engleski

Reactivity ratios and copolymer properties of 2-(diisopropylamino)ethyl methacrylate with methyl methacrylate and styrene

Free radical copolymerization kinetics of 2- (diisopropylamino)ethyl methacrylate (DPA) with styrene (ST) or methyl methacrylate (MMA) was investigated and the obtained corresponding copolymers were characterized. Polymerization was performed by using tert-butyl peroxy-2- ethylhexanoate (0.01 mol dm-3) as initiator, isothermally (70 oC) to low conversions (< 10 wt. %) in a wide range of copolymer compositions (every 10 mol-% steps). The reactivity ratios of the monomers were calculated by linear Kelen-Tüdős (K-T) and non-linear Tidwell-Mortimer methods. The reactivity ratios for MMA/DPA were found to be r1 = 0.99 and r2 = 1.00 (K-T), r1 = 0.99 and r2 = 1.03 (T-M) and for ST/DPA system r1 = 2.74, r2 = 0.54 (K-T) and r1 = 2.48, r2 = 0.49 (T-M). It can be concluded that copolymerization of MMA with DPA is ideal while copolymerization of ST with DPA has a small but noticeable tendency for block copolymer building. The probabilities for formations of dyad and triad monomer sequences in dependence of monomer compositions were calculated from the obtained reactivity ratios. The molar mass distribution, thermal stability and glass transition temperatures of synthesized copolymers were determined. Hydrophobicity of copolymers depending on the composition was determined by contact angle measurements and it decreases from hydrophobic PS and PMMA to hydrophilic DPA. Copolymerization reactivity ratios are crucial for the control of copolymer structural properties and conversion heterogeneity that highly influences its application properties as rheology modifiers of lubricating oils or in drug delivery systems.

2-(diisopropylamino)ethyl methacrylate ; free radical copolymerization ; reactivity ratios ; comonomer sequence distribution ; copolymer properties

Glavni autori: Fabio Faraguna i Ante Jukić