# Physical, Thermal, and Mechanical Characterization of PMMA Foils Fabricated by Solution Casting
## 1 Introduction  
Poly-methyl methacrylate (PMMA) is an amorphous thermoplastic polymer with moderate mechanical properties at room temperature. At a strain rate of 10\({}^{-3}\) s\({}^{-1}\), the tensile strength (UTS) has a value of 70 MPa, elastic modulus (E) of 3.3 GPa, and low density as compared to metallic materials of 1.19 g cm\({}^{-3}\). Importantly, PMMA is biocompatible, making it highly desirable for use in not only electronics, microelectromechanical systems (MEMS), and micro-optics but also biomedical and microfluidic devices [1; 2; 3]. PMMA has many advantages over other transparent polymers (e.g., polystyrene, PC, etc. ), such as high resistance to UV light and weathering and excellent light transmission. PMMA is produced from the monomer methyl methacrylate. It is a colorless polymer available in the form of powders, pellets, granules, and sheet forms. Thin polymer films are usually obtained by solution casting for many applications, such as paints, varnishes, and adhesives. The properties of a polymer film obtained from a solution can differ from the original bulk polymer, which may have some consequences on the behavior of the final film. PMMA foils are produced by the casting method followed by polymerization and molding steps. Polymeric materials depend strongly on the rheological behavior of surfaces during casting processing, and the mechanical behavior of the samples depends upon the final products. However, rare attention has been focused on the physical, structural, and mechanical properties of PMMA foils prepared by the solution casting method. The samples prepared from various solid-to-liquid ratios (S/L ratios) with solvent toluene by solution casting method could be different in thermal, and mechanical properties. PMMA is commonly known as acrylic glass or plexiglass polymer that could be used as the main component of positive resists for UV photolithography [4; 5]. PMMA is considered an imprintable material for hot-embossing soft lithography because of its transparency in the visible spectrum [6]. It is widely used in optical applications, especially as a matrix for nonlinear optical composite materials [7; 8]. PMMA polymer considers one of the individual components of composite structure because of its shape memory effect and is biocompatible in nature. Various techniques have been implemented to combine polymer into the substrate, such as spin coating and injection molding methods [9; 10; 11]. The interfacial adhesion of polymer onto the substrate is a crucial factor for the application of the composites in aggressive environments [12]. PMMA is commonly used in denture material with poor antimicrobial effects [13]. PMMA composite plays a significant role in modern optical devices due to its transparency and high hardness nature [14]. Various surface treatment methods such as UV irradiation have been used to increase the adhesion of PMMA polymer [15]. Prior to use as one of the components in composite materials, it is essential to study the individual component behavior of PMMA polymer prepared by the as-cast method. There are extensive studies that have been carried out in the literature about PMMA samples cast from various solvents. The influence of various solvents was studied on the morphology of PMMA foils towards the mechanical properties [16]. The study also focused on the effect of solvents on the structural behavior of the relaxation temperature of as-cast PMMA foils [17], as the effect of solvents influences acid-base interaction between the basic sites of PMMA and the acid character of the solvent. The effect of ultrasonic fields on the dilution of PMMA in the solvents has been studied for PMMA films obtained by the drop-casting method. The ultrasonic vibration decreases the amount of residual solvent in the film to one-twelfth of the value, which occurs by spontaneous evaporation [18].