Polycaprolactone blends for fracture ﬁxation in low load-bearing applications Antony Bou-Francis, 1 Marta Piercey, 1 Omar Al-Qatami, 1 Gianfranco Mazzanti, 1 Rabie Khattab , 2 Amyl Ghanem 1,3 1 Department of Process Engineering and Applied Science, Dalhousie University, Halifax, Canada 2 Clinical Nutrition Department, Imam Abdulrahman Bin Faisal University, Dammam, Kingdom of Saudi Arabia 3 School of Biomedical Engineering, Dalhousie University, Halifax, Canada Correspondence to: R. Khattab (E-mail: rykhattab@iau.edu.sa or khattabry@gmail.com) ABSTRACT: There is a need to replace surgical plates and screws in orthopedic surgery. Absorbable polymers are an alternative to metal where load bearing is of a less concern. Polycaprolactone (PCL) is biocompatible, yet it has low mechanical strength and its surface chemistry does not promote cell adhesion. The objective of this work was to create PCL adhesive blends with poly(glycolic) acid (PGA), thermoplastic starch (TPS), chitosan, and tricalcium phosphate (TCP) to be used as potential fracture ﬁxation devices. The differential scanning calorimetry (DSC) data showed that the primary melting points (T m1  C) of blends were often lower than PCL, with the excep- tion of chitosan blends, which may indicate an improvement for surgical use. PCL/PGA blends showed secondary and tertiary melting points (T m ) and enthalpies (ΔH m ) indicating poor miscibility of PGA in the blends. The binary PCL/TCP mixture has a higher enthalpy compared to the binary PCL/PGA blend, but the secondary melting temperature is lower in ternary mixtures. Ternary blends of PCL/PGA/TCP, however, retained the adhesive strength of the parent PCL adhesive while having an improvement in hydrophilicity. These blends are recommended for fracture ﬁxation devices especially in low load-bearing applications such as maxillofacial surgery, orthopedics, and neurosurgery. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48940. KEYWORDS: adhesives; applications; blends; differential scanning calorimetry (DSC); structure–property relationships Received 3 August 2019; accepted 6 November 2019 DOI: 10.1002/app.48940 INTRODUCTION Over the last three decades, a gradual shift from biostable implants to degradable temporary devices has emerged. 1 Synthetic absorb- able polymers are now commercially available as orthopedic devices. A review by Barber 2 categorized these devices as (number of devices in parentheses): fracture ﬁxation (6), interference- ﬁxation screws (6), suture anchors (21), meniscal repair (5), ante- rior cruciate ligament reconstruction (1), and other devices intended for craniomaxillofacial ﬁxation (1). Most of these devices have been prepared using poly(lactic acid) (PLA), poly(glycolic acid) (PGA) and their copolymers 3 (Figure 1). It is interesting that none of the current devices are prepared using polycaprolactone (PCL). PCL is a semi-crystalline aliphatic polyester with low melt- ing point (59–64  C) and glass-transition temperature (-60  C), superior rheological and viscoelastic properties as well as excep- tional blend-compatibility. It has further interesting properties suitable for cartilage tissue engineering applications, such as good biodegradability, biocompatibility, and ﬂexibility. 4 Nevertheless, its hydrophobicity and low surface wettability adversely affect cell attachment and proliferation. Several surface treatments have been attempted to increase its surface hydrophilicity in order to improve the cell–material interfaces. 5,6 PCL has been relatively unused in recent years because the medi- cal devices and drug delivery community considered that faster absorbable polymers had fewer perceived disadvantages associ- ated with the long-term degradation (>2 years) of PCL. However, recent studies have indicated that slower degrading biomaterials (such as PCL) are expected to have a milder inﬂammatory reac- tion with less foreign-body reaction compared to faster degrading biomaterials (such as PGA). 7,8 Furthermore, the advantages of PCL over other absorbable polymers include its tailorable degra- dation kinetics and mechanical properties, ease of manufacturing and shaping into a large range of scaffolds with appropriate pore sizes conducive to tissue in-growth, and the controlled delivery of drugs contained within its matrix. Although a number of drug- delivery devices prepared using PCL already have FDA approval and CE Mark registration, PCL devices have not been widely translated to the clinic. 4,9 © 2020 Wiley Periodicals, Inc. 48940 (1 of 9) J. APPL. POLYM. SCI. 2020, DOI: 10.1002/APP.48940