Mechanical and Thermomechanical Characterization of Glassy Thermoplastics with Intrachain Cross-Links

Abstract

The mechanical properties of an amorphous polymer are a consequence of the inter- and intramolecular interactions which are typically similar. Yet, polymers can be made with covalent intramolecular cross-links, leading to stronger intramolecular interactions. Here, a study on the effect of this intramolecular cross-linking on the mechanical properties of a glassy polymer is shown. A linear poly­(methyl methacrylate) with defined size was cross-linked at different ratios and assembled into solid samples by solvent casting. Mechanical testing indicates that intramolecular cross-linking does not affect the mechanical properties at the elastic region but does influence these properties at the plastic region. Interestingly, intramolecular cross-linking leads to different effects than “regular” interchain cross-linking. The results are consistent with a reduction in chain entanglement, reducing toughness and to a lesser extent strength.

Highly Stretchable Polymers: Mechanical Properties Improvement by Balancing Intra‐ and Intermolecular Interactions

“…The glass transition temperature was measured using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) to provide some experimental indications on the effect of intramolecular CL on segmental dynamics. In agreement with ours and others previous results, T g increases in PBMA with increasing CL degree (Table ). T g 's determined by MD simulations found the same trend ( Table 2 ).…”

“…Many studies have characterized SCPN molecular level behavior in solution, in addition to a few melt studies which looked at the interactions between the folded chains . Finally, more recently, we have conducted experimental and theoretical studies to better understand the influence of intramolecular CLs in the solid state, looking at mechanical and thermomechanical behavior of SCPNs assembled into bulk thermoplastic materials . Our initial studies focused on the effects of intramolecular CLs below the glass transition temperature ( Tg ) such as reducing chain entanglement and decreasing ductility.…”

Effect of intramolecular crosslinker properties on the mechanochemical fragmentation of covalently folded polymers

“…As in our recent studies, 9,23 the chemistry chosen for intramolecular folding is grounded on the Michael addition of poly(MMA) [(PMMA)-co-AEMA], 24 since it offers a simple and reliable crosslinking chemistry which can be easily followed by NMR. 8,10,14 Hence, a large batch of a linear PMMA-co-AEMA SCHEME 1 Synthesis of SCPNs having intramolecular CLs with different lengths. e Calculated assuming 100% mass recovery.…”

“…Recently, we have been studying the use of covalent intramolecular CLs to tune the mechanical properties and mechanochemical response of polymer chains while maintaining the material thermoplastic . Intramolecular CLs connect between two monomer sites within the same chain, folding the polymer into a more compact, yet still soluble, meltable, and therefore processable, polymer architecture, commonly called single‐chain polymer nanoparticles (SCPNs) .…”

“…6,7 Recently, we have been studying the use of covalent intramolecular CLs to tune the mechanical properties and mechanochemical response of polymer chains while maintaining the material thermoplastic. [8][9][10] Intramolecular CLs connect between two monomer sites within the same chain, folding the polymer into a more compact, yet still soluble, meltable, and therefore processable, polymer architecture, commonly called single-chain polymer nanoparticles (SCPNs). 11,12 In recent studies, we demonstrated that SCPNs folded by covalent bonds, while thermoplastic in nature, respond to mechanical stress in a similar way to thermosets, presenting significantly higher rate of mechanochemistry, but demonstrating a significant slower loss in properties.…”