Ideal Copolymers and the Second-Order Transitions of Synthetic Rubbers. I. Noncrystalline Copolymers

Abstract

Theoretical and practical evidence is put forward to show that copolymers can be treated like solutions of small molecules in the interpretation of packing phenomena, and that ideal volume-additivity of the repeating units in copolymers is frequently realized. On this basis equations are derived for predicting θ, the second-order transition temperature, of binary copolymers from the two second-order transition temperatures of the pure polymers and their coefficients of expansion in the glassy and rubbery states. Previous mechanistic theories of the second-order transition temperature of such copolymers are thus superseded by a general reduction of the problem to the mechanism of thermal expansion. Practical applications to the choice of monomers in producing synthetic rubbers are outlined, and attention is drawn to the importance of second-order transitions in kinetic measurements on the reactions of polymers.

Drug–Polymer Solubility and Miscibility: Stability Consideration and Practical Challenges in Amorphous Solid Dispersion Development

“…Many times T g of a binary solid dispersion can also be estimated with reasonable accuracy by weight average theories like Fox or Gordon-Taylor equations with small positive or negative deviations due to drug-polymer interactions. 24,27,28 It is generally recognized that T g represents a kinetic boundary of molecular mobility. Here we assume that the width (temperature range) of this boundary is zero and thus to the right of the T g curve in Figure 1 is the equilibrium liquid where structural relaxation occurs rapidly and solubility and miscibility can be measured at equilibrium.…”

Flocculated Amorphous Nanoparticles for Highly Supersaturated Solutions

“…4. According to the Gordon Taylor equation (59,60), the fraction of high T g material may be determined to achieve a reasonable composite T g . Also, removal of excess polymer (including low T g material) in the final powder by filtration is beneficial for the storage stability of amorphous nanoparticles.…”

Influence of Different Polymers on the Crystallization Tendency of Molecularly Dispersed Amorphous Felodipine

“…The constant K is calculated from the ratio of the density of each component (r) and the T g of the two components. 24,25…”