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Explore  /  Bis-Aminopropyl Diglycol Dimaleate
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Bis-Aminopropyl Diglycol Dimaleate

C
lead outcome
Topical (hair): overall as a bond-repair…
grades vary by outcome ↓
Small molecule (non-peptide)
also called — bis-aminopropyl diglycol dimaleate · maleic acid salt of bis-aminopropyl diglycol
hair conditioningfibre treatment
In brief

The molecule that created the bond-building category, sold on the proposition that it travels into the hair cortex and reconstructs the disulfide bridges that bleach destroys. When that proposition was examined independently on bleached human hair by Raman spectroscopy, cortical disulfide content did not increase and no direct evidence of the cross-linking reaction was found in the cortex. What the same study did find was real: the agent interacts with both cortex and cuticle, and treated fibres show a more regular, better-imbricated surface. So the substance is not inert and the handling benefit practitioners report is credible. It is the headline mechanism, and the premium attached to it, that the published record does not carry. Hair above the follicle cannot heal, so the honest ceiling for anything applied to it is reinforcement rather than repair.

Legal standing, by region
International
Lawful cosmetic ingredient

Lawful for cosmetic hair use internationally, including the EU and UK under Regulation (EC) No 1223/2009 as retained, and the United States, where it is used as a conventional cosmetic ingredient. It carries no listing in the restricted or prohibited annexes and is not a regulated substance.

Evidence, by outcome
How we grade →

An honest grade per outcome — drawn from the evidence, not any catalogue. Hype and undemonstrated marketing claims grade low.

OutcomeEvidence base · effectGrade
Topical (hair): overall as a bond-repair active
Real interaction with the fibre is established; the specific premium claim it is sold on is not. Surface-level improvement overlaps substantially with what conventional conditioning achieves at a fraction of the price.
One independent peer-reviewed structural study on bleached human hair using Raman and ATR/IR spectroscopy with SEM (Di Foggia 2021), testing a commercial formulation alongside model Michael-acceptor compounds. Beyond this, the dataset is manufacturer and patent literature. · The molecule demonstrably interacts with the hair fibre, modifying both cortex and cuticle regions, and treated fibres show a more regular surface with more imbricated cuticle scales under SEM.
C
Topical (hair): reconstruction of cortical disulfide bridges (the category claim)
The authors note the reaction cannot be entirely excluded, only that it was not detected. This is the claim the category's pricing rests on, and it remains unverified in independent published work.
Patent claim, tested independently by Di Foggia 2021 using Raman spectroscopy to interrogate the cortical region specifically. · Disulfide bridge content in the hair cortex did not increase after treatment, and the authors report no direct evidence of the sulfa-Michael cross-linking reaction occurring in the cortex.
D
Topical (hair): cuticle condition and surface regularity after bleaching
A cuticle-level effect, which is the level at which conditioning agents also operate. Measured on fibres, not as a blinded consumer outcome.
Scanning electron microscopy in the same independent structural study, alongside consistent practitioner reporting. · More regular fibre surface and better-imbricated cuticle scales following treatment of bleached hair.
B
Topical (hair): reduced breakage during and after chemical lifting
Consistent and plausible, but the supporting data is not independent. Reduced breakage preserves existing length and is routinely misread as growth.
Manufacturer data and broad practitioner consensus; no independent blinded trial with micro-tensile testing has been published. · Hair treated during or after bleaching is widely reported to snap less under combing and to handle with more resilience.
C
Marketing claim: permanent repair, hair restored to its undamaged state
Hair above the follicle is non-living keratin with no capacity to heal. Any effect is a bridge over damage, not a reversal of it.
Marketing claim. · No published evidence supports a permanent structural change; reported benefit reads session by session rather than accumulating toward a restored baseline.
D
Safety (topical, rinse-off and leave-on hair use)
Sensitisation is possible with any reactive cosmetic ingredient; scalp contact is incidental to the intended use on the fibre.
Long-standing lawful cosmetic use across major markets with no restriction under the applicable cosmetic regulations. · Used at low percentages in rinse-off and leave-on hair formats without regulatory restriction.
—
Disclosure

Vallydia sells its own cosmetic serums, and some ingredients graded here belong to the same categories as those products. Grades are drawn from the published evidence by the method we publish, and applied to our own ingredients on the same terms — our copper-peptide serum is graded no more kindly than the peptides it competes with. We disclose the interest so you can weigh it.

Trade names shown here (for example Matrixyl, Argireline, Syn-Ake) are the property of their respective owners and are used only to identify the ingredient under discussion. Their appearance implies no affiliation with, or endorsement by, the proprietor.

Evidence changes

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Cosmetic claims boundary
✓ Allowed (appearance / feel)
  • helps chemically lifted hair snap less under combing
  • improves slip and handling on bleached hair
  • leaves a more regular, better-imbricated cuticle surface
  • reinforces damaged fibre, session by session
✕ Not allowed (medicinal)
  • rebuilds disulfide bonds
  • repairs hair
  • permanent repair
  • restores hair to virgin condition
  • reverses damage

The medicinal-sounding science stays in the reference section; product copy speaks only to appearance/feel (Reg 655/2013). Different fields, never merged.

The honest part

The category name is doing work the evidence does not support. When the cortical claim was tested independently, disulfide content did not rise. What the molecule demonstrably does is interact with the fibre and leave a better-ordered surface, which is worth something on chemically lifted hair and is not what the premium is charged for.

Identity

Bis-Aminopropyl Diglycol Dimaleate is a small synthetic molecule: the dimaleate salt formed from maleic acid and the diamine derived from diethylene glycol and 1-aminopropane. Structurally it presents two maleate groups, which are α,β-unsaturated carbonyls and therefore capable of acting as Michael acceptors towards free thiol groups. It is used exclusively in hair formats, both in-salon during chemical services and in retail treatments, and it is the active that defined the bond-building category when that category did not previously exist.

Development & history

The molecule was developed in 2014 by Craig Hawker and Eric Pressly and commercialised as the basis of a bond-building hair range, with an extensive patent estate built around it. Its arrival created a new shelf category positioned explicitly against conditioning: not a surface treatment, the argument ran, but a structural one. The category has since expanded to dozens of brands and hundreds of products, with pricing justified by the chemistry claim rather than by measured consumer outcomes.

Independent structural investigation followed considerably later than the commercial success. The 2021 study by Di Foggia and colleagues at the University of Bologna was, by the authors' own account, the first application of vibrational spectroscopy to interrogate the proposed repairing mechanism directly.

Mechanism (as proposed)

The proposed mechanism is a sulfa-Michael addition. Bleaching oxidises cystine and leaves free thiol groups and oxidised sulfur species in the keratin. The maleate groups, as electrophilic Michael acceptors, are proposed to react with those thiols, and because the molecule is bifunctional it is proposed to bridge two keratin chains, generating a new covalent cross-link where a disulfide bridge was lost.

Two things should be held apart here. The chemistry is sound in principle: maleates are genuine Michael acceptors and keratin does present free thiols after bleaching. Whether that reaction occurs at meaningful scale inside the cortex of a hair fibre during a rinse-off treatment is a separate question, and it is the question the independent spectroscopic work addressed without finding the reaction.

Note also that any cross-link formed this way would be a thioether linkage, not a restored disulfide bridge. Even under the mechanism as proposed, the fibre is bridged rather than returned to its prior state.

Related reading

Our journal article on the bond-building category examines the claim, the independent evidence and the pricing in full. For the adjacent question of what does and does not act on hair at the follicle, see our coverage of hair growth actives and the complete hair loss guide.

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Sources — 2 cited
01Di Foggia M, Boga C, Micheletti G, Nocentini B, Taddei P. Structural investigation on damaged hair keratin treated with α,β-unsaturated Michael acceptors used as repairing agents. International Journal of Biological Macromolecules. 2021;167:620-632. PMID 33279560.
02United States Patent US 9,713,583 B2. Methods and formulations for curling hair. United States Patent and Trademark Office, 2017.
Updated 2026-08-28

Grades reflect the published evidence, not our interest. No dosing, reconstitution, or administration is published for research compounds — that restraint is deliberate.

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This site provides neutral scientific reference and sells only products lawful in your region. Nothing here is medical advice, a recommendation, or an offer to supply unapproved medicines. No dosing or administration is published for research compounds. Cosmetic peptides per Regulation (EC) 1223/2009. Unapproved injectable peptides are neither sold nor advertised in the EU (Directive 2001/83/EC, Title VIII). © 2026 Vallydia.