Values Of Unperturbed Dimensions Research Articles

Water insoluble polyacrylamide—V. Dilute solution properties of poly( N-acryloyl- o-aminobenzoic acid)

A high molecular weight poly( N-acryloyl- o-aminobenzoic acid) has been synthesized by radical polymerization in a mixed solvent medium. The polymer has been fractionated by fractional precipitation and the fractions characterized by viscometry, vapour pressure osmometry and gel permeation chromatography. Mark-Houwink-Kuhn-Sakurada relationships are developed for three solvents. The values of unperturbed dimensions, (〈 R 0 2〉/ M) 0.5, are evaluated by application of two-parameter theories of the excluded volume effect, developed by Fixman, Kurata, Stockmayer and Roig and by Bueche and James and first order perturbation theory. Based on the value of the conformational parameter σ, the polymer is found to behave as a semiflexible polymer in solution as a result of the increased bulk of the lateral group.

Synthesis and solution properties of poly[2-methoxy-4,6-di( p, p′-isopropylidene diphenyloxy)- s-triazine] I

Poly[2-methoxy-4,6-di( p, p′-isopropylidene diphenyloxy)- s-triazine] has been synthesized by interfacial polycondensation of 2-methoxy-4,6-dichloro- s-triazine with bisphenol A. The conditions have been optimized to prepare a sample of both high solubility and molecular weight. The polymer has been fractionated by fractional precipitation and the fractions characterized by viscometry, osmometry and gel permeation chromatography. Mark-Houwink-Kuhn-Sakurada (MHKS) expressions have been developed for three solvents. The values of unperturbed dimensions (<R 2> 0/M) 1 2 , solvent-polymer interaction parameter (B and χ 1) and conformational parameter (σ) have been computed by applying the two-parameter theories of excluded volume developed by Fixman, Kurata, Stockmayer and Roig and by Flory, Fox and Schaefgen.

Polybutene-1. Unperturbed molecular dimensions at different temperatures of isotactic and atactic stereoisomers

By viscosity measurements in θ solvents at various temperatures, values of unperturbed dimensions and of (d ln r 0 2 / dT ) are calculated for isotactic and atactic polybutene-1. (d ln r 0 2 / dT ) values for the two stereoisomers are also calculated by measurements of [η] in a good solvent at various temperatures, according to the theories of Flory-Fox, Kurata-Stockmayer-Roig and Flory-Fisk; the reliability of these theories is estimated. The conclusions are: 1. (1) Both the atactic and isotactic polymer dimensions decrease with increase of temperature, over the range investigated; however, (d ln r 0 2 / dT ) for isotactic polymer is greater than for atactic. 2. (2) The variation of log K θ with T for atactic polybutene cannot be represented by a straight line over a wide range of temperature; it tends to increase in the lower temperature region. A similar behaviour appears for isotactic counterpart. 3. (3) At fairly low temperature (i.e. at room temperature or slightly higher), isotactic polybutene shows larger dimensions than atactic polymer of the same molecular weight. 4. (4) At fairly high temperature (near the melting point of the bulk isotactic polymer), the dimensions of the two stereoisomers are practically the same.