Thermo-sensitive polymers have gained great interest in recent years due to the unique features facilitating their applications in a variety of areas

such as controlled drug release

biotechnology

separation

etc.They exhibit fast

reversible volume changes around their lower critical solution temperature (LCST).More recently

much attention has been paid to the preparation of ionic thermo-sensitive polymers because polyions are readily adsorbed on the surfaces with opposite charges and polycations have been proposed as novel non-viral vectors for gene delivery.It is well known that PVA is a cost-effective

low toxic and biocompatible polymer.Not only applied to industrial products such as fibers

coatings and films

PVA has also been utilized in biomedical applications

such as artificial kidney

pancreas

etc.In this paper

glycidyltrimethylammonium chloride(GTMAC) and acetaldehyde were selected to modify(poly(vinyl) alcohol)(PVA) in an attempt to render PVA thermo-sensitive and cationic characters

where the GTMAC introduces cationic groups whereas acetaldehyde provides hydrophobic ethyl groups.The structure of modified PVA(CAPVA) was characterized by elemental analysis

surface charge density and NMR.And the thermo-sensitivity or LCST was revealed by using a turbidimeter.It is found that CAPVA is water-soluble and generates clear aqueous solution below LCST.As the temperature rises above LCST

the chains are hydrophobically associated or aggregated

leading to phase separation of the formation of CAPVA agglomerates.The LCST of CAPVA was influenced by the amount of cationic groups

the degree of acetalysis and the concentration of NaCl in solution.The LCST of CAPVA containing more cationic groups and less acetal rings was relatively high(up to 75℃)

which was lowered gradually with the increase of NaCl concenrtration.The LCST of CAPVA can be tailored or adjusted via controlling the densities of cationic groups and acetal rings as well as the electrolyte concentration.