pH-Responsive · Hydrogel-Forming Copolymer
Poly(4VP-co-HEMA)
Also known as P(4VP-co-HEMA), 4VP-HEMA copolymer | Custom composition — no single CAS
A random copolymer of 4-vinylpyridine (4VP) and 2-hydroxyethyl methacrylate (HEMA) on one backbone. HEMA is the workhorse monomer behind soft contact lenses and biomedical hydrogels — hydrophilic, biocompatible, and hydrogel-forming on its own. 4VP layers a pH-responsive, quaternizable, metal-coordinating pyridine handle onto that matrix, which is why this pairing shows up constantly as the functional monomer in molecularly imprinted polymers (MIPs) and pH-triggered hydrogel devices.
- Custom 4VP:HEMA ratio, multiple Mw grades
Custom composition
(C₇H₇N)ₘ-co-(C₆H₁₀O₃)ₙ
Poly(4VP-co-HEMA)
Appearance: White to off-white powder
Character: pH-responsive + hydrogel-forming
Architecture: Random copolymer
Storage: 2–8 °C, sealed, dry
ISO 9001:2015
Manufactured under certified quality management
Custom 4VP:HEMA Ratio
Synthesized to order, sets recognition density and swelling
Batch-Level COA
Mn, Đ, and composition confirmation per lot
Sample to Bulk
Gram-scale R&D up to bulk supply
CAS No.
Composition-dependent
Molecular Formula
(C₇H₇N)ₘ-co-(C₆H₁₀O₃)ₙ
Character
pH-responsive + hydrogel-forming
Mn Range
10K – 150K
Form
Powder
A hydrogel matrix with a built-in recognition handle
HEMA supplies the bulk hydration and biocompatibility that make a hydrogel; 4VP supplies a specific, pH-switchable functional group inside that matrix.
HEMA: hydrophilic hydrogel backbone
The pendant hydroxyl group hydrates strongly and is biocompatible enough for contact lenses on its own — it forms the swollen, water-retentive matrix.
4VP: pH-responsive recognition site
The pyridine N protonates below its apparent pKa, adding charge-driven swelling and a metal-/analyte-coordinating site that HEMA alone doesn't provide.
Ratio sets swelling and recognition density
A HEMA-rich feed favors a stable, near-neutral hydrogel matrix; a 4VP-rich feed favors stronger pH-driven swelling and more recognition/binding sites.
Quaternizable handle
The pyridine N can be alkylated post-polymerization for permanent cationic charge — useful for antimicrobial or ion-exchange hydrogel variants.
Above the pyridine's apparent pKa (~4–5), swelling is governed mostly by HEMA's constant hydration. Below it, protonation adds electrostatic repulsion and osmotic pressure inside the network, increasing water uptake — the classic pH-triggered swelling curve used in controlled-release hydrogels.
Values below are representative for this monomer pair. Batch-specific COAs with GPC and composition data are available on request.
Chemical Name | Poly(4-vinylpyridine-co-2-hydroxyethyl methacrylate) |
|---|---|
| Synonyms | P(4VP-co-HEMA) · 4VP-HEMA copolymer · Poly(4VP-r-HEMA) · pH-responsive hydrogel copolymer |
| Monomer Units | 4-vinylpyridine (4VP) · 2-hydroxyethyl methacrylate (HEMA) |
| Architecture | Random (statistical) copolymer — not block or graft |
| 4VP : HEMA Ratio | Custom / composition-dependent — commonly 5:95 to 50:50 mol% |
| CAS Number | Not applicable — composition-specific random copolymers are not assigned a single CAS RN |
| Molecular Weight (Mn) | Custom synthesis, typically 10,000–150,000 g/mol |
| Dispersity (Đ) | 1.1–1.3 (RAFT/ATRP) · broader for free-radical routes |
| Appearance | White to off-white powder |
| Solubility | Water and lower alcohols (composition-dependent); swells rather than dissolves once crosslinked |
| Key Functional Groups | Pyridine (basic, quaternizable, metal-coordinating) · pendant hydroxyl (hydrating, H-bonding) |
| Storage | Sealed, dry, 2–8 °C, protected from light |
Need a specific 4VP:HEMA ratio, or a pre-crosslinked hydrogel/MIP formulation? Talk to technical sales →
Choose the ratio that fits your matrix
4VP:HEMA feed ratio sets the balance between a stable hydrogel matrix and pH-driven, recognition-active swelling.
4VP : HEMA ≈ 5:95
HEMA-dominant
Behaves close to a standard HEMA hydrogel matrix, with a light pyridine functionality for mild recognition or coordination.
4VP : HEMA ≈ 20:80
Balanced
A common starting point for MIP functional-monomer work — meaningful recognition density without losing hydrogel stability.
4VP : HEMA ≈ 50:50
4VP-rich
Strong pH-responsiveness and high pyridine density for maximum recognition/chelation capacity or quaternization.
Applications
Molecularly imprinted polymers
4VP is one of the most widely used functional monomers in MIP synthesis; HEMA provides a hydrophilic, biocompatible matrix around the recognition sites.
Contact lens & ocular hydrogels
Builds on HEMA's proven ophthalmic biocompatibility while adding pH-responsive drug loading and release.
pH-triggered drug delivery
Swelling that increases at low pH gives a straightforward, tunable release mechanism for oral and topical hydrogel carriers.
Wound-dressing hydrogels
Moisture-retentive HEMA matrix with an optional quaternized-pyridine antimicrobial function built into the same network.
Metal ion chelating hydrogels
Pyridine N coordinates transition-metal ions within a swollen, permeable HEMA network — useful for adsorption and sequestration.
Dental adhesives & composites
HEMA is a standard dental-material monomer; added pyridine functionality supports further modification or ion binding.
Biosensor hydrogel matrices
A hydrated, permeable HEMA scaffold with pyridine binding sites supports analyte capture near an embedded transducer.
Superabsorbent / swelling actuators
Charge-driven osmotic swelling at low pH can be harnessed for pH-triggered actuation or absorption devices.
Data & safety documents
Batch-specific COAs with GPC and composition (¹H-NMR) 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
Swelling Ratio vs. pH
Equilibrium water uptake data
FAQ
Most frequent questions and answers
It’s used wherever you need a hydrophilic, biocompatible hydrogel matrix with a built-in functional recognition or pH-responsive site — most commonly as the functional monomer/matrix pair in molecularly imprinted polymers (MIPs), pH-responsive drug-delivery hydrogels, contact-lens materials, and wound dressings.
HEMA units are non-ionic and hydrophilic through their hydroxyl group — they hydrate the network and are responsible for its biocompatibility and baseline swelling. 4VP units are a weak base whose pyridine N protonates at low pH, adding charge-driven swelling, metal-coordination ability, and a site for post-polymerization modification that HEMA doesn’t provide.
Yes — 4-vinylpyridine is one of the most common functional monomers in MIP synthesis because its pyridine N hydrogen-bonds and coordinates with many template molecules, while HEMA (or similar hydrophilic comonomers) helps keep the resulting imprinted network compatible with aqueous sample matrices.
The linear copolymer as supplied is water-soluble or water-swellable rather than a fixed hydrogel. To make an insoluble, swelling hydrogel network (as used in contact lenses, MIPs, or wound dressings), it’s typically copolymerized or post-crosslinked with a difunctional agent such as ethylene glycol dimethacrylate (EGDMA).
HEMA itself has a long track record in ophthalmic and biomedical hydrogels, so HEMA-rich compositions are generally well tolerated as a starting material. Full biocompatibility still depends on final composition, crosslinker, residual monomer levels, and processing, and should be confirmed for your specific device and regulatory pathway.
Yes. The 4VP pyridine nitrogen can be alkylated post-polymerization to add permanent cationic charge — a common way to introduce antimicrobial or ion-exchange character into an otherwise standard HEMA hydrogel.
No — composition-specific random copolymers like this one are not assigned a single CAS Registry Number, since the 4VP:HEMA ratio, Mn, and dispersity are set per synthesis batch. Each lot’s COA documents the actual composition.
Store sealed, dry, at 2–8 °C, and protected from light. The uncrosslinked copolymer generally dissolves well in water or dilute acid; once crosslinked into a hydrogel, it swells rather than dissolves, with the degree of swelling depending on pH as described above.