Dual-Reactive · pH-Responsive Copolymer
Poly(NHSMA-co-AA)
Also written P(NHSMA-co-AA), NHSMA-AA copolymer | Custom composition — no single CAS
A random copolymer of N-hydroxysuccinimide methacrylate (NHSMA) and acrylic acid (AA). Unlike pairing NHSMA with a passive antifouling or hydrogel monomer, this combination gives the chain two genuinely different reactive handles: NHSMA units are pre-activated NHS esters, ready to couple with a primary amine immediately, while AA units are free, pH-responsive carboxylic acids that stay latent until you choose to activate them (e.g. with EDC/NHS) for a second round of conjugation.
- Moisture-sensitive — shipped and stored desiccated
Custom composition
(C₈H₉NO₄)ₘ-co-(C₃H₄O₂)ₙ
Poly(NHSMA-co-AA)
Appearance: White to off-white powder
Character: Dual-reactive, pH-responsive
Architecture: Random copolymer
Storage: −20 °C, desiccated, dark
ISO 9001:2015
Manufactured under certified quality management
Custom NHSMA:AA Ratio
Immediate vs. latent reactive-site density tuned independently
Batch-Level COA
Spectral data and free-dye content per lot
Desiccated Cold-Chain Packaging
Preserves NHS-ester reactivity in transit and storage
CAS No.
Composition-dependent
Molecular Formula
(C₈H₉NO₄)ₘ-co-(C₃H₄O₂)ₙ
Character
Dual-reactive, pH-responsive
Mn Range
8K – 100K
Form
Powder
One handle ready now, one ready when you are
NHSMA and AA aren't a "reactive plus passive" pair like our other NHSMA copolymers — both units are chemically reactive, just on different timelines.
NHSMA: pre-activated, react now
Each NHS ester is already an active ester — add a primary amine and it couples immediately, no activation reagent required.
AA: latent, activate when ready
The free carboxylic acid does nothing to amines on its own — it stays inert until you deliberately activate it (e.g. with EDC/NHS) for a second coupling.
Sequential, orthogonal conjugation
React the NHS sites with ligand #1 first, then separately activate and couple the AA sites with ligand #2 — two attachment chemistries on one chain.
AA also just... responds to pH
Even without activating it, the carboxylic acid still ionizes above its pKa (~4.5), giving the whole chain pH-responsive charge and solubility behavior.
The NHSMA:AA ratio sets how many sites are ready for immediate coupling versus how many stay as free, pH-responsive, activatable carboxylic acid — both counts matter independently for a dual-conjugation design.
Values below are representative for this monomer pair. Batch-specific COAs with GPC, composition, and NHS-ester activity data are available on request.
| Chemical Name | Poly(N-hydroxysuccinimide methacrylate-co-acrylic acid) |
|---|---|
| Synonyms | P(NHSMA-co-AA) · NHSMA-AA copolymer · Dual-reactive pH-responsive copolymer |
| Monomer Units | N-hydroxysuccinimide methacrylate (NHSMA) · acrylic acid (AA) |
| Architecture | Random (statistical) copolymer — not block or graft |
| NHSMA : AA Ratio | Custom / composition-dependent — commonly 2:98 to 30:70 mol% |
| Reactive Groups | NHS active ester (immediate, amine-reactive) · free carboxylic acid (latent, pH-responsive, EDC-activatable) |
| CAS Number | Not applicable — composition-specific random copolymers are not assigned a single CAS RN |
| Molecular Weight (Mn) | Custom synthesis, typically 8,000–100,000 g/mol |
| Dispersity (Đ) | 1.1–1.3 (RAFT/ATRP) · broader for free-radical routes |
| Appearance | White to off-white powder |
| Solubility | DMF, DMSO, and dry organic solvents for NHS coupling; water-soluble away from the acid’s isoelectric behavior |
| Reactivity Note | NHS ester is hydrolytically unstable in water — dissolve and react promptly; avoid primary-amine buffers |
| Storage | Sealed, desiccated, −20 °C, protected from light and moisture |
Choose the balance of immediate vs. latent sites
NHSMA:AA feed ratio sets how many sites are ready for coupling right away versus how many stay as free, activatable carboxylic acid.
NHSMA : AA ≈ 2:98
AA-dominant
Behaves close to a standard pH-responsive polyacrylic acid, with just a few pre-activated sites for sparse, single-ligand conjugation.
NHSMA : AA ≈ 10:90
Balanced
A practical working range for dual-conjugation designs — meaningful immediate coupling density alongside a large latent-acid reserve.
NHSMA : AA ≈ 30:70
Reactive-rich
Applications
pH-responsive drug delivery with a handle
AA gives pH-triggered swelling/release behavior; the pre-installed NHS sites carry the drug, targeting ligand, or imaging tag.
Sequential dual-ligand conjugation
Attach one biomolecule via the NHS sites, then a second via EDC-activated AA sites — two chemistries, one chain.
Metal-chelating reactive polymers
Free carboxylate groups chelate metal ions while NHS sites separately attach a targeting or reporter molecule.
LbL coatings with post-assembly function
AA's anionic character supports electrostatic layer-by-layer assembly; the surviving NHS sites are functionalized after the film is built.
Multivalent nanoparticle coatings
Two independent conjugation chemistries on one coating polymer allow separate control over targeting and stability/reporter functions.
Functional flocculants
Free acid groups drive standard charge-based flocculation while NHS sites optionally tag the polymer for tracking or further modification.
Biosensor surfaces (dual anchoring)
Ionic anchoring through AA groups plus covalent, oriented capture-molecule attachment through NHS sites on the same interface.
pH-responsive PPM libraries
One precursor batch, split and coupled to different amines via the NHS sites, still retains a shared pH-responsive AA backbone.
Data & safety documents
Batch-specific COAs with GPC, composition (¹H-NMR), and NHS-ester activity data available for order confirmations. Contact us for a specific lot number.
Safety Data Sheet
GHS-format · EN / ZH
Certificate of Analysis
Ratio + Mw confirmation
Sequential Coupling Protocol
NHS step, then EDC/NHS activation step
FAQ
Most frequent questions and answers
It’s used wherever a design calls for two independent conjugation chemistries on one polymer chain, or for a pH-responsive acid backbone that also carries a small number of ready-to-use reactive sites — sequential dual-ligand bioconjugation, multivalent nanoparticle coatings, metal-chelating reactive polymers, and pH-responsive drug delivery with a built-in attachment handle.
NHSMA units carry a pre-activated NHS ester that reacts with a primary amine immediately, no activation step needed. AA units carry a free carboxylic acid that is unreactive toward amines on its own — it stays as a latent, pH-responsive group until you deliberately activate it (typically with EDC/NHS) for a separate coupling reaction.
Yes — that’s the main reason to choose this pairing. Because the two reactive groups work on different timelines (NHS immediate, AA latent), you can react the NHS sites with one amine-bearing molecule first, then separately activate the AA sites and couple a second molecule, giving sequential, orthogonal dual conjugation on a single chain.
No. Free carboxylic acids don’t react with NHS esters under normal coupling conditions, so the AA units are inert bystanders during the first (NHS/amine) coupling step. They only become reactive once you deliberately add an activating reagent like EDC.
Yes. Independent of whether the NHS sites have been reacted, the AA units still ionize above their pKa (~4.5), giving the whole chain standard weak-polyacid behavior — increased charge, hydration, and solubility at higher pH, and reduced charge and solubility at low pH.
A typical workflow: (1) dissolve the polymer fresh and react the NHS sites with your first amine-bearing molecule under standard NHS-coupling conditions; (2) purify the intermediate; (3) activate the remaining free carboxylic acids with EDC (optionally plus fresh NHS) and couple a second amine-bearing molecule. Running the steps in this order avoids cross-reactivity between the two chemistries.
No — composition-specific random copolymers like this one are not assigned a single CAS Registry Number, since the NHSMA:AA ratio, Mn, and dispersity are set per synthesis batch. Each lot’s COA documents the actual composition and NHS-ester activity.
Store sealed, desiccated, at −20 °C, protected from light and moisture — the NHS ester is sensitive to both heat and humidity. The AA units are comparatively stable, but for best results still dissolve the polymer fresh and complete the NHS coupling step promptly before moving on to any EDC activation step.