Structure–property relationships in photopolymerizable polymer networks: Effect of composition on the crosslinked structure and resulting thermomechanical properties of a (meth)acrylate‐based system

Abstract

Photoinitiated polymer networks were formed by copolymerization of tert-butyl acrylate with di(ethylene glycol) dimethacrylate (DEGDMA) or poly(ethylene glycol) dimethacrylate (PEGDMA). The degree of crosslinking was systematically varied by modifying the weight fraction and molecular weight of the dimethacrylate crosslinking agent. An increase in effective crosslink density with increasing crosslinking agent concentrations was confirmed by decreasing equilibrium swelling ratios (q) and increasing rubbery moduli (E R ). Glass transition temperatures (T g ) varied from À22 to 1248C, increasing with increasing DEGDMA content and decreasing with increasing PEGDMA content. Tensile deformation behavior (at T g ) ranged from an elastomeric-like large-strain response for lightly crosslinked materials to a small-strain brittle response for highly crosslinked networks. At low crosslinking levels, the strain-to-failure of the network polymers decreased quickly with increasing crosslinking agent concentration. The stress at failure demonstrated a more complex relationship with crosslinking agent concentration. The effect of composition on network structure and resulting properties (q, E R , strain-to-failure) decreased as the crosslinking agent concentration increased. The results reveal trade-offs in T g , E R , strain-to-failure, and failure stress with composition and network structure, and are discussed in light of the wide range of potential applications suggested in the literature for (meth)acrylate-based photopolymerizable polymer networks including biomaterials and shape-memory polymers.

The effect of organoclay addition on the properties of an acrylate based, thermally activated shape memory polymer

“…The rubbery storage modulus increased as the PEGDMA content increased in line with work with related systems (Gall et al, 2005;Kramer et al, 2010;Ortega et al, 2008).…”

“…Previous investigations by Ortega et al (2008), Yakacki et al (2008) and Yang et al (2007) have shown that tert-butylacrylate-co-poly(ethylene glycol) dimethacrylate (tBA-co-PEGDMA) networks have shape memory ability with thermal and mechanical properties that can be readily tailored. In this particular example a transition temperature near 40°C was required.…”

High catalytic efficiency of palladium nanoparticles immobilized in a polymer membrane containing poly(ionic liquid) in Suzuki–Miyaura cross-coupling reaction

“…The cross-linker b is used to prevent the dissolution of the poly(ionic liquid) by the organic solvent during the reaction. The length and molecular weight of the cross-linking monomer were appropriately adapted to favor the formation of a homogeneous network [25][26][27][28]. The presence of the methyl group at C2 position on the imidazolium ring avoids the formation of molecular palladium N-heterocyclic carbene complexes under basic conditions [29], which could eventually promote palladium leaching from the membrane.…”

High‐Strain Shape‐Memory Polymers

“…When copolymerizing different acrylate monomers, small compositional changes have a large effect on mechanical properties, including elastic modulus, strain-to-failure, T g , brittleness at ambient temperatures, and percentage deformation in the rubbery regime. [26,27] Copolymerizing linear acrylates (monofunctional monomers) with crosslinking acrylates (multifunctional monomers) yields SMPs with tunable properties that can be optimized for very specific applications. Single-component methyl methacrylate (MMA) polymers [28] and random AB MMA copolymers [29] have been examined.…”