Mechanoresponsive Hard Elastic Materials Based on Semicrystalline Polymers: From Preparation to Applied Properties

Abstract

This work offers an alternative strategy for the preparation of hard elastic (HE) materials via environmental intercrystallite crazing and subsequent spontaneous strain recovery. Structure and properties of HE materials are characterized: secondary loading in air is accompanied by the development of porosity (up to 40%) with pores below 20 nm; upon unloading, the as-opened porous structure is closed in the elastic manner (strain recovery up to 90%). Upon loading/unloading cycles, the HE samples behave as "living" mechanoresponsive materials with openable and closable mesopores. This strategy has proved to be universal for diverse semicrystalline polymers [high-density polyethylene, polypropylene, poly(tetrafluoroethylene)]. The phenomenon of the forced impregnation of polymer matrixes with target cargo upon cyclic loading offers benefits for the incorporation of diverse additives when the overall uptake can be increased by 500%. The mechanism behind this phenomenon is discussed. Practical benefits of HE polymers and related nanocomposites as applied materials (including antibacterial and photoactive materials) are highlighted.

Hydrophilization of Hydrophobic Mesoporous High-Density Polyethylene Membranes via Ozonation

“…Environmental crazing is known to be the specific mode of plastic deformation of semicrystalline and amorphous glassy polymers, which is accompanied by the development of macroscopic porosity with nanoscale pore dimensions (below 10 nm) [ 33 , 34 , 35 , 36 ]. In the case of semicrystalline polymers, their deformation in the presence of physically active liquid environments (PALE) proceeds via the mechanism of intercrystallite crazing which involves stress-induced cavitation and fibrillation in the amorphous phase upon separation of crystalline lamellae [ 37 , 38 , 39 ].…”

Breathable Materials and Hybrid Nanocomposites with Antimicrobial Activity Based on Porous Poly(ε‐Caprolactone) Obtained via Environmental Crazing

“…The problem concerning the immobilization of an incorporated additive in a polymer matrix has turned out to be solvable with the use of polymer ability to low‐temperature shrinkage ( Figure ). [ 24,55,56 ] For example, the value of the equilibrium shrinkage of PCL fibers crazed in ethanol by 100% has appeared to be 75%. The shrinkage of deformed PCL films decreases with a rise in the tensile strain from 98% (at a strain of 50%) to 87% (at a strain of 200%); that is, as the tensile strain increases, the deformation irreversibility is enhanced due to the destruction of the crystalline framework of the polymer.…”

Biomedical Organic-Inorganic Nanocomposite Materials Based on High-Density Polyethylene and Ultra-High-Molecular-Weight Polyethylene and Silver Nanoparticles

“…In this study, we investigated the possibility to create biomedical hybrid organic-inorganic nanocomposite materials via the formation of silver nanoparticles directly in the polymer bulk, during reduction of the precursors (silver nitrate was used as an example) inside the mesoporous matrices of high-density polyethylene (HDPE) and ultra-high-molecular-weight polyethylene (UHMWPE) prepared via the polymers deformation in the presence of physically active liquid medium (the intercrystallite crazing mechanism) [14][15][16]. The nanosized pores of the polymer matrix could act as microreactors for subsequent in situ reduction of the metal ions into the zero-valence state and the formation of silver nanoparticles in the polymer bulk.…”

“…The distribution was unimodal with a pronounced maximum at 12 nm and relatively wide, the span being between 2-4 and 13-20 nm. It should be noticed that the most probable size of a single silver nanoparticle (12 nm) exceeded the average diameter of the pores in the mesoporous polymer matrix (6 nm), which could be explained by the fact that the development of porosity via intercrystallite crazing of partially crystalline polymers occurred via cavitation and fibrillization of the amorphous phase existing in the high-elastic state at room temperature [15,16]. In that case, the introduced low-molecular additive was completely localized in the softened amorphous phase of the polymer (the fibrils and the pores separating them).…”