4-Benzoylphenyl Methacrylate: Properties, Synthesis & Applications

4-Benzoylphenyl Methacrylate is a bifunctional photoactive monomer combining a polymerizable methacrylate group with a benzophenone chromophore, enabling both free-radical copolymerization and subsequent UV-triggered crosslinking or surface-grafting reactions in polymer science research.

Chemical Name

4-Benzoylphenyl Methacrylate

CAS Number

To be confirmed (see review flag)

Molecular Formula

C₁₇H₁₄O₃

Molecular Weight

266.29 g/mol

Functional Groups

Methacrylate ester, benzophenone ketone

Key Application

UV-crosslinkable polymer coatings, photoresponsive hydrogels, surface functionalization

Source / Reference

TCI B6151

Chemical Identity and Structure

4-Benzoylphenyl Methacrylate (BPMA) is an ester formed by the reaction of 4-hydroxybenzophenone with methacryloyl chloride or methacrylic anhydride. Its structure integrates two chemically distinct and synthetically valuable moieties: a methacrylic ester that participates readily in free-radical, RAFT, ATRP, and other controlled polymerization techniques, and a benzophenone (diaryl ketone) unit that acts as a Type II photoinitiator chromophore upon UV irradiation.

The molecular formula is C₁₇H₁₄O₃ with a molecular weight of approximately 266.29 g/mol. The compound typically appears as a white to pale-yellow crystalline solid or powder. The benzophenone moiety absorbs UV light in the range of approximately 250–350 nm, generating a triplet excited state that abstracts hydrogen atoms from adjacent C–H bonds, leading to radical-mediated crosslinking or grafting without the need for a separate photoinitiator.

Synonyms: BPMA; 4-(Methacryloyloxy)benzophenone; Methacrylic acid 4-benzoylphenyl ester.

Photochemical Mechanism and UV Crosslinking

The benzophenone chromophore in BPMA is central to its utility as a photoactive comonomer. Upon absorption of UV light (typically 300–365 nm), benzophenone undergoes efficient intersystem crossing to the long-lived triplet excited state (T₁). This triplet species then abstracts a hydrogen atom from a proximal C–H donor—such as a polymer backbone, a C–H bond in a substrate surface, or a co-reagent—generating a carbon-centered radical pair. Radical recombination or addition leads to covalent crosslinks or graft bonds.

Because benzophenone functions as a self-contained photoinitiating unit within the polymer chain, polymers or copolymers bearing BPMA repeat units can be crosslinked or immobilized on hydrocarbon-rich surfaces simply by UV irradiation, without blending in small-molecule photoinitiators. This feature is especially advantageous for producing thin-film coatings, hydrogel networks, and biomaterial surfaces where extractable photoinitiator residues are undesirable.

Key photochemical parameters such as quantum yield and triplet lifetime are well-characterized for benzophenone chromophores in the literature, though specific values for BPMA-containing polymers depend on the copolymer composition and matrix; researchers are encouraged to consult primary literature for exact figures.

Applications in Polymer Science and Materials Research

BPMA is incorporated as a comonomer into a wide range of polymer architectures to confer photo-crosslinkability or surface-binding capability:

• UV-Crosslinkable Coatings and Films: Copolymers of BPMA with acrylates, methacrylates, or styrenic monomers can be deposited as thin films and subsequently crosslinked under UV light, improving mechanical integrity, chemical resistance, and adhesion.
• Photoresponsive Hydrogels: BPMA is copolymerized with hydrophilic monomers such as N-isopropylacrylamide (NIPAM), acrylamide, or poly(ethylene glycol) methacrylates to produce hydrogel networks whose crosslink density and swelling behavior can be tuned by UV exposure time and intensity.
• Surface Functionalization and Biomaterial Coatings: Polymers bearing pendant benzophenone groups can be photo-immobilized onto hydrocarbon-rich polymer substrates (polystyrene, polyethylene, PDMS) without surface pretreatment, enabling the creation of antifouling, cell-adhesive, or drug-releasing coatings for biomedical devices.
• Sensor and Diagnostic Platforms: BPMA-containing polymers have been used to photochemically attach biorecognition molecules (antibodies, oligonucleotides) to sensor surfaces, providing a versatile platform for biosensor fabrication.
• Controlled Radical Polymerization: BPMA is compatible with RAFT and ATRP protocols, allowing synthesis of well-defined block copolymers and nanostructures with precisely located photoactive segments.

Handling, Storage, and Safety Considerations

As with all reactive monomers, proper handling of 4-Benzoylphenyl Methacrylate is essential to ensure laboratory safety and maintain product quality.

Storage: BPMA should be stored in a cool, dry, well-ventilated area, protected from light and heat sources, in a tightly sealed container. As a monomer containing a polymerizable double bond, the compound is typically supplied with an inhibitor (such as hydroquinone or MEHQ) to prevent premature polymerization during storage. Recommended storage temperature is generally 2–8 °C or as specified on the product certificate of analysis. Always consult the current Safety Data Sheet (SDS) for confirmed storage conditions.

Handling: Use appropriate personal protective equipment (PPE) including nitrile gloves, safety glasses, and a laboratory coat. Work in a well-ventilated fume hood. Avoid prolonged skin contact, inhalation of dust, and exposure to ignition sources. The benzophenone moiety is a UV absorber; minimize unnecessary UV exposure of the neat compound during handling.

Waste Disposal: Dispose of waste material in accordance with local, regional, and national regulations for chemical waste. Do not dispose of via drain or general waste.

Note: Specific hazard classifications, GHS pictograms, and first-aid measures are compound- and jurisdiction-specific. Always refer to the current Aladdin Scientific SDS for authoritative safety information.

Ordering Information and Specifications

Aladdin Scientific offers 4-Benzoylphenyl Methacrylate (SKU: B405451) sourced with reference to TCI B6151 quality standards. Researchers and procurement teams should request the current Certificate of Analysis (CoA) for lot-specific purity data, including HPLC purity, inhibitor content, and spectroscopic identity confirmation (NMR, IR).

For bulk quantities, custom packaging, or technical support regarding polymerization protocols and formulation recommendations, please contact the Aladdin Scientific technical team directly.

Recommended complementary reagents: Free-radical initiators (e.g., AIBN, APS), RAFT agents, ATRP ligands and metal catalysts, hydrophilic comonomers (NIPAM, HEMA, PEGMA), crosslinker standards, and UV light sources (365 nm lamps, UV reactors).

Frequently asked questions

What makes 4-Benzoylphenyl Methacrylate different from other photoactive monomers?

BPMA uniquely combines a free-radically polymerizable methacrylate group with a benzophenone unit that acts as its own Type II photoinitiator upon UV exposure. Unlike monomers that require separate photoinitiator additives, BPMA-containing copolymers can be crosslinked or surface-grafted by UV irradiation without additional reagents, reducing potential extractable impurities in the final material.

Is 4-Benzoylphenyl Methacrylate compatible with RAFT and ATRP polymerization?

Yes, BPMA contains a standard methacrylate functionality and is generally compatible with both RAFT (reversible addition-fragmentation chain transfer) and ATRP (atom transfer radical polymerization) protocols, allowing the synthesis of well-defined block copolymers with controlled molecular weight and narrow dispersity. Researchers should optimize RAFT agent or catalyst selection for their specific comonomer system.

How should inhibitor be removed before polymerization of BPMA?

Standard inhibitor-removal techniques for methacrylate monomers apply to BPMA. These typically include passing the monomer through a column of activated basic alumina or inhibitor-removal resin, or by washing with dilute sodium hydroxide solution followed by drying over anhydrous magnesium sulfate and filtration, under subdued light to avoid premature photopolymerization. Always use freshly purified monomer for best polymerization control.

What UV wavelength is recommended for crosslinking BPMA-containing polymers?

Benzophenone chromophores in BPMA-containing polymers absorb broadly in the UV range, with effective crosslinking typically achieved using 300–365 nm UV sources. A 365 nm UV lamp (e.g., handheld UV lamp or UV conveyor system) is a common laboratory choice. The optimal irradiation time and intensity depend on film thickness, copolymer composition, and desired crosslink density, and should be optimized empirically for each specific application.

References

1. TCI Chemicals. Product Data Sheet: B6151, 4-Benzoylphenyl Methacrylate. Tokyo Chemical Industry Co., Ltd.
2. Fouassier, J.P.; Lalevée, J. Photoinitiators for Polymer Synthesis: Scope, Reactivity, and Efficiency. Wiley-VCH, 2012.
3. Dübner, M.; Spencer, N.D.; Padeste, C. Light-Responsive Polymer Surfaces via Postpolymerization Modification of Grafted Polymer-Brush Structures. Langmuir, 2014.

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