TLDR The study found that thioglycolic acid breaks down hair bonds more consistently than l-cysteine, which is less damaging to hair.
The study investigated the heterogeneous reaction between reducing agents (thioglycolic acid (TG) and l-cysteine (CYS)) and keratin fibers in human hair using Raman spectroscopy and microspectrophotometry. It was found that TG diffused into the hair and disconnected disulfide (–SS–) groups in a Fickian manner, penetrating beyond the cuticle into the cortex region. In contrast, CYS showed a slower reaction rate and limited penetration into the cortex due to electrostatic interactions with the fiber surface, resulting in less damage to the hair. The findings indicated that hair treated with CYS was less damaged compared to TG-treated hair.
45 citations,
December 2006 in “Biopolymers” Permanent waving weakens hair by altering its protein structure.
5 citations,
April 2005 in “Journal of applied polymer science” PEI diffuses into hair at a constant rate, and urea speeds up this process.
[object Object] 52 citations,
February 2005 in “Biopolymers” Chemical hair straightening changes hair proteins and mostly fixes broken bonds.
29 citations,
August 2005 in “Biopolymers” L-cysteine slows down the breaking of bonds in hair due to electrostatic interactions.
16 citations,
October 2003 in “Journal of applied polymer science” 2-iminothiorane hydrochloride improves hair waving permanence without damage.
4 citations,
August 2014 in “Journal of molecular structure” Chemical treatments on bleached black hair change its internal structure by breaking and reforming bonds, and treatments with hydrolyzed eggwhite protein help repair it.
[object Object] 45 citations,
December 2006 in “Biopolymers” Permanent waving weakens hair by altering its protein structure.
18 citations,
January 2008 in “Sen'i Gakkaishi” Thioglycolic acid and L-cysteine change hair structure differently during perms, affecting hair strength and curling efficiency.
