MISCIBILITY BEHAVIORS OF (ALKYLSULFONYL)METHYL-SUBSTITUTED POLY(OXYALKYLENE) BLENDS

Miscibility behaviors of poly[oxy(alkylsulfonylmethyl)ethylene]s, oxy( alkylsulfonylmethyl)ethylene-co-oxyethylene]s, and oly[oxy-2,2-bis(alk ylsulfonylmethyl)trimethylene]s were studied. A group contribution par ameter for the aliphatic sulfone group was developed and used to calcu late solubility parameters for both oxyethylene series. Though there i s no specific interaction between these polymers, they have similar ba ckbones and the same side chains, and many pairs were found to be misc ible. The poly(oxytrimethylene)s were miscible with certain oxyethylen e homo- and copolymers even when their solubility parameters were very different (Delta delta less than or equal to 1.5 (cal/cm(3))(1/2)). H owever, no polymer was miscible with another containing the same backb one even when their solubility parameters were very close. The miscibi lity range was used to determine solubility parameters for two members of the oxytrimethylene series and a group contribution parameter for the gem-disubstituted disulfone group. When the unoccupied volumes of two miscible polymers are very different, volume contraction and negat ive heat of mixing can be expected; this decreases the free energy of mixing and promotes the miscibility of polymers with relatively large solubility parameter differences. The permeability coefficient and the chemical structure of oly[oxy-2,2-bis(methylsulfonylmethyl)trimethyle ne] imply that its unoccupied volume (probably excluded volume due to poor packing of the bulky substituent) is larger than those of the oth er backbone polymers. Miscible blends of oxytrimethylene polymers with oxyethylene homo- or copolymers showed volume contraction upon mixing . This implies that the monosubstituted oxyethylene polymers can pack into the excluded volume of the 3,3-disubstituted oxytrimethylene poly mers.