Preparation Of Interpenetrating Polymer Networks Research Articles

Preparation of IPNs SBS/PBMA-b-PMA and Effect of Compatibility with PVC

Interpenetrating polymer networks (IPNs) Poly(styrene-butadiene-styrene)/Poly(n-butyl methacrylate-b-methyl acrylate) (SBS/PBMA-b-PMA) was prepared by atom transfer radical polymerization (ATRP) and characterized by FT-IR, 1H NMR and TEM. The TEM photos illustrated that SBS/PBMA-b-PMA formed an obvious core-shell structure, with cross-linked SBS/PBMA core and linear PMA shell. The compatibility of IPNs with PVC was studied using SEM and DSC instruments. The mixed polymers displayed one Tg (Tg=79.4°C, ΔTg=32.5°C) and showed good compatibility. The SEM fracture surface morphologies displayed partial feature of ductile fracture different form neat PVC.

Effects of reaction temperature and reaction time on positive thermosensitivity of microspheres with poly(acrylamide)/poly(acrylic acid) IPN shells

We have successfully prepared monodispersed positively thermoresponsive core-shell hydrogel microspheres with poly(acrylamide- co-styrene) [P(AAM- co-St)] cores and IPN(interpenetrating polymer network)-based shells composed of poly(acrylamide)/poly(acrylic acid). The submicron-sized monodispersed P(AAM- co-St) core seeds were prepared by using a surfactant-free emulsion polymerization method, and the IPN-based shell layers were fabricated onto the core seeds by using a method of sequential IPN synthesis. Effects of reaction time and reaction temperature during preparation of IPN on the particle size, monodispersity, and thermoresponsive characteristics of microspheres were investigated. The results show that the sizes of particles with IPN shell layer are smaller than that of seeds, and the change of monodispersity among them is not obvious and the monodispersity of particles prepared under higher reaction temperature is higher than that of seeds and those particles prepared under lower reaction temperature. With increasing reaction time, thermoresponsive characteristics of microspheres increases. While thermoresponsive characteristics of microspheres decreases sharply with increasing reaction temperature. The results display preparation of IPN-structured microspheres is so careful to need longer reaction time and lower reaction temperature.

Synthesis and swelling behaviour of interpenetrating network polymers of poly(vinyl alcohol) and poly(acrylamide-co-potassium methacrylate)

A series of interpenetrating polymer networks (IPN) based on poly(vinyl alcohol) and poly(acrylamide-co-potassium methacrylate) were synthesized. The synthesis was effected by a semi-IPN method polymerizing an aqueous solution of acrylamide and potassium methacrylate using the APS/TMEDA initiating system with a cross-linker, in the presence of poly(vinyl alcohol). Four different cross-linkers were employed in the preparation of IPNs. The swelling behaviour of the IPNs was monitored as a function of acrylamide and potassium methacrylate ratios. The IPNs were synthesized by varying the cross-linker concentration and the experimental results showed that the cross-linker concentration is of great influence on the swelling behaviour. The network formation of IPNs cross-linked with various cross-linkers at two different concentrations was studied in detail by scanning electron microscopy (SEM). The IPNs being ionic, swelling is affected by the ionic strength as well as by the pH of the medium. Further the effect of simulated biological fluids on the swelling behaviour of PVA/poly(AAm-co-KMA) IPNs was also investigated.