Dual pH & Thermoresponsive Copolymer
Poly(4VP-co-NIPAM)
Also known as P(4VP-co-NIPAM), 4VP-NIPAM copolymer | Custom composition — no single CAS
A random copolymer of 4-vinylpyridine (4VP) and N-isopropylacrylamide (NIPAM) on one backbone. NIPAM units bring PNIPAM’s classic thermoresponsive lower critical solution temperature (LCST, ~32 °C for the homopolymer); 4VP units bring a pH-switchable charge that shifts how hydrophilic the chain is at a given temperature — so pH doesn’t just add a second trigger, it moves where the thermal transition happens.
- Custom 4VP:NIPAM ratio, multiple Mw grades
Custom composition
(C₇H₇N)ₘ-co-(C₆H₁₁NO)ₙ
Poly(4VP-co-NIPAM)
Appearance: White to off-white powder
Character: pH-tunable thermoresponsive
Architecture: Random copolymer
Storage: 2–8 °C, sealed, dry
ISO 9001:2015
Manufactured under certified quality management
Custom 4VP:NIPAM Ratio
Synthesized to order, sets where the cloud point falls
Batch-Level COA
Mn, Đ, and cloud-point confirmation per lot
Sample to Bulk
Gram-scale R&D up to bulk supply
CAS No.
Composition-dependent
Molecular Formula
(C₇H₇N)ₘ-co-(C₆H₁₁NO)ₙ
Character
pH-tunable thermoresponsive
Mn Range
10K – 150K
Form
Powder
A thermal switch that moves with pH
NIPAM sets the baseline thermoresponsive behavior; 4VP layers a pH handle on top that shifts where that thermal transition sits.
NIPAM: thermoresponsive LCST
Pure PNIPAM undergoes a coil-to-globule collapse and phase-separates from water above ~32 °C — its lower critical solution temperature.
4VP: pH-tunable hydrophilicity
Protonated (low pH) pyridine units are hydrophilic and resist collapse, raising or suppressing the transition; neutral (high pH) units behave more like a passive comonomer.
Ratio sets the transition window
Higher NIPAM content keeps the cloud point close to 32 °C; higher 4VP content broadens or pushes the transition to a higher, more pH-sensitive range.
Quaternizable handle
The pyridine N can be alkylated post-polymerization, locking in permanent cationic charge and further shifting the thermal response.
The marker shows the approximate direction of the shift, not a fixed temperature — actual cloud point depends on the 4VP:NIPAM ratio, ionic strength, and heating rate, and should be measured (e.g. by turbidimetry) for a specific batch.
Values below are representative for this monomer pair. Batch-specific COAs with GPC and cloud-point data are available on request.
| Chemical Name | Poly(4-vinylpyridine-co-N-isopropylacrylamide) |
|---|---|
| Synonyms | P(4VP-co-NIPAM) · 4VP-NIPAM copolymer · Poly(4VP-r-NIPAM) · Dual pH/thermoresponsive copolymer |
| Monomer Units | 4-vinylpyridine (4VP) · N-isopropylacrylamide (NIPAM) |
| Architecture | Random (statistical) copolymer — not block or graft |
| 4VP : NIPAM Ratio | Custom / composition-dependent — commonly 5:95 to 40:60 mol% |
| Cloud Point / LCST | Batch- and pH-dependent, typically 30–45 °C (pure PNIPAM reference: ~32 °C) |
| 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 | Cold water, below cloud point; acidic aqueous media extends solubility to higher temperatures |
| Key Functional Groups | Pyridine (basic, quaternizable) · secondary amide (thermoresponsive, H-bonding) |
| Storage | Sealed, dry, 2–8 °C, protected from light |
Need a specific cloud point or 4VP:NIPAM ratio? Talk to technical sales →
Choose the ratio that fits your transition target
4VP:NIPAM feed ratio sets how close the cloud point stays to PNIPAM's ~32 °C baseline and how strongly it shifts with pH.
4VP : NIPAM ≈ 5:95
NIPAM-dominant
Cloud point stays close to the ~32 °C PNIPAM baseline, with only a mild pH sensitivity — closest to a “pure thermoresponsive” grade.
4VP : NIPAM ≈ 20:80
Balanced
Clear, practically useful pH-shift of the cloud point while retaining a sharp, well-defined thermal transition.
4VP : NIPAM ≈ 40:60
4VP-rich
Strongest pH tunability and the most available pyridine N for quaternization; transition broadens and may be suppressed at low pH.
Applications
Dual-triggered drug delivery
Combined temperature and pH triggers — e.g. mild hyperthermia plus a slightly acidic tumor microenvironment — drive targeted cargo release.
Thermally switchable coatings
Surfaces that reversibly change wettability or fouling resistance as temperature crosses the copolymer's cloud point.
Soft actuators
Reversible swelling/collapse driven by temperature (and tuned by pH) converts a stimulus into mechanical motion in hydrogel actuators.
Temperature-responsive chromatography
Analyte retention on a grafted stationary phase can be tuned by both column temperature and mobile-phase pH.
Layer-by-layer & smart films
Protonated pyridine units support electrostatic assembly, while the NIPAM component adds a reversible thermal switch to the film.
Dual-responsive microgels
Crosslinked particles undergo a combined volume phase transition that can be triggered independently or jointly by heat and pH.
Dual-signal biosensors
A measurable optical or electrochemical change on crossing the cloud point can be gated by sample pH for added selectivity.
Thermally reversible flocculants
Heating past the cloud point collapses and aggregates the chains, enabling temperature-triggered separation in water treatment.
Data & safety documents
Batch-specific COAs with GPC, composition (¹H-NMR), and cloud-point (turbidimetry) 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
¹H-NMR Spectrum
Structure confirmation
FAQ
Most frequent questions and answers
It’s used wherever a stimuli-responsive material needs two independent triggers instead of one — dual-triggered drug delivery, thermally switchable coatings, soft actuators, temperature-responsive chromatography, and dual-responsive microgels — because the cloud point can be moved with pH in addition to the usual thermal switch.
NIPAM units are responsible for the classic thermoresponsive behavior — a sharp coil-to-globule collapse above a critical temperature. 4VP units are a weak base whose protonation state changes with pH; when protonated they’re hydrophilic and resist that collapse, which is what lets pH shift the thermal transition.
Pure PNIPAM has an LCST of about 32 °C in water. Copolymerizing with 4VP shifts and broadens this cloud point, and — because 4VP is pH-responsive — the transition temperature itself changes with solution pH, typically rising (or being suppressed) as pH drops and the pyridine units protonate.
No. Pure PNIPAM homopolymer has a fixed, pH-insensitive LCST around 32 °C. This copolymer starts from that same thermoresponsive backbone but adds a genuinely pH-tunable transition point via the 4VP units — a feature pure PNIPAM doesn’t have on its own.
Because it’s a random copolymer, the ratio is set at synthesis and is usually made to order. Common research compositions range from NIPAM-dominant (~5:95) for a near-pure thermoresponsive profile, to 4VP-rich (~40:60) for strong pH tunability.
No — composition-specific random copolymers like this one are not assigned a single CAS Registry Number, since the 4VP:NIPAM ratio, Mn, and dispersity are set per synthesis batch. Each lot’s COA documents the actual composition and measured cloud point.
Store sealed, dry, at 2–8 °C, protected from light. The thermal transition itself is reversible on cooling back below the cloud point, but repeated heating/cooling cycles and prolonged storage above the transition temperature can promote aggregation, so dissolve fresh solutions below the cloud point when possible.