Plasma Treatment of Polymer Powder as an Effective Tool to Functionalize Polymers: Case Study Application on an Amphiphilic Polyurethane

Abstract

Plasma treatment is a widely applied, easy, fast, and highly reproducible surface modification technique. In this work powder plasma treatment was exploited to expose carboxylic groups along the backbone of a water soluble polymer. Specifically, a custom-made amphiphilic poly(ether urethane) containing Poloxamer® 407 blocks (Mw = 54,000 Da) was first synthesized and its powders were plasma treated in the presence of Acrylic Acid vapor. To maximize –COOH group exposure while preventing polymer degradation, different Ar gas flow rates (i.e., 10, 30, and 50 sccm) were investigated. Upon gas flow increase, significant polymer degradation was observed, with a 35% molecular weight reduction at 50 sccm Ar flow rate. On the other hand, the highest number of exposed carboxylic groups (5.3 × 1018 ± 5.5 × 1017 units/gpolymer) was obtained by setting gas flow at 10 sccm. Hence, a gas flow of 10 sccm turned out to be the best set-up to maximize –COOH exposure while preventing degradation phenomena. Additionally, upon plasma treatment, no detrimental effects were observed in the thermoresponsiveness of polymer aqueous solutions, which was ensured by Poloxamer® 407 blocks. Therefore, the newly developed technology here applied on an amphiphilic poly(ether urethane) could pave the way to the tailored design of a plethora of different multifunctional hydrogels.

Hybrid Injectable Sol-Gel Systems Based on Thermo-Sensitive Polyurethane Hydrogels Carrying pH-Sensitive Mesoporous Silica Nanoparticles for the Controlled and Triggered Release of Therapeutic Agents

“…In fact, at 37 • C both NHP407 and SHP407 systems exhibited ω G /G crossover values lower than 0.1 rad/s and turned out to be in the gel state, although a not complete gel development was achieved. This result can be correlated to the presence in SHP407-based system of a higher number of hydrogen bonds due to the exposure of free -NH 2 groups, which contribute together with hydrophobic interactions to the progressive chain arrangement into micelles and their consequent aggregation to finally form a gel (Aoki et al, 1994;Laurano et al, 2019). This high degree of physical crosslinking within SHP407 gel was probably also responsible for its lower resistance to applied deformation (γ L of 18.6 and 11.6% for NHP407 and SHP407 gels, respectively) and Yield Stress (YS of 1790 and 875 Pa for NHP407 and SHP407 gels, respectively) compared to NHP407-based one ( Figure 1A).…”

“…In this regard, Laurano et al have recently reported a modified synthesis protocol resulting in the introduction along the backbone of a P407-based PEU of approximately 10E20 secondary amino groups/g PEU (Laurano et al, 2020). Another possible route to be investigated consists in adapting the plasma treatment protocol developed by Laurano et al (2019) to expose primary amines along polymer backbone using allylamine as monomer (Jeong et al, 2019) or ammonia gas (Mahmoudifard et al, 2017). In view of the final application of the developed formulation, SHP407 hydrogel injectability, dispersion and gelation in situ within an organism were demonstrated ex vivo using murine cadavers (Figure 4).…”

Thermosensitive Micellar Hydrogels as Vehicles to Deliver Drugs With Different Wettability

“…The P407-based poly(ether urethane) used in this work was synthesised following the pre-polymerisation method recently described by Laurano et al (2019) ( Supplementary Figure S1 ). Specifically, P407 was first dissolved in DCE (20% w/V concentration) at 80°C under continuous nitrogen flow.…”

Using Poloxamer® 407 as Building Block of Amphiphilic Poly(ether urethane)s: Effect of its Molecular Weight Distribution on Thermo-Sensitive Hydrogel Performances in the Perspective of Their Biomedical Application

“…Irrespective of the macrodiol used, both spectra showed the characteristic bands ascribed to newly formed urethane bonds, thus proving the success of the synthesis. Specifically, the bands at 1,720 cm −1 and 1,630 cm −1 can be ascribed to the stretching vibration of carbonyl groups; the band at 3,350 cm −1 can be attributed to the stretching vibration of N-H bonds, while at 1,540 cm −1 the spectrum showed the bending vibration band of N-H bonds together with the stretching vibration band of C-N bonds (Laurano et al, 2019;.…”