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Associative behavior of polyimide/cyclohexanone solutions.

ABSTRACT: Our previous work has demonstrated that soluble polyimide with relatively weak interaction can be transformed from neutral polymer to associative polymer by increasing molecular weight. Thus, it is necessary to find another way to vary the relatively weak interaction strength, i.e. variation of solvent quality. Herein, viscoelastic behaviors are examined for 2,2-bis(3,4-dicarboxy-phenyl) hexafluoropropane dianhydride (6FDA)-2,2'-bis(trifluoromethyl)-4,4'-diam (TFDB) polyimide (PI), with a relatively low molecular weight (M _w) of 88 000 g mol^-1, dissolved in cyclohexanone (CYC). The scaling relationship between viscosity (η ₀-η _s) and volume fraction is in good agreement with the associative polymer theory proposed by Rubinstein and Semenov. Oscillatory rheological results indicate that the PI solution tends to become a gel with increased volume fraction. The synchrotron radiation small-angle X-ray scattering results imply the existence of dense aggregates in the concentrated PI/CYC solutions. Shear thickening and thinning behaviors are observed in the solutions, and the shear thickening behavior of polyimide solution has not been reported in literature. Their mechanisms are studied by conducting dynamic and steady rheological experiments. Thus, enhancing the relatively weak interaction strength can also make the low M _w polyimide show associative polymer behavior. This work can help us to gain deep insight into polyimide solution properties from dilute to semidilute entangled solutions, and will guide the preparation of polyimide solutions for different processing.

SUBMITTER: Chen H

PROVIDER: S-EPMC9070761 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Associative behavior of polyimide/cyclohexanone solutions.

Chen Hongxiang H Liu Wei W Hong Mei M Zhang Ensong E Dai Xuemin X Chen Quan Q Yang Wenke W Xue Yanhu Y Qiu Xuepeng X Ji Xiangling X

RSC advances 20190801 47

Our previous work has demonstrated that soluble polyimide with relatively weak interaction can be transformed from neutral polymer to associative polymer by increasing molecular weight. Thus, it is necessary to find another way to vary the relatively weak interaction strength, <i>i.e.</i> variation of solvent quality. Herein, viscoelastic behaviors are examined for 2,2-bis(3,4-dicarboxy-phenyl) hexafluoropropane dianhydride (6FDA)-2,2'-bis(trifluoromethyl)-4,4'-diam (TFDB) polyimide (PI), with a ...[more]

PMID: 35529184

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Project description:Precise, area-specific connectivity of interhemispheric callosal projection neurons (CPN) in the cerebral cortex is critical for sensory, associative, and behavioral functions. CPN circuitry, which connects and integrates the two cerebral hemispheres via the corpus callosum, is centrally implicated in autism spectrum disorder (ASD) and intellectual disability (ID). Though transcriptional controls regulating CPN subtype and areal development have progressively become partially understood, downstream subcellular mechanisms and molecular machinery that implement precise and diverse CPN circuitry is essentially unknown. Here, we identify that the highly penetrant ASD/ID risk gene Bcl11a/Ctip1 is critical developmentally for appropriate and precise areal targeting of CPN associative projections, and that its deletion both strikingly reshapes these projections, and causes dramatic disruption to circuit-specific subcellular growth cone (GC) molecular machinery and social behavior and cognition in mice. CPN-specific embryonic deletion of Bcl11a causes loss of correct homotopic targeting in the contralateral cortex, re-routes a substantial proportion of their axonal projections through the evolutionarily older anterior commissure, and induces strikingly aberrant, but specific and precise, projections to the basolateral amygdala in adult mice. Importantly, bilateral deletion of Bcl11a from CPN alone results in abnormal social behavior and working memory. Mechanistically, we identify dysregulation of the CPN axonal GC-localized transcriptome in Bcl11a nulls, due to either aberrant transcription or trafficking of individual transcripts. These molecular mis-localizations disrupt axon guidance and CPN-specific associative circuitry formation, causing disease-related behavior. Together, this work identifies critical functions for Bcl11a in CPN axonal connectivity, development of functional associative-social circuitry, regulation of subtype-specific subcellular molecular machinery in vivo, revealing novel GC-localized transcripts that regulate precise axonal targeting and circuit formation. These results elucidate development and ASD/ID disease-related circuit disruption of CPN, and the importance of understanding circuit-specific subcellular– e.g. soma vs. GC– localization of RNA and protein molecular machinery by neurons.

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Associative behavior of polyimide/cyclohexanone solutions.

Publications

Associative behavior of polyimide/cyclohexanone solutions.

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