Hydroxypropyl methylcellulose (HPMC) is a synthetic polymer that is derived from cellulose, which is a naturally occurring organic polymer that forms the cell walls of plants. HPMC is made by chemically modifying cellulose through a process called etherification.
In etherification, cellulose is treated with a mixture of propylene oxide and methyl chloride under controlled conditions to produce hydroxypropyl cellulose (HPC). HPC is then further modified by treating it with methanol and hydrochloric acid to produce HPMC.
The resulting HPMC product is a water-soluble, non-ionic polymer that has many useful properties, such as high water retention, good film-forming ability, and excellent thickening and stabilizing properties. These properties make HPMC a useful additive in a wide range of applications, such as construction materials, pharmaceuticals, and food products.
While HPMC is derived from cellulose, it is a synthetic polymer that is produced through a complex chemical process.