset).
A polymer
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 and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals.
Appearance of real linear polymer chains as recorded using an atomic force microscope on a surface, under liquid medium. Chain contour length for this polymer is ~204 nm; thickness is ~0.4 nm.
A polyethylene sample that has necked under tension
A plastic item with thirty years of exposure to heat and cold, brake fluid, and sunlight. Notice the discoloration and crazing of the material (compared with replacement item in foreground).
Chlorine attack of acetal resin plumbing joint
