Fracture Behavior of Polyrotaxane-Toughened Poly(Methyl Methacrylate)

Abstract

The fracture behavior of polyrotaxane (PR)-modified poly(methyl methacrylate) (PMMA) was investigated. PR is a supramolecule with rings threaded onto a linear backbone chain, which is capped by bulky end groups to prevent the rings from de-threading. The ring structure is α-cyclodextrin (CD), and it can be functionalized to enhance its affinity with the hosting polymer matrix. Adding only 1 wt % of PR containing methacrylate functional groups (mPR) at the terminal of some of the polycaprolactone-grafted chains on CD promotes massive crazing, resulting in a significant improvement in fracture toughness while maintaining the modulus and transparency of the PMMA matrix. Dynamic mechanical analysis and atomic force microscopy studies reveal that mPR strongly interact with PMMA, leading to higher molecular mobility and enhanced molecular cooperativity during deformation. This molecular cooperativity may be responsible for the formation of massive crazing in a PMMA matrix, which leads to greatly improved fracture toughness.

Directly Using Paraffin as the Toughening Agent of Epoxy Composites: An Experimental and Molecular Dynamics Simulation Study

“…A great deal of reports show that the introduction of soft phases such as elastomers, core–shell particles, block copolymers, and interpenetrating networks into the epoxy matrix can greatly improve the toughness. However, the incorporation of the soft phases will lead to the decrease of the glass transition temperature ( T g ) or mechanical properties such as strength, modulus, stiffness, and so on. , Besides, it was also demonstrated that the uniform distribution of rigid particles , in the epoxy matrix can overcome the disadvantages of using soft toughening agents by improving the toughness without sacrificing mechanical properties or T g . However, on the one hand, the uniform distribution of rigid particles is not very easy to be achieved; on the other hand, even if the rigid particles can be uniformly distributed in the epoxy matrix and no aggregation occurs, the processing properties can be greatly reduced due to the increase of the viscosity.…”

Gummy Nanoparticles with Glassy Shells in Electrostatic Nanocomposites

“…Tuning the properties of polymer nanocomposites has been of interest in the field of soft functional materials for many years. − Improving properties such as modulus, toughness, and conductivity can be achieved by introducing nanofillers. These nanofillers are usually inorganic such as silica − and other metal oxides, or gold, or are combined with organic building blocks such as nanocellulose, , block copolymers, and vitrimers. Specific interactions can occur between particles and their constituents on the nano scale leading to unique architectures and properties. ,, For example, cross-linked polydimethylsiloxane, PDMS, or “silicone rubber” often contains a dispersion of nanosilica to impart toughness.…”

“…All-polymer nanocomposites bind dispersions of polymer nanoparticles with other polymers. , Water-stable polymer nanoparticles usually have a hydrophobic core and a hydrophilic polymer shell that stabilizes the particles. ,, As a soft polymer, PDMS is a widely used nontoxic, biocompatible hydrophobic polymer with high thermal resistance and low glass transition temperature, T g . ,− Unfortunately, there is a strong difference in solubility between PDMS and other common polymers such as polystyrene, poly­(methyl methacrylate), or poly­(vinyl chloride) . Its low T g , beneficial for use in elastomeric products, means that PDMS remains liquidlike at room temperature.…”

“…4,14−16 All-polymer nanocomposites bind dispersions of polymer nanoparticles with other polymers. 8,17 Water-stable polymer nanoparticles usually have a hydrophobic core and a hydrophilic polymer shell that stabilizes the particles. 13,18,19 As a soft polymer, PDMS is a widely used nontoxic, biocompatible hydrophobic polymer with high thermal resistance and low glass transition temperature, T g .…”

Preparation of All Amorphous PMMA Resins Based on the Graft Architecture with a Flexible Main Chain for Simultaneous Enhancement of Thermal and Mechanical Toughness

“…Other than the simple blending of different polymers or stress‐induced rejuvenation method, [ 16–19 ] the use of dynamic physical interaction or sliding movement of polyrotaxanes is the recent major approach. [ 20–22 ] In both cases, the incorporation of mobile components into the glassy matrix succeeded in stress dissipation during deformation. As a simpler design, we recently proposed a use of graft architecture to introduce ductile nature into all amorphous glassy acrylic resins.…”