(Quaternized/betainized) amino-based amphiphilic block copolymers: quantitative composition characterization via FTIR and Thermogravimetry

The objective of the present study is the introduction of well known and readily accessible analytical methods as FTIR, thermogravimetric (TGA) and evolved gas analysis (EGA) for quantitative determination of the degree of polymerization (DP) and degree of quaternization (DQ)/betainization (DB) of amino-based amphiphilic block copolymers. For this purpose a series of amphiphilic poly(dimethylsiloxane)-b-poly[2-{dimethylamino)ethyl methacrylate] (PDMS-b-DMAEMA) diblock copolymers with DP of the PDMAEMA-block ranging from 22 to 162 was synthesized by atom transfer radical polymerization and analyzed by 1H NMR, ATR-FTIR and TGA-co-EGA. The determined composition results have shown linear correlation between the FTIR or TGA and the 1H NMR data and equations allowing the quantitative calculation of PDMAEMA-block DP were found. The errors estimated by ATR-FTIR were less than 1.5%. Further, the PDMAEMA-block was quaternized (or betainized) with DQ (or DB) from 25 % to 100 % and analyzed by TGA-co-EGA. Again, a linear correlation between the quaternized (betainized) PDMAEMA-block mass fraction and the DQ (DB) degrees was obtained by 1H NMR.