Statistical thermodynamics of mixtures of semirigid macromolecules: chains with rodlike sequences at fixed locations

Matheson, R. R.; Flory, Paul J.

doi:10.1021/ma50005a013

Cited by 157 publications

(61 citation statements)

References 8 publications

(12 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the copolymers studied here, in the extreme case with no rotational restriction at the bipyridyl unit Eqn. 10 becomes = -Kc(M) ô (12) where is the molecular weight of the rodlike PBT chain sequence in the copolymer. If the fraction (1-x) > 0 of the phenylene moieties replaced by bipyridyl units are randomly distributed, then (MR)W m0(2-x)/x, where m0 is the PJ3T repeat unit molecular weieht (n0 = 266).…”

Section: Solutions In Methane Sulfonic Acidmentioning

confidence: 99%

Studies on dilute solution of rodlike macroions: Part 4 - Aggregation with enhanced interchain orientational correlation

Furukawa¹,

Berry²

1985

Pure and Applied Chemistry

View full text Add to dashboard Cite

-Polarized and depolarized absolute intensity light scattering, photon correlation light scattering and viscometry studies are reported on solutions in methane sulfonic acid, MSA, poly(1,4-phenylene-2,6-benzobisthiazole), PBT, and copolymers of PBT containing a bipyridyl moiety in place of some of the phenylene residues. It is found that addition of the potassium salt of MSA to the solutions reduces the second virial coefficient and causes pronounced increase in the depolarized scattering, with accompanying changes in other properties studied. The photon correlation light scattering is analyzed in terms of pseudo-components comprising aggregates with substantial orientational correlation among the rodlike chain elements. This behavior may be in accord with predicted behavior for the phase equilibria for rodlike chains.

show abstract

Section: Solutions In Methane Sulfonic Acidmentioning

confidence: 99%

Studies on dilute solution of rodlike macroions: Part 4 - Aggregation with enhanced interchain orientational correlation

Furukawa¹,

Berry²

1985

Pure and Applied Chemistry

View full text Add to dashboard Cite

show abstract

“…Theory predicts a narrow biphasic region and a single mesophase for a binary system involving a block copolymer and a solvent, provided the length of the flexible block is not too large. 6 The same theory predicts that such a copolymer will form a mesophase at a larger concentration than the corresponding rigid block. However, we observed a smaller critical concentration for the residue of the DMSO extraction than for pure PBA, raising the interesting possibility of a conformational reorganization of the flexible block.…”

Section: Discussionmentioning

confidence: 92%

“…In fact, it has been theoretically predicted 6 that a block copolymer composed of rigid and flexible blocks, or a mixture of such copolymers, can enter the nematic phase. Typical phase diagrams were presented 1 to illustrate this case.…”

mentioning

confidence: 99%

Nematogenic Block Copolymers of Rigid and Flexible Aromatic Units III. Additional Phase Equilibria Studies

Bianchi

Ciferri

Conio

et al. 1988

Polym J

View full text Add to dashboard Cite

ABSTRACT:The mesophase behavior of block copolymers composed of rigid poly(p-benzamide) (PBA) and the flexible polyterephthalamide of p-aminobenzhydrazide (PABH-T) (80: 20, w/w) was investigated using N,N-dimethylacetamide (DMAc)+ 3% LiCI as a solvent. These copolymers include a fraction soluble in dimethyl sulfoxide (DMSO) which was attributed to oligomers and polymers rich in PABH-T. The variation of the volume fraction of the isotropic phase with overall composition within the biphasic gap is more complex than previously observed. As a result, a single anisotropic phase cannot be observed. The flexible component soluble in DMSO is partitioned between the conjugated phases, apparently violating the incompatibility between rigid and flexible polymers in the mesophase. The solubility of these systems is larger than that of the rigid homopolymer. Characterization of the component soluble in DMSO, of the residue, and of the reassembled sample was also performed. The latter shows an incomplete recovery of the properties of the original sample, suggesting labile adducts between rigid and flexible components in the mesophase. Results are discussed in terms of current theories for the liquid crystalline behavior of copolymers.KEY WORDS Block Copolymers/ Aromatic Polyamides / Liquid Crystals/In a previous report 1 we described the phase behavior of a system obtained by polymerizing2 p-aminobenzhydrazide and terephthalic acid in the presence of poly(p-benzamide), PBA. The polymerization yielded a mixture of block copolymer composed of rigid PBA and the more flexible polyterephthalamide of pamino benzhydrazide (PABH-T) sequences, along with some amounts of the flexible and rigid homopolymers. The product resulting from this polymerization exhibited some remarkable properties. It was found that the flexible, PABH-T rich component entered the nematic phase formed above the critical concentration of rigid PBA blocks in N,Ndimethylacetamide (DMAc) containing 3%LiCI. Previous studies 3 • 4 concerning mechanical blends of PBA and PABH-T homopolymers had demonstrated, in accord with theoretical predictions,5 complete exclusion of the flexible homopolymer from the mesophase of the rigid one. Moreover, the solubility of the product of the block polymerization was unusually large. However, when the PABH-T rich component was extracted with dimethyl sulfoxide (DMSO), the solubility of the residue decreased toward the value observed with mechanical blends of the two components.It was suggested that labile adducts formed during the block polymerization simulated some of the properties expected for a block copolymer. In fact, it has been theoretically predicted 6 that a block copolymer composed of rigid and flexible blocks, or a mixture of 83

show abstract

“…These values can then be inserted into Eqs. (5) and ( 6 ) . The calculation of x is considered first.…”

Section: Calculation Of the Free Energies Of Each Pathway Step Afi-i+lmentioning

confidence: 99%

Early assembly pathways of type I collagen

Wallace¹

1992

Biopolymers

View full text Add to dashboard Cite

A method was developed for computing the free energy (delta Fi) of aggregates of type I collagen. The method was based on a treatment of Matheson and Flory describing phase equilibria of rigid rod polymers. It included a polymer-solvent interaction term that depended on near neighbor transfer energies. Extrahelical portions of the molecule were assigned local interaction energies differing from that assigned to the helix. Free energies of reaction for successive steps along assembly pathways (delta Fi-i+1) were computed. When allowance was made for specific pairing between extrahelical and helical domains, the so-called D-staggered (D = 670 A) alignment of molecules was preferred, as opposed to a nonstaggered, or nematic, alignment. Based on delta Fi-i+1 alone, it appeared that 1D-staggered oligomers arise first in assembly, followed later by addition of molecules in 4D alignment. Neither 4D dimers nor 4D-8D trimers were predicted to be major intermediates in assembly. This result is contrary to previous hypotheses. When energies of activation were included in the analysis, the prediction was less certain, and specific circumstances were identified in which 4D dimers and 4D-8D trimers were the earliest aggregated species in assembly.

show abstract

Statistical thermodynamics of mixtures of semirigid macromolecules: chains with rodlike sequences at fixed locations

Cited by 157 publications

References 8 publications

Studies on dilute solution of rodlike macroions: Part 4 - Aggregation with enhanced interchain orientational correlation

Studies on dilute solution of rodlike macroions: Part 4 - Aggregation with enhanced interchain orientational correlation

Nematogenic Block Copolymers of Rigid and Flexible Aromatic Units III. Additional Phase Equilibria Studies

Early assembly pathways of type I collagen

Contact Info

Product

Resources

About