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Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction
Published on: January 19, 2016
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Dynamic mechanical analysis of high pressure polymerized urethane dimethacrylate
Pascal Béhin1, Grégory Stoclet2, N Dorin Ruse3
1Laboratoire de biomatériaux dentaires, Faculté de chirurgie dentaire, Université de Lille 2, Lille, France.
Summary
High pressure polymerization of urethane dimethacrylate (UDMA) enhances crosslink density and viscoelastic properties. However, higher temperatures or lack of initiator negatively impacts these properties, as confirmed by dynamic mechanical analysis and atomic force microscopy.
Area of Science:
- Polymer Science
- Materials Science
- Biomaterials Engineering
Background:
- Urethane dimethacrylate (UDMA) is a key component in dental composites and other polymer applications.
- Understanding the viscoelastic properties of UDMA is crucial for optimizing material performance.
- Current polymerization methods may not fully exploit UDMA's potential crosslinking capabilities.
Purpose of the Study:
- To compare the viscoelastic properties of high pressure (HP) polymerized UDMA with conventional methods.
- To investigate the influence of polymerization parameters (protocol, temperature, initiator) on HP-polymerized UDMA.
- To correlate viscoelastic properties with polymer network morphology.
Main Methods:
- Dynamic Mechanical Analysis (DMA) in three-point bending to determine viscoelastic properties (Tg, E', E", E'rub, tanδ).
- Atomic Force Microscopy (AFM) to characterize fractured polymer surface morphologies.
- Comparison of polymers polymerized under high pressure (HP) versus ambient pressure (thermo- and photo-polymerized).
Main Results:
- HP-polymerization significantly increased glass transition temperature (Tg) and rubbery storage modulus (E'rub), indicating higher crosslink density.
- Modifying the polymerization protocol increased tanδ, while higher polymerization temperatures decreased E'rub and Tg.
- Absence of initiator resulted in the lowest mechanical properties and highest tanδ, suggesting significantly reduced crosslink density.
- AFM revealed distinct surface morphologies between HP-polymerized and control UDMA materials.
Conclusions:
- Polymerization under high pressure (HP) effectively increases the crosslink density and enhances the viscoelastic properties of UDMA.
- Higher polymerization temperatures and the absence of an initiator are detrimental to the desired viscoelastic properties of HP-polymerized UDMA.
- AFM confirmed changes in polymer network morphology corresponding to variations in polymerization conditions.
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