Tough, Transparent, Photocurable Hybrid Elastomers

Abstract

We investigated polydimethylsiloxane/poly(methyl methacrylate) (PDMS/PMMA) interpenetrating polymer networks (IPNs) by both sequential and simultaneous syntheses. In the sequential IPN, the PDMS network was first thermally cured after which methyl methacrylate was swelled in and UV photopolymerized in situ. The simultaneous IPN consists of a one-pot, single-step UV cure of both components. Pure shear fracture and tensile tests were used to extract the Young's modulus, critical fracture strain, and fracture energy of the materials at varying PMMA fractions (up to 50 wt %). At high PMMA fractions, a maximum increase in Young's modulus (42×) and fracture energy (21×) was observed with little sacrifice in the optical properties and the extensibility of notched samples. The Krieger−Dougherty model for particle reinforcement was fit to the modulus data as a function of the PMMA fraction and showed good agreement. The optical properties and microstructure of the IPNs were investigated by UV−visible light transmission, smallangle X-ray scattering (SAXS), and atomic force microscopy (AFM). As the weight fraction of PMMA increased, the simultaneous IPN became less transparent, while the sequential material showed the opposite trend. In the sequential IPN, the minority phase size decreased with increasing PMMA fraction, while it was constant for the simultaneous IPN. Therefore, it was concluded that the sequential IPN transparency is controlled by the size of the PMMA domains, but the simultaneous IPN transparency is controlled by the PMMA fraction. SAXS and AFM also showed evidence of bicontinuous network formation in the simultaneous IPN, which may affect the optical and mechanical properties.

Adaptable Reversibly Interlocked Networks from Immiscible Polymers Enhanced by Hierarchy-Induced Multilevel Energy Consumption Mechanisms

“…Thanks to the hierarchical structure, both the strengthening efficiency and the toughening efficiency of ILN-202 are simultaneously increased, which forms a contrast to other multicomponent polymer systems containing ionic interactions (Figure S14). Meanwhile, in comparison with (i) the single-component dual-cross-linked elastomers containing covalent cross-links and ionic interactions ,− and (ii) two-component co-networks (including double networks ,,,, and IPNs ,− ,− ), our interlocked networks possess the highest tensile strength, and the failure strain is also superior to most systems (Table S5). It is worth noting that many two-component co-networks ,− are based on miscible couples, but their mechanical properties are lower than those of interlocked networks made from immiscible polymers.…”

Silicone‐based polymer blends: Enhancing properties through compatibilization

“…Although sequential strategies provide well‐disperse IPNs with unique morphologies, they are often not very practical for industrial applications. An interesting alternative to the sequential approach is IPN formation via simultaneous polymerization processes 82 . In these systems, the morphology depends on homopolymer incompatibility and the polymerization conditions, including mixing and the kinetics of each reaction 16 .…”

High-Throughput Screening Test for Adhesion in Soft Materials Using Centrifugation

“…To cast a bottom layer in each well of the multiwell plate, we adapted the formulation and the procedure from Rapp et al We chose poly­(methyl methacrylate) (PMMA) as it is fast curing and is glassy at room temperature. , We made a prepolymer of PMMA by dissolving PMMA (purchased from Sigma-Aldrich, average MW ∼15 000 g/mol by GPC) in methyl methacrylate (Fisher Chemical) at a 1:2 mass ratio. In an amber vial, we added 2-hydroxy-2-methylpropiophenone as the initiator (5%), ethylene glycol dimethacrylate as the cross-linker (5%), and prepolymer (90%), and we sparged the solution with nitrogen for 1 h. We then pipetted 30 μL of the mixed solution into each well of a 384-well plate composed of polyproylene (384PP 2.0, Labcyte).…”