ON THE DEVELOPMENT OF CHITOSAN-GRAFT-POLY(N-ISOPROPYLACRYLAMIDE) BY RAFT POLYMERIZATION TECHNIQUE

The present paper aimed the synthesis of a functional biopolymer based on chitosan-graft-poly(N-isopropylacrylamide) (CS-g-PNIPAAm) using the "grafting from" technique via reversible addition-fragmentation chain transfer (RAFT) polymerization. Two different chain transfer agents, both compatible with the acrylic monomer were used. All intermediary products obtained from each step of chemical synthesis were quantified by ATR-FT-IR, H-1-NMR and elemental analysis. Thermal properties confirmed that, with the chemical modification, chitosan structures became more complex and more thermally stable. The grafting efficiency was quantified as 40% and the final copolymer had double functionality, free amino groups and PNIPAAm segments on the side chains. Thanks to this, water solubility, pH and temperature sensitivity were achieved. The particle size of the aqueous solutions increased from 500 nm to 3.5 mu m, with the increase of temperature from 25 to 50 degrees C. The lower critical solution temperature (LCST) of the solution was determined as 38-42 degrees C. CS-g-PNIPAAm could be used as a polymeric carrier within a pharmaceutical formulation for topical applications

Deri Finisajı için Düşük Emülgatör İçerikli Kompozit Yapılı bir Poliakrilik Lateks Sentezi ve Aplikasyonu

A composite polyacrylic latex via two stage seeded emulsion polymerization with low emulsifier content (0.5 wt.%) was synthesized and characterized by means of particle size and zeta potential analysis, FTIR and differential scanning calorimetry (DSC). The results verified a very uniform particle size distribution and good electrostatic stability. The different phases of the composite polymer were evidenced by DSC analysis with two clear phase transitions. The application of the latex on leathers as coating binder revealed good fastness levels to dry/wet rubbing and water spotting. The synthesized composite latex was found to be good candidate for producing cost-effective waterborne binders with good performance

Responsive freeze-drying interpolymeric associations of alginic acid and poly(N-isopropyl acrylamide). Ii. transition and temperature dependence on ph and composition

In a previous study of ours,12 the interpolymeric associations based on alginic acid - poly(N-isopropyl acryl amide) (AgA/PNIPAM) were found to be more stable over the AgA/PNIPAM composition range of 15-70%/85-30%. The present study analyzes the dependence of phase transition temperature on the interpolymeric association composition and pH, by viscometric and spectroscopic measurements. The transition temperature determined over the 30-33 °C range showed a slight increase with increasing the AgA content, along with a possible synergistic effect between temperature and the ionic species within the solution, to which IPC is responsive