Preparation of oxygen gas barrier polypropylene films by deposition of SiOx films plasma-polymerized from mixture of tetramethoxysilane and oxygen

Biodegradable PLA/PBSA Multinanolayer Nanocomposites: Effect of Nanoclays Incorporation in Multinanolayered Structure on Mechanical and Water Barrier Properties

Biodegradable PLA/PBSA multinanolayer nanocomposites were obtained from semi-crystalline poly(butylene succinate-co-butylene adipate) (PBSA) nanolayers filled with nanoclays and confined against amorphous poly(lactic acid) (PLA) nanolayers in a continuous manner by applying an innovative coextrusion technology. The cloisite 30B (C30B) filler incorporation in nanolayers was considered to be an improvement of barrier properties of the multilayer films additional to the confinement effect resulting to forced assembly during the multilayer coextrusion process. 2049-layer films of ~300 µm thick were processed containing loaded PBSA nanolayers of ~200 nm, which presented certain homogeneity and were mostly continuous for the 80/20 wt% PLA/PBSA composition. The nanocomposite PBSA films (monolayer) were also processed for comparison. The presence of exfoliated and intercalated clay structure and some aggregates were observed within the PBSA nanolayers depending on the C30B content. A greater reduction of macromolecular chain segment mobility was measured due to combined effects of confinement effect and clays constraints. The absence of both polymer and clays interdiffusions was highlighted since the PLA glass transition was unchanged. Besides, a larger increase in local chain rigidification was evidenced through RAF values due to geometrical constraints initiated by close nanoclay contact without changing the crystallinity of PBSA. Tortuosity effects into the filled PBSA layers adding to confinement effects induced by PLA layers have caused a significant improvement of water barrier properties through a reduction of water permeability, water vapor solubility and water vapor diffusivity. The obtaining barrier properties were successfully correlated to microstructure, thermal properties and mobility of PBSA amorphous phase.

Fabrication of micropatterns on polypropylene films via plasma pretreatment combined with UV-initiated graft polymerization

In this study, micropatterns on polypropylene films were fabricated via plasma pretreatment and UV-initiated graft polymerization. Firstly, radio-frequency plasma, which does not significantly influence bulk attributes of substrates due to limited penetration depth, was utilized to activate polypropylene films. Then, different sizes of micropatterns of poly(hydroxyethyl methacrylate) (PHEMA) were fabricated on the polypropylene films via UV-initiated graft polymerization of hydroxyethyl methacrylate by using photo-masks. Scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle (CA) were employed to characterize changes of pristine polypropylene films and modified ones in surface morphology, roughness, hydrophilicity, free energy and the surface chemical composition. All of these confirmed the successful grafting of different sizes of PHEMA micropatterns on the polypropylene surface. Furthermore, the influence of PHEMA micropatterns on cell proliferation and cytotoxicity was evaluated in vitro. Analysis of cell behaviour indicated that PHEMA micropatterns of the appropriate size can promote cellular adhesion and proliferation, and the PHEMA-micropatterned polypropylene films had good biocompatibility. The approach presented here provides an alternative to synthesize on the surface of polypropylene films' micropatterns with the aim of using them in a diverse array of applications.

A case study exploring the impact of an oxygen barrier coating on formulation stability, in-vitro dissolution and bioperformance

Objectives

The impact of a carmellose sodium (sodium carboxymethycellulose)-based coat (Opaglos 2) on the stability of an oxygen-sensitive compound A and in-vitro dissolution and bioperformance of compound B has been investigated.

Methods

Tablets containing compounds A and B were coated with various weight gains of Opaglos 2 and a comparative elegance coating (poly(vinyl alcohol)-based Opadry II). Film-coated tablets were assessed for oxidative degradation under accelerated stability conditions (30°C/65% RH and 40°C/75% RH).

Key findings

An apparent rank order of restriction of oxygen (O2) permeability afforded by the coatings was observed, with only higher Opaglos 2 coating weight gains (6 and 8% w/w) providing adequate oxidative degradation stability for up to 52 weeks. Improved stability at the higher coating weight gains was attributed to incomplete polymeric film formation at lower coating weight gains. The 6% and 8% w/w Opaglos 2 formulations showed dissolution retardation compared with elegance-coated formulations in USP dissolution apparatus II, predicting significant impact on formulation bioperformance. However, pharmacokinetic studies in Beagle dogs showed similar bioperformance for all formulations.

Conclusions

The Opaglos 2 coating system evaluated in these studies afforded adequate protection from oxidative degradation with no negative impact on bioperformance as compared to elegance coating. However, further studies are needed using several compounds to assess the broader applicability of these coatings.

Plasma surface modification of cyclo-olefin polymers and its application to lateral flow bioassays

The modification of cyclo-olefin polymer Zeonor by plasma-enhanced chemical vapor deposition to form a silica-like surface and evaluation of its application for lateral flow bioassays applications are discussed in this study. The SiOx layer was extensively characterized using contact angle measurements, atomic force microscopy, and Fourier transform infrared spectroscopy in attenuated total internal reflectance mode where the presence of a uniform SiOx film was clearly identified. The SiOx modification resulted in a surface with enhanced wettability and excellent fluidic properties when combined with a hot-embossed micropillar capillary fill-based substrate. The SiOx surface also had the ability to accelerate the clotting of human plasma, which may have application in certain types of blood coagulation assays.