Cloud‐Point Pressure Curves of Ethene/Poly[ethylene‐ co ‐((meth)acrylic acid)] Mixtures

Ethene‐methacrylic acid (MAA) and ethene‐acrylic acid (AA) copolymers of narrow polydispersity and high chemical homogeneity have been synthesized at acid unit copolymer contents up to 9 mol‐% within a continuously operated stirred tank reactor at overall monomer conversions of about 2%. Cloud‐point pressures (CPPs) of mixtures of 3 wt.‐% copolymer in ethene (E) have been measured in an optical high‐pressure cell at pressures and temperatures up to 3 000 bar and 260 °C, respectively. The CPP weakly increases with acid copolymer content up to about 3.5 mol‐%. Toward higher acid contents, the CPP is strongly enhanced, in particular at the lower edge of the experimental temperature range at around 200 °C. This increase in CPP is more pronounced for the AA than for the MAA systems. The data suggest that hydrogen‐bonding interactions are operative in the pressurized E/poly(E‐ co ‐(M)AA) mixtures at temperatures of 260 °C and perhaps even above. E‐AA and E‐MAA copolymers with acid contents of about 5.6 mol‐% have also been completely methyl‐esterified to yield the associated methyl esters. The CPPs of the resulting E‐methyl acrylate and E‐methyl methacrylate copolymers in mixtures with E are significantly below the CPPs of the corresponding E/poly(E‐ co ‐(M)AA) systems.Cloud‐point pressure vs temperature curves for several E/poly(E‐ co ‐methacrylic acid) systems. The subscripts denote copolymer content in mol‐%. A cloud‐point pressure curve for E/polyethylene (PE) is included for comparison.