Lactic acid based PEU/HA and PEU/BCP composites: Dynamic mechanical characterization of hydrolysis

Abstract

Lactic acid based poly(ester-urethane) (PEU-BDI) and its composites with 20 and 40 vol.% bioceramic filler were characterized prior to their use as biocompatible and bioabsorbable artificial bone materials. Morphological, dynamic mechanical properties, and degradation of these either hydroxyapatite or biphasic calcium phosphate containing composites were determined. Addition of particulate bioactive filler increased the composite stiffness and the glass transition temperature, indicating strong interactions between the filler and matrix. Materials were sterilized by gamma-irradiation, which reduced the average molecular weights by 30-40%. However, dynamic mechanical properties were not significantly affected by irradiation. Specimens were immersed in 0.85 w/v saline at 37 degrees C for 5 weeks, and changes in molecular weights, mass, water absorption, and dynamic mechanical properties were recorded. All the composite materials showed promising dynamic mechanical performance over the 5 weeks of hydrolysis. Average molecular weights of PEU-BDI and its composites did not change substantially during the test period. PEU-BDI retained its modulus values relatively well, and although the moduli of the composite materials were much higher, especially at high filler content, they exhibited faster loss of mechanical integrity.

Photopolymerization of biomaterials: issues and potentialities in drug delivery, tissue engineering, and cell encapsulation applications

“…All implantable materials/formulations have to satisfy a sterility test, absence of pyrogens and immunogenic molecules 100. The sterilization of either every single formulation component, or the pre‐polymerized formulation or the polymerized matrix, and the sterilization method used can greatly affect both/either the sterility of the product, and/or the degradation pattern and physico‐chemical properties of the polymer network,101–112 and/or the integrity of the molecules entrapped within the matrix 113 In small‐scale experiments polymer networks have been sterilized by (i) filter‐sterilizing the precursor fluid with a 0.2 µm syringe filter;45, 51 (ii) exposing photopolymerized polymer networks to ethylene oxide for 12 h before their utilization;53 (iii) leaving photopolymerized polymer networks in a solution of ethanol:water (70:30) for 3 days before their utilization 30.…”

Synthesis of hydroxyl‐terminated poly(lactic acid) via polycondensation: An equation to predict molecular weight based on the reaction parameters

“…One of the most important approaches for L-lactic acid (LA)-based polymers is to make PLA-based polyurethanes (PUs) to create a biodegradable PU with desirable properties, and many studies have been focused on this purpose. [3][4][5][6][7][8][9] Poly(ester urethanes) based on PLA are made by a two-step process including, first, the synthesis of hydroxyl-terminated poly(lactic acid) (PLA-OH) followed by the synthesis of PU. 10 In the first step, a low-molecular-weight telechelic polymer is synthesized via condensation polymerization in the presence of a catalyst with 1,4-butanediol (1, for hydroxyl termination and control of the molecular weight (MW) of the prepolymer.…”

“…14 The polycondensation route is a convenient process and has been studied by many researchers during the last 2 decades. [4][5][6][7][8]15 The MWs of synthesized telechelic polymers are highly dependent on some of the reaction parameters, such as the reaction time, reaction temperature, pressure, catalyst type, and amount (based on the LA content used) and molar ratio of butanediol (BDO) to LA. 3 From the catalyst standpoint, it has been proved that tin(II) octoate [Sn(Oct) 2 ] is one of the most efficient catalysts for attaining a reliable MW.…”

Amorphous calcium phosphate/urethane methacrylate resin composites. I. Physicochemical characterization

“…ACP was selected as a model CaP due to its compositional and solubility properties [5] and its reportedly high level presence (as much as 9 % by mass) in young bone [6]. The UDMA, PEG-U, and the blend resins were selected as resin matrix binder phase of ACP-filled composites since their polymers contain both hydrophilic and hydrophobic components spanning a range of mechanical compliances, potentially useful in maxillofacial and dental reconstructive devices [7]. These materials also closely correspond to compliant polyurethanes used in cardiovascular applications [8].…”