Intrinsic viscosity terpolymers

Anionic polymerization techniques were also critical for the synthesis of a model cyclic triblock terpolymer [cyclic(S-fo-I-fr-MMA)] [196]. The linear cctw-amino acid precursor S-fr-I-fr-MMA was synthesized by the sequential anionic polymerization of St, I and MMA with 2,2,5,5-tetramethyl-l-(3-lithiopropyl)-l-aza-2,5-disilacyclopentane as the initiator and amine generator, and 4-bromo-l,l,l-trimethoxybutane as a terminator and carboxylic acid generator. Characterization studies of the intermediate materials as well as of the final cyclic terpolymer revealed high molecular and compositional homogeneity. Additional proof for the formation of the cyclic structure was provided by the lower intrinsic viscosity found for the cyclic terpolymer compared to that of the precursor. 

An appropriate formalism for Mark-Houwink-Sakurada (M-H-S) equations for copolymers and higher multispecies polymers has been developed, with specific equations for copolymers and terpolymers created by addition across single double bonds in the respective monomers. These relate intrinsic viscosity to both polymer MW and composition. Experimentally determined intrinsic viscosities were obtained for poly(styrene-acrylonitrile) in three solvents, DMF, THF, and MEK, and for poly(styrene-maleic anhydride-methyl methacrylate) in MEK as a function of MW and composition, where SEC/LALLS was used for MW characterization. Results demonstrate both the validity of the generalized equations for these systems and the limitations of the specific (numerical) expressions in particular solvents. 

We attempt here to develop a mathematical expression for the dependence of the dilute solution intrinsic viscosity of multispecies polymers on both molecular weight and polymer composition with some broad degree of generality and to particularize the result for the specific cases of copolymers and terpolymers such as SAN and S/MA/MM. The details of the derivation are specific to polymers resulting from addition polymerization across a single double bond in each monomer unit. In principle the approach may be expanded to other schemes of polymerization so long as... 

The polymer samples studied here fall into three distinct categories. Data from two sample populations have been combined in the SAN copolymer study. A group of SAN materials having compositions ranging from 42 (wt)% AN to 82% AN were polymerized and characterized quite some time ago (1972), with intrinsic viscosities determined only in DMF. Very recently, a second group of SAN s with compositions from 5 (wt)% to 48% AN, as well as one sample of polystyrene (0% AN), were polymerized and characterized, with intrinsic viscosities determined in DMF, THF, and MEK. These two populations are differentiated in the Results section by the designations "old data" and "new data". The third category of samples is that of S/MA copolymers and S/MA/MM terpolymers, with intrinsic viscosities measured only in MEK. 

Figure 4. Intrinsic viscosities of S/MA and S/MA/MM samples in MEK solvent vs. the terpolymer parameter,...

Pentachlorophenyl acrylate, (1), was terpolymerized with methyl methacrylate (MMA) and n-butyl acrylate (nBA) (Scheme III) to give a latex containing 537 solids and a pll of 4.7 which was adjusted to 6.8 by adding aqueous NaOH. The latex was stable up to pH =10. A small aliquot vzas coagulated and the resulting polymer purified. Its intrinsic viscosity was 3.1 /g and analysis indicated 2 mole percent (1), 587 CIA and 40" nBA. Similar terpolyner latices were prepared from acrylates (2) and (3) (Scheme III). Another terpolymer latex made from (3), vinyl acetate, and 2-ethylhexyl acrylate contained 547 solids. Tliese latices and their compositions are summarized in the Table 1 and a sample experimental procedure is given in the experimental section. 

Table III. Low-Angle Light-Scattering and Intrinsic Viscosity Data for NaAMPS-AMPDAC-AM Terpolymers ...

Effects of Ionic Strength. Figure 13 illustrates the effect of NaCl concentration on intrinsic viscosity for each terpolymer. Of course, this experiment should demonstrate only the effects of added electrolyte on individual chain contraction or expansion. The chains with sufficient monomer pairs exhibit increases in viscosity as expected with addition of NaCl. The best chain expansion is seen for the 5-5 sample, which is rapidly solvated with increasing ionic strength. The 5-10 sample shows some typical polyelectrolyte behavior because it has an excess of macroanions at pH 7. 

Figure 14. Intrinsic viscosity versus NaCl concentration for the ADASAM series of terpolymers at 30°C and a shear rate of 1.75 sec . ...

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