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The wet spinning of cytocompatible, bioresorbable, and knittable chitosan (CTS) monofilaments would be advantageous for a variety of surgical applications. The complexation capacity of chitosan with Cu2+or Zn2+can be leveraged to enhance its antibacterial activity, but not at the expense of cytocompatibility. In this work, a wet-spinning process was adapted for the in situ incorporation of Cu2+or Zn2+with chitosan dopes to produce monofilaments at different drawing ratios (τtot) with various cation/glucosamine molar ratios, evaluated in the fibers (rCu,fand rZn,f). Cytocompatibility and antibacterial activity of wet-spun monofilaments were, respectively, quantified by in vitro live-dead assays on balb 3T3 and by different evaluations of the proliferation inhibition of Staphylococcus epidermidis(Gram+) and Escherichia coli(Gram−). Knittability was tested by a specific tensile test using a knitting needle and evaluated with an industrial knitting machine. It was found that rCu,f= 0.01 and rZn,f= 0.03 significantly increase the antibacterial activity without compromising cytocompatibility. Wet spinning with τtot= 1.6 allowed the production of knittable CTS-Cu monofilaments, as confirmed by knitting assays under industrial conditions.

Polyimides are commonly synthesized in a 2-step solution polymerization process. Such process requires long reaction times as well as specific care due to the use of potentially harmful solvents. In the present study, the total reaction time for producing polyimides has been lowered to less than 10 min by using a solvent-free continuous reactive extrusion process. The proof of concept was determined with the system based on 3,3′,4,4′-benzophenone-tetracarboxylic dianhydride (BTDA) and an aliphatic diamine, Jeffamine D-230 within a microextruder. Degrees of conversion to polyimide, determined with 13C NMR and DSC analysis, are over 90 mol % after 5 min of extrusion at 180 °C, 200 °C, and 225 °C, respectively. These syntheses were then transferred to a twin-screw extruder to form linear aliphatic-aromatic polyimides with two types of dianhydride: BTDA and pyromellitic dianhydride (PMDA). Comparison with a conventional solution polymerization process showed no significant differences in the polymers characteristics. The polyimides produced with this method presented glass transition temperatures ranging from 5 to 90 °C. The number-average molar masses measured were between 11 000 and 15 000 g·mol–1.

Nanostructurated polyamide-based blends were synthesized by reactive extrusion with multifunctional amine-terminated polyethers in a twin-screw extruder. All the reactive blends exhibited a noticeable reduction of the viscosity (up to 50%), while only the systems synthesized with a small amount of the trifunctional Jeffamine T-403 (0.7 wt %) depicted an increase of the Young’s modulus and yield strength by 20 and 13%, respectively, compared to the neat polyamide. The amorphous phase mobility and tensile properties modifications were explained by the crystalline nanostructure evolution of the chemically modified polyamide 6 (PA6). For the smallest quantity of amine, chains mobility evolutions in the amorphous phase of the blends PA6/T-403 were associated with the mobile amorphous fraction/rigid amorphous fraction (RAF) ratio. The material stiffening was not only due to a higher RAF content but also due to thicker crystalline lamellae. On the contrary, a difunctional diamide, Jeffamine D-400, led to chain scissions with no modification of the RAF content.

To better understand the processing and final properties of multilayer films obtained by layer forced assembly in coextrusion as well as their structure morphology, the present study focuses on model films with LDPE as the base polymer. More specifically, the layer confinement of LDPE by a glassy amorphous polymer (here, PC or PS) was investigated. First, the viscosity and elasticity ratios of the different neat polymers were measured by rheological tests to simulate the processing conditions in the feedblock and multipliers during coextrusion. These results together with the observation of film transparency at the macroscopic scale and the layer breakup phenomena between layers at the microscopic scale enabled us to build a comprehensive stability map rationalizing the conditions required for a well-controlled multinanolayer architecture. Second, the morphology of the coextruded films was analyzed by SEM and TEM. The onset of the layer breakup in the LDPE/PS system was determined at 2048 layers with a layer thickness of 95 nm, while in the LDPE/PC system, it was at 256 layers with a layer thickness of 980 nm. The layer breakup happened at a fewer number of layers for the LDPE/PC system due to the viscoelastic mismatched properties between the base polymers. Interestingly, we have demonstrated that it is nonetheless possible to prepare some nanolayer structures with 16,380 layers of the PS/LDPE system with some defects but still maintain an overall property improvement despite their high mismatched viscoelastic properties. Finally, the orientation and crystalline structure of the coextruded films were characterized by 2D-WAXS and DSC, and the ultimate properties of the films were determined through tensile testing. The geometrical confinement of the LDPE nanolayer did not affect the thermal crystalline properties of LDPE chains, but it affected the crystalline morphologies as well as the final mechanical response of the obtained multilayer films.

We report the fabrication and the use of a bioinspired synovial fluid acting as a lubricant fluid and antiwear agent at soft and porous chitosan hydrogel tribopairs. This synthetic synovial fluid is composed of sodium hyaluronate (HA) and a bottle–brush polymer (BB) having a polycationic attachment group and polyzwitterionic pendant chains. The 2.5%w/wchitosan hydrogel plugs are organized in a bilayered structure exposing a thin and dense superficial zone (SZ), covering a porous deep zone (DZ), and exhibiting microchannels perpendicularly aligned to the SZ. Using a low-load tribometer, the addition of HA lubricating solution at the hydrogel–hydrogel rubbing contact drastically decreased the coefficient of friction (CoF) from μ = 0.20 ± 0.01 to 0.04 ± 0.01 on the DZ configuration and from μ = 0.31 ± 0.01 to 0.08 ± 0.01 on the SZ surface when increasing the HA concentration from 0 to 1000 μg/mL and its molecular mass from 10 to 1500 kDa, similar to what was found when using the BB polymer alone. When combining the BB polymer and the 1500 kDa HA, the CoF remained stable at μ = 0.04 ± 0.01 for both studied contact configurations, highlighting the synergistic interaction of the two macromolecules. Hydrogel wear was characterized by assessing the final gel surface roughness by the means of an interferometer. Increasing HA concentration and molecular weight plus the addition of the BB polymer led to a dramatic surface wear protection with a final gel surface roughness of the hydrogels similar to the untested gels. In brief, the BB polymer in combination with high molecular weight HA is a potential lubricating fluid as well as a wear resistant agent for soft materials lubrication and wear protection.

It is known that the macroscopic properties of multilayer polymer films are largely dominated by the diffuse interphase formed via interfacial diffusion between neighboring layers. However, not much is known about the origin of this effect. In this work, we reveal the role of interfacial diffusion and the diffuse interphase development in multilayer polymer films, based on a compatible poly(vinylidene fluoride)/poly(methyl methacrylate) system fabricated by forced-assembly micro-/nanolayer coextrusion. Interestingly, the layer morphology is found to prevail in all investigated multilayer films, even for the nanolayered system where the interdiffusion is substantial. It is also demonstrated that, in the presence of macromolecular and geometrical confinements, interfacial diffusion significantly alters the crystalline morphology and microstructure of the resulting micro-/nanolayered films, which leads to quantitatively different dielectric and rheological properties. More importantly, the combination of dielectric relaxation spectroscopy and energy-dispersive X-ray analysis further reveals that multiple diffuse interphases with various length scales exist in the multilayer structures. The presence of these multiple interphases is explained in terms of a proposed physical picture for the interdiffusion of fast-mode mechanism occurring in the coextrusion process, and their length scales (i.e., interphase thicknesses) are further mapped quantitatively. These findings provide new insights into the effects of interfacial diffusion and diffuse interphases toward tailoring interfaces/interphases in micro-/nanolayered polymer structures and for their advanced applications.

A guideline for the synthesis of poly(acrylic acid) brushes on planar silica surfaces by the “grafting‐onto” approach is described. It is demonstrated that some thermal precautions must be taken to obtain extended brushes. It is also shown that neutron reflectivity is well suited for the characterization of each step of the synthesis, while it is (unfortunately) rarely used for that purpose. The steps are the following: first, the substrates are covered with a self‐assembled monolayer of epoxy‐terminated molecules; then, the poly(tert‐butyl acrylate) brushes are built using preformed and end‐functionalized chains; finally, the deprotection of the ester group is performed using a pyrolysis reaction to convert the poly(tert‐butyl acrylate) brushes into poly(acrylic acid) brushes.

Current microfluidic techniques are powerful to study bacteria and determine their response to antibiotic treatment, but they are currently limited by their complex manipulation. Chitosan films are fully biocompatible and could thus be a viable replacement for existing commercial devices that currently use polylysine. Thus, the low cost of chitosan slides and their simple implementation make them highly versatile for research as well as clinical use.