Synthesis and properties of surfactants for carbon nanotubes based on copolymers of 2-N-morpholinoethyl methacrylate with dodecyl methacrylate and styrene

The copolymerization reactivity ratios for 2-N-morpholinoethyl methacrylate (MEMA) with dodecyl methacrylate (DDMA) or styrene (ST) were estimated. The efficiency of the prepared polymers for dispersion of MWCNT in toluene was also studied. A wide range of copolymer compositions (all 10 mol% steps) were prepared using tert-butyl peroxy-2-ethylhexanoate (0.02 mol dm−3) as initiator isothermally (70 °C) to low conversions (< 10 wt%). In the case of DDMA/MEMA copolymerization, there is a slight tendency for both monomers to react more with MEMA. The reactivity ratios obtained are r(DDMA) = 0.86 and r(MEMA) = 1.05. The reactivity ratios for the copolymerization of ST/MEMA are both <1 and are r(ST) = 0.35 and r(MEMA) = 0.59, indicating a higher reactivity of each monomer with the other monomer. The addition of small amounts (10 mol%) of MEMA to DDMA homopolymer significantly increases its thermal stability (the temperature at 50 wt% loss is 46 °C higher). For ST/MEMA, the addition of MEMA gradually decreases the thermal stability (the temperature difference at 50 wt% loss between the homopolymers is 25 °C). The best dispersion of MWCNT in toluene is obtained with the ST/MEMA copolymer containing 42 mol% MEMA, as shown by UV–Vis measurements and visual inspections after the gravity test. The obtained results contribute to the further development of polymeric surfactants and stimuli-responsive polymers.