Chain Stiffness of Copolycarbonates Containing a Spiro Linkage

The relaxation behavior of substituted bisphenol-A polycarbonates is investigated in the glassy state by mechanical spectroscopy. Conventional bisphenol-A polycarbonate (BA-PC) is compared with polycarbonates based on 1,1‘-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (TMC-PC) and 1,1‘-spiro[bis(3,3-dimethyl-6-hydroxyindane)] (SBI-PC) and random copolymers of the latter with bisphenol-A. In SBI-PC the phenyl flip is not just hindered but completely locked due to the chemical bridge via the spiro linkage. Despite the impossibility of phenyl motion, the γ-relaxation is observed for SBI-PC at roughly the same temperature as for the other two polycarbonates. This is real proof that the phenyl motion is not required for the typical γ-relaxation of polycarbonate at low temperature. Consequently, the polymer chain can get its mobility only from the flexibility of the carbonate linkage. It was also found that the width of the γ-relaxation peak in the SBI copolycarbonates decreases systematically with increasing spiro content. This means that in the rather broad peak in BA-PC there is a contribution of a second damping mechanism at the higher temperature side which is affected by the spiro linkage. That damping contribution is therefore ascribed to the phenyl motion. This also explains why the γ-relaxation of polycarbonates with ortho-substituted phenyls occurs at much higher temperatures. There the carbonate motion couples to the phenyl motion due to sterical hindrance, which is not the case in SBI-PC.

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“…SBI-PC and copolymers of various compositions were synthesized in our laboratory as described previously …”

Section: Methodsmentioning

confidence: 99%

On the Secondary Relaxation of Substituted Bis-A Polycarbonates

Wimberger-Friedl

Schoo

1996

Macromolecules

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“…At the moment that stress is removed, γ R is defined to be zero. For samples in which the steady-state creep compliance is time-dependent, only the elastic part of the compliance will contribute to the recoverable compliance, Creep testing at very low stress values (within the linear viscoelastic limit) can be used to determine the zero-shear viscosity of liquids, compare relative length or branching of polymer chains, − and infer other important molecular information about a polymeric material, just as any other linear rheological function ( G ( t ), etc.). Creep testing, however, is typically most relevant and easiest to utilize for measuring the long-time relaxation of viscoelastic liquids.…”

Section: Network Mechanics and Dynamicsmentioning

confidence: 99%

Molecular Characterization of Polymer Networks

et al. 2021

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Polymer networks are complex systems consisting of molecular components. Whereas the properties of the individual components are typically well understood by most chemists, translating that chemical insight into polymer networks themselves is limited by the statistical and poorly defined nature of network structures. As a result, it is challenging, if not currently impossible, to extrapolate from the molecular behavior of components to the full range of performance and properties of the entire polymer network. Polymer networks therefore present an unrealized, important, and interdisciplinary opportunity to exert molecular-level, chemical control on material macroscopic properties. A barrier to sophisticated molecular approaches to polymer networks is that the techniques for characterizing the molecular structure of networks are often unfamiliar to many scientists. Here, we present a critical overview of the current characterization techniques available to understand the relation between the molecular properties and the resulting performance and behavior of polymer networks, in the absence of added fillers. We highlight the methods available to characterize the chemistry and molecular-level properties of individual polymer strands and junctions, the gelation process by which strands form networks, the structure of the resulting network, and the dynamics and mechanics of the final material. The purpose is not to serve as a detailed manual for conducting these measurements but rather to unify the underlying principles, point out remaining challenges, and provide a concise overview by which chemists can plan characterization strategies that suit their research objectives. Because polymer networks cannot often be sufficiently characterized with a single method, strategic combinations of multiple techniques are typically required for their molecular characterization.

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“…The inverse, obtaining stiffer polymers starting from flexible ones, was described by Wimberger‐Friedl et al10 They introduced spiro linkages in the main chain of a polycarbonate and M̄ e was increased by a factor of 10.…”

Section: Introductionmentioning

confidence: 99%

Flexibilized styrene-N-substituted maleimide copolymers. I. Multiblock copolymers prepared from styrene-maleimide telechelics and polytetrahydrofuran

Teerenstra¹,

Suwier²,

Mele

et al. 2000

J. Polym. Sci. A Polym. Chem.

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Telechelic copolymers of styrene and different N‐substituted‐maleimides (SMIs) with a molecular weight of 2000–8000 g/mol were synthesized using the starved‐feed‐reactor technique and were nearly bifunctional when the monomer feed had a high styrene concentration. The COOH‐terminated rigid SMI blocks were polycondensated with OH‐terminated poly(tetrahydrofuran) (PTHF) blocks, with a molecular weight of 250–1000 g/mol, which are the flexible parts in the generated homogeneous multiblock copolymer. The entanglement density, which is closely related to the toughness of materials, increased in these flexible SMI copolymers (νe = 5.2 · 1025 m−3) compared to the unflexibilized ones (νe = 2.4 · 1025 m−3). The glass transition temperature of these flexibilized, single‐phase multiblock copolymers was still high enough to qualify them as engineering plastics. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3550–3557, 2000

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Chain Stiffness of Copolycarbonates Containing a Spiro Linkage

Cited by 15 publications

References 16 publications

On the Secondary Relaxation of Substituted Bis-A Polycarbonates

On the Secondary Relaxation of Substituted Bis-A Polycarbonates

Molecular Characterization of Polymer Networks

Flexibilized styrene-N-substituted maleimide copolymers. I. Multiblock copolymers prepared from styrene-maleimide telechelics and polytetrahydrofuran

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