Study of negative substitution and monomer self‐condensation effects on molar mass and structural characteristics of hyperbranched polyesters originating from a high‐functionality core

Emamikia, Mohammad; Barikani, Mehdi; Bakhshandeh, G. R.

doi:10.1002/pi.4820

Cited by 2 publications

(1 citation statement)

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“…Moreover, positive or negative substitution effects taking place during polyaddition and described in a number of experimental papers [44][45][46][47] would significantly affect both the MW and the structural characteristics of the resulting polymers. The manifestation of a positive substitution effect, e.g., in the Friedel-Crafts aromatic substitution reaction of AB 2 , leads to the production of fully branched HBPs [38].…”

Section: Introductionmentioning

confidence: 99%

A Theoretical Investigation of the Polyaddition of an AB2+A2+B4 Monomer Mixture

Karpov,

Iakunkov,

Chernyaev

et al. 2024

Polymers

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Hyperbranched polymers (HBPs) are widely applied nowadays as functional materials for biomedicine needs, nonlinear optics, organic semiconductors, etc. One of the effective and promising ways to synthesize HBPs is a polyaddition of AB2+A2+B4 monomers that is generated in the A2+CB2, AA′+B3, A2+B′B2, and A2+C2+B3 systems or using other approaches. It is clear that all the foundational features of HBPs that are manufactured by a polyaddition reaction are defined by the component composition of the monomer mixture. For this reason, we have designed a structural kinetic model of AB2+A2+B4 monomer mixture polyaddition which makes it possible to predict the impact of the monomer mixture’s composition on the molecular weight characteristics of hyperbranched polymers (number average (DPn) and weight average (DPw) degree of polymerization), as well as the degree of branching (DB) and gel point (pg). The suggested model also considers the possibility of a positive or negative substitution effect during polyaddition. The change in the macromolecule parameters of HBPs formed by polyaddition of AB2+A2+B4 monomers is described as an infinite system of kinetic equations. The solution for the equation system was found using the method of generating functions. The impact of both the component’s composition and the substitution effect during the polyaddition of AB2+A2+B4 monomers on structural and molecular weight HBP characteristics was investigated. The suggested model is fairly versatile; it makes it possible to describe every possible case of polyaddition with various monomer combinations, such as A2+AB2, AB2+B4, AB2, or A2+B4. The influence of each monomer type on the main characteristics of hyperbranched polymers that are obtained by the polyaddition of AB2+A2+B4 monomers has been investigated. Based on the results obtained, an empirical formula was proposed to estimate the pg = pA during the polyaddition of an AB2+A2+B4 monomer mixture: pg = pA = (−0.53([B]0/[A]0)1/2 + 0.78)υAB2 + (1/3)1/2([B]0/[A]0)1/2, where (1/3)1/2([B]0/[A]0)1/2 is the Flory equation for the A2+B4 polyaddition, [A]0 and [B]0 are the A and B group concentration from A2 and B4, respectively, and υAB2 is the mole fraction of the AB2 monomer in the mixture. The equation obtained allows us to accurately predict the pg value, with an AB2 monomer content of up to 80%.

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Section: Introductionmentioning

confidence: 99%

A Theoretical Investigation of the Polyaddition of an AB2+A2+B4 Monomer Mixture

Karpov,

Iakunkov,

Chernyaev

et al. 2024

Polymers

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Relationship between structure and aromatic solvent permeability of crosslinked polyurethanes based on hyperbranched polyesters

2015

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This work investigates the relationship between structure and aromatic solvent permeability of polyurethanes based on trimethylolpropane (TMP) as a classical crosslinker and self‐made hyperbranched polyesters (HBPEs) as newly developed crosslinking agents. For this purpose three groups of samples were synthesized using toluene diisocyanate, poly(tetramethylene glycol) and different pseudo‐generation numbers of crosslinkers in the variable hard segment content. The results obtained from characterization tests indicate that replacing TMP by HBPE leads to an increase of crosslink density resulting in significant reduction of sorption capacity and conversely leads to an increase of the diffusion coefficient due to the lower glass transition temperature (Tg) of soft segments. In this way, the toluene permeability of hyperbranched polyurethane (HBPU) is considerably lower than that of classical polyurethane. The HBPUs with sufficient amount of hard segment have the lowest solvent uptake and diffusion coefficient leading to optimal barrier performance. By increasing the generation number of HBPE, the crosslink density of HBPU increases, but the crystallinity as well as Tg of soft segments decrease. These two contradictory changing trends of the structural characteristics cause a slight decrease in sorption coefficient of membranes and an increase of diffusivity. Therefore the barrier performance of HBPUs is weakened with increasing generation number of crosslinkers. © 2015 Society of Chemical Industry

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Study of negative substitution and monomer self‐condensation effects on molar mass and structural characteristics of hyperbranched polyesters originating from a high‐functionality core

Abstract: Poly[2,2‐bis(methylol)propionic acid] hyperbranched polymers containing cores with higher functionality are less affected by the negative substitution effect, and consequently their structures have a lower proportion of linear units.

Cited by 2 publications

References 28 publications

A Theoretical Investigation of the Polyaddition of an AB2+A2+B4 Monomer Mixture

A Theoretical Investigation of the Polyaddition of an AB2+A2+B4 Monomer Mixture

Relationship between structure and aromatic solvent permeability of crosslinked polyurethanes based on hyperbranched polyesters

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