Abstract:
The research aimed to study the preparation of high performance poly(methyl methacrylate-acrylic acid-divinylbenzene) (P(MMA-AA-DVB)) microcapsules encapsulating highly effective octadecane (OD) without supercooling for the preparation of thermal adaptable cloth prototype.
Firstly, the P(MMA-methyl acrylate (MA)-DVB) microcapsules were prepared by microsuspension iodine transfer polymerization (ms ITP). The influences of MA and DVB contents on the morphology, thermal properties and stability of microcapsule were investigated. The prepared microcapsules were spherical in shape with a dent at their surface by using 30 % of MA and 20% of DVB wt. The latent heats of melting (224 J/g-OD) and crystallization (246 J/g-OD) of the encapsulated OD were close to those of the original OD (245 and 251 J/g-OD, respectively). After that, the hydrolysis was carried out to prepare P(MMA-AA-DVB) microcapsules having -33 mV zeta potential value representing carboxyl groups formation at microcapsule surface. However, the crystallization temperature (T [subscript]C) of the encapsulated OD was significantly decreased from 25°C to 17°C which was called supercooling. Therefore, the addition of nucleating agents (1-octadecanol, Rubitherm 58 and chloroacetic acid) at various contents was investigated to study the reduction of supercooling. It was found that 1-octadecanol provided the best result. From the experiments, T[subscript]C of the encapsulated OD using 5 % wt of 1-octadecanol increased up to 24°C which was close to that of bulk OD while the latent heats were constant. After that, the obtained microcapsules were subsequently coated on the cotton fabric by pad-dry-cure method to prepare thermal adaptable cloth. It was found that P(MMA-AA-DVB) microcapsules were coated more effectively on fabric than P(MMA-MA-DVB) microcapsules. This was due to the interaction of carboxyl group on the microcapsules surface with functional group of fabric.
Consequently, it can be concluded that the P(MMA-AA-DVB) encapsulated OD with excellent thermal properties could be prepared by ms ITP followed by hydrolysis. The obtained microcapsules were effectively coated onto fabric without external binder because of the interaction of microcapsules surface functional group with fabric.