Triboluminescence of poly(n-butyl methacrylate)-polyaniline composites

TriboLuminescence (TbL) is defined as the emission of light caused by the application of mechanical energy to a solid (Chandra (1998)). The mechanical action can consist of rubbing, cleaving, tensile deformation, etc. In particular, scratching has proven effective in several materials. During the past few years an increasing number of researchers have studied this phenomenon by using different types of solids (Takada et al. (2000), Chandra (1977), Kitamura et al. (1986), Xu et al. (1999), Hong et al. (2001)). Interestingly, the most common material known to present TbL emission are crystals and very scarce attention has been dedicated to amorphous materials, including polymers. However, some reports on TbL in polymers such as Poly(Methyl MethAcrylate) (PMMA) (Tokhmetov and Vettegen (1990)) and polyvinylidene fluoride (Reynolds (1997)) demonstrate the universality of the phenomenon. In this work we report the TbL properties of Poly(n-Butyl Methacrylate) (PBMA) under scratching. An electrically-conductive polymer, PolyANiline (PANi), was added at different ratios, aiming to control the TbL behaviour. The polyaniline was doped with DodecilBenceneSulfonic Acid (DBSA), which has been reported to improve the compatibility with thermoplastics such as PBMA (CastilloOrtega et al. (2003)) of an electrically-conductive polymeric material (PolyANiline-PANi in the present case) allows the emission properties of PBMA to be controlled almost at will. The PBMA and PBMA-PANi materials were doped with DodecilBenceneSulfonic Acid (DBSA), a commercial substance known to act as an agent to make compatible thermoplastics. Figure 1 shows the emissions detected by the photomultiplier tube from two different samples: the first one (a) from high density polyethylene (HDPE), used as reference, and the second one (b) from PBMA showing clearly the TbL response. The possible mechanisms for this phenomenon are discussed, as well, aiming to propose a whole novel family of luminescent materials.