Tougher Coatings, Smarter Chemistry with Photomer® 6648

How iGM Resins' latest study reveals the impact of multifunctional monomers on urethane acrylate performance

At RadTech UV+EB 2025, Liz Mendez presented new findings on how to enhance mechanical properties in UV-curable urethane acrylates using multifunctional monomers. The study, conducted by Brian Dillman in our Applications Lab in Charlotte, US, attracted strong interest from formulators seeking both performance and flexibility in next-generation coatings.

Meeting Evolving Demands
Today’s industrial and graphic coatings must endure more: abrasion, impacts, and harsh environments, while remaining compliant and easy to apply. Toughness and flexibility are no longer opposing choices; they are expected together.

Our Technical Approach
Using Photomer® 6648, a soft, tetra-functional aliphatic urethane acrylate, as the oligomer base, we tested blends with di-, tri-, and tetra-functional acrylate monomers. Each formulation was UV-cured and evaluated for tensile strength, elongation, viscosity, and cure-induced shrinkage. Dynamic Mechanical Analysis (DMA) and tensile testing provided critical insight into crosslink density and thermal-mechanical behavior.

About Photomer® 6648:

• Tensile Modulus: 67 MPa
• Elongation: 16 %
• Tensile Strength: 9 MPa
• Tg (tan δ max): 8 °C
• 24-hr Water Absorption: 2.7%

Learn more about Photomer® 6648 and download the PDS and SDS. 

Key Takeaways

• Photomer® 6648 offers excellent compatibility, flexibility, and relatively low viscosity. It’s a versatile base resin for many formulations.
• Tri- and tetra-functional monomers increase stiffness (modulus), while reducing elongation, which highlights a clear trade-off in performance.
• Shrinkage behavior correlated with monomer structure, confirming the importance of careful monomer selection for dimensional control.
• Photomer® 4226 (DPGDA) delivered unexpectedly high performance, outperforming other diacrylates and even some triacrylates in modulus-to-crosslink trends.

What This Means for You
By adjusting the type and ratio of acrylate monomers, formulators can tailor UV-curable systems to meet specific performance needs, depending on whether toughness, flexibility, or cure stability is the priority.

Let’s Collaborate
Looking to boost the performance of your UV formulations? Contact our technical experts to discuss how Photomer® and our multifunctional monomers can bring your next innovation to life.