Effect of phosphate-based glass fibre surface properties on thermally produced poly(lactic acid) matrix composites

Abstract

Incorporation of soluble bioactive glass fibres into biodegradable polymers is an interesting approach for bone repair and regeneration. However, the glass composition and its surface properties significantly affect the nature of the fibre-matrix interface and composite properties. Herein, the effect of Si and Fe on the surface properties of calcium containing phosphate based glasses (PGs) in the system (50P(2)O(5)-40CaO-(10-x)SiO(2)-xFe(2)O(3), where x = 0, 5 and 10 mol.%) were investigated. Contact angle measurements revealed a higher surface energy, and surface polarity as well as increased hydrophilicity for Si doped PG which may account for the presence of surface hydroxyl groups. Two PG formulations, 50P(2)O(5)-40CaO-10Fe(2)O(3) (Fe10) and 50P(2)O(5)-40CaO-5Fe(2)O(3)-5SiO(2) (Fe5Si5), were melt drawn into fibres and randomly incorporated into poly(lactic acid) (PLA) produced by melt processing. The ageing in deionised water (DW), mechanical property changes in phosphate buffered saline (PBS) and cytocompatibility properties of these composites were investigated. In contrast to Fe10 and as a consequence of the higher surface energy and polarity of Fe5Si5, its incorporation into PLA led to increased inorganic/organic interaction indicated by a reduction in the carbonyl group of the matrix. PLA chain scission was confirmed by a greater reduction in its molecular weight in PLA-Fe5Si5 composites. In DW, the dissolution rate of PLA-Fe5Si5 was significantly higher than that of PLA-Fe10. Dissolution of the glass fibres resulted in the formation of channels within the matrix. Initial flexural strength was significantly increased through PGF incorporation. After PBS ageing, the reduction in mechanical properties was greater for PLA-Fe5Si5 compared to PLA-Fe10. MC3T3-E1 preosteoblasts seeded onto PG discs, PLA and PLA-PGF composites were evaluated for up to 7 days indicating that the materials were generally cytocompatible. In addition, cell alignment along the PGF orientation was observed showing cell preference towards PGF.

Mechanical behaviour of degradable phosphate glass fibres and composites—a review

“…They studied the change in fibre solubility and surface hydrophilicity produced by the incorporation of SiO 2 due to its ability to disrupt the PG network. As seen with previous studies, the incorporation of 10 mm length, ≈10-20 μm diameter PGFs in a PLA or PCL matrix (≈0.18 V f ) resulted in an increase to the flexural strength and elastic modulus [33,68]. Comparisons of degradation in distilled water or PBS revealed that the 10 mol% Fe 2 O 3 composites showed a lower weight loss and greater retention of mechanical properties compared to the 5 mol% SiO 2 samples.…”

“…For PGF reinforced degradable polymer composites, typically fibre diameters of ≈20 μm have been used [31][32][33][34][35] similar to the 10-20 μm fibre diameters found in commercially available fibre reinforced composites. This is due to the high aspect ratio (i.e.…”

In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties

“…Biocompatibility of both PCL (approved by FDA) and of phosphate based glass fibre (PGF) has been well investigated and both are known to be bioresorbable, which makes these materials favourable candidates for bone repair applications [3][4][5][6]. Most recently, PGF has been used as reinforcement for developing fully bioresorbable polymer composites [2,7,8]. PGFs are able to dissolve completely within aqueous media and their dissolution rate can be adjusted easily by altering the glass composition [2].…”

Chitosan as a Coupling Agent for Phosphate Glass Fibre/Polycaprolactone Composites

“…However, the application of polymer composites, such as PGF/PCL, is limited by the rapid loss of their strength profiles after exposure to an aqueous physiological environment, which has been suggested to be due to loss of their interfacial properties [5]. Recently, coupling agents have been explored to enhance the interfacial properties of fibre/polymer composites [6,7]. Chitosan (CS) has a number of properties that make it a suitable candidate as an interface agent for PGF/PCL composites.…”