Chain Conformation of Adsorbed Ethylene Random Copolymers

Random copolyesters composed of wholly aromatic monomers such as p-oxybenzoate (B) and 2,6-oxynaphthoate (N) are known to exhibit liquid crystalline characteristics at elevated temperatures and over a broad composition range. Previous studies employing techniques such as X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) have conclusively proven that these thermotropic copolymers can possess a significant crystalline fraction, depending on molecular characteristics and processing history, despite the fact that the copolymer chains possess random intramolecular sequencing. Consequently, the nature of the crystalline structure that develops when these materials are processed in their mesophases and subsequently annealed has recently received considerable attention. A model that has been consistent with all experimental observations involves the Non-Periodic Layer (NPL) crystallite, which occurs when identical monomer sequences enter into register between adjacent chains. The objective of this work is to employ electron microscopy to identify and characterize these crystallites.

Download Full-text

Fluctuation Theory of Random Copolymers

Journal de Physique I ◽

10.1051/jp1:1995131 ◽

1995 ◽

Vol 5 (3) ◽

pp. 365-377 ◽

Cited By ~ 11

Author(s):

Andrey V. Dobrynin ◽

Igor Ya. Erukhimovich

Keyword(s):

Fluctuation Theory ◽

Random Copolymers

Download Full-text

Fluctuation Theory of Charged AB-Random Copolymers

Journal de Physique II ◽

10.1051/jp2:1995179 ◽

1995 ◽

Vol 5 (8) ◽

pp. 1241-1253 ◽

Cited By ~ 3

Author(s):

Andrey V. Dobrynin

Keyword(s):

Fluctuation Theory ◽

Random Copolymers

Download Full-text

Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron-Electron Resonance

10.26434/chemrxiv.10002785 ◽

2019 ◽

Author(s):

Dennis Bücker ◽

Annika Sickinger ◽

Julian D. Ruiz Perez ◽

Manuel Oestringer ◽

Stefan Mecking ◽

...

Keyword(s):

Chain Length ◽

Length Distribution ◽

Catalyst System ◽

Chain Conformation ◽

Controlled Polymerization ◽

Chain Length Distribution ◽

Electron Resonance ◽

Double Electron ◽

The Individual ◽

Double Electron Electron Resonance

Synthetic polymers are mixtures of different length chains, and their chain length and chain conformation is often experimentally characterized by ensemble averages. We demonstrate that Double-Electron-Electron-Resonance (DEER) spectroscopy can reveal the chain length distribution, and chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki-Miyaura Coupling Polymerization (cSMCP). The required spin-labeled chain ends were introduced efficiently via a TEMPO-substituted initiator and chain terminating agent, respectively, with an in situ catalyst system. Individual precise chain length oligomers as reference materials were obtained by a stepwise approach. Chain length distribution, chain conformation and flexibility can also be accessed within poly(fluorene) nanoparticles.

Download Full-text

Mixed matrix membranes with molecular-interaction-driven tunable free volumes for efficient bio-fuel recovery

Journal of Materials Chemistry A ◽

10.1039/c4ta05881j ◽

2015 ◽

Vol 3 (8) ◽

pp. 4510-4521 ◽

Cited By ~ 74

Author(s):

Gongping Liu ◽

Wei-Song Hung ◽

Jie Shen ◽

Qianqian Li ◽

Yun-Hsuan Huang ◽

...

Keyword(s):

Polymer Chain ◽

Molecular Interactions ◽

Molecular Interaction ◽

Chain Conformation ◽

Mixed Matrix Membranes ◽

Mixed Matrix ◽

Polymer Chain Conformation ◽

Matrix Membranes

Molecular interactions were constructed to control polymer chain conformation to fabricate mixed matrix membranes with tunable free volumes, exhibiting simultaneously improved butanol permeability and selectivity.

Download Full-text

Crystallization of Random Metallocene-Catalyzed Propylene-Based Copolymers with Ethylene and 1-Hexene on Rapid Cooling

Polymers ◽

10.3390/polym13132091 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2091

Author(s):

Daniela Mileva ◽

Jingbo Wang ◽

René Androsch ◽

Katalee Jariyavidyanont ◽

Markus Gahleitner ◽

...

Keyword(s):

Mechanical Performance ◽

Metallocene Catalyst ◽

Nucleating Agent ◽

Random Copolymers ◽

Rapid Cooling ◽

Significant Difference ◽

Chip Calorimetry ◽

High Cooling Rates ◽

Fast Scanning Chip Calorimetry

Propylene-based random copolymers with either ethylene or 1-hexene as comonomer, produced using a metallocene catalyst, were studied regarding their crystallization behaviors, with a focus on rapid cooling. To get an impression of processing effects, fast scanning chip calorimetry (FSC) was used in addition to the characterization of the mechanical performance. When comparing the comonomer type and the relation to commercial grades based on Ziegler–Natta-type catalysts, both an interaction with the catalyst-related regio-defects and a significant difference between ethylene and 1-hexene was observed. A soluble-type nucleating agent was found to modify the behavior, but to an increasingly lesser degree at high cooling rates.

Download Full-text