The common understanding that synthetic materials are entirely man-made, without any connection to the natural world, is a misconception. A synthetic material is any substance whose final form and properties are created through a deliberate chemical process. The starting point for nearly all synthetic materials is a natural resource, a substance extracted from the earth or harvested from biomass. The difference between a purely natural product and a synthetic one is the degree of chemical transformation applied to the raw material.
The Chemical Transformation of Natural Feedstocks
Synthetic materials are largely composed of polymers, which are long-chain molecules built from smaller repeating units called monomers. The creation of these materials involves taking a natural feedstock, breaking it down into these basic monomer building blocks, and then chemically reassembling them in a controlled environment. This process, known as polymerization, results in a final material with properties completely unlike the original resource.
The dominant feedstock for modern synthetic materials is fossil fuel—petroleum, natural gas, and coal. These substances are natural resources, formed over millions of years from the buried remains of ancient organic matter. Fossil fuels are rich in hydrocarbons, making them ideal precursors for the carbon-based structures of most polymers.
In a refinery, these raw hydrocarbons are converted into simpler molecules like ethylene and propylene through processes such as cracking. These smaller molecules serve as the monomers that are linked together to form the long polymer chains of plastics and other synthetics. This transformation is extensive, taking the complex mixture of crude oil and turning it into a uniform, highly engineered material.
Common Synthetic Materials and Their Resource Origins
Many widely used synthetic materials can be traced directly back to petrochemicals derived from crude oil and natural gas. Polyethylene (PE), the world’s most common plastic, and Polyvinyl Chloride (PVC) both begin with ethylene, a light hydrocarbon gas obtained from petroleum refining or natural gas processing. For PVC, ethylene is combined with chlorine to create an intermediate, which is then polymerized into the final plastic.
Nylon, a synthetic polyamide fiber, provides another clear example of this chemical journey. The monomers required to make Nylon are currently manufactured primarily using petrochemical precursors derived from crude oil. This demonstrates how complex synthetic fabrics rely on multiple, highly refined chemical steps originating from a fossil fuel base.
Synthetic rubber, such as Styrene-Butadiene Rubber (SBR), is a copolymer made from two different monomers, styrene and butadiene. Both components are products of the petrochemical industry, typically produced during the steam cracking of petroleum fractions. SBR was developed as a petroleum-based alternative to natural rubber, confirming that its structure is entirely synthesized from fossil fuel hydrocarbons.
The Semi-Synthetic Category: Modified Natural Polymers
A distinct category of materials, known as semi-synthetics, further clarifies the link between natural resources and manufactured goods. Unlike true synthetics, which are built from basic monomers, semi-synthetics start with a large, naturally existing polymer and chemically modify its structure to improve its performance. The polymer chain itself is not destroyed and rebuilt, but rather altered.
The most common example is rayon, often called viscose, which is derived from cellulose obtained from wood pulp. The cellulose is treated with chemicals to convert it into a soluble, viscous fluid called viscose. This fluid is then extruded and re-solidified in an acid bath, regenerating the cellulose into a fiber suitable for textiles.
Cellophane, a clear film used in packaging, is produced using a nearly identical chemical modification process of wood pulp cellulose. The difference between rayon and cellophane lies in the extrusion process: rayon is forced through a spinneret to create a fiber, while cellophane is forced through a thin slit to create a sheet. In both cases, the core molecular backbone is the natural polymer cellulose, but its form and properties have been chemically transformed for human use.