Dynamics of (micro)phase separation during fast, bulk copolymerization: some synchrotron SAXS experiments

Ryan, Anthony J.; Willkomm, Wayne R.; Bergstrom, T. B.; Macosko, Christopher W.; Koberstein, Jeffrey T.; Yu, Chung Chien; Russell, Thomas P.

doi:10.1021/ma00010a038

Cited by 73 publications

(45 citation statements)

References 8 publications

(9 reference statements)

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“…Among these are a differential scanning calorimeter [2], a Fourier transform infrared spectrometer [3], reaction injection moulding [4], high temperature cells and high pressure cells [S]. A fast temperature jump instrument, enabling the replication of conditions when polymers are injected into a cold mould, is under development.…”

Section: Small and Wide Angle X-ray Scatteringmentioning

confidence: 99%

Structure development studies during materials processing

Bras

Derbyshire

Bouwstra

et al. 1995

Nuclear Instruments and Methods in Physics Research Section B:

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Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractIn the study of materials processing and structural development it has been necessary to develop sample environments for use with X-ray diffraction experiments. Feasibility study results are shown with examples of real time growth of glass ceramics and the formation of zeolites from silicate precursor gels. A further example is shown where the combination of scattering techniques together with a complicated sample environment could play an important role in the medically important problem of transdermal drug delivery.

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Section: Small and Wide Angle X-ray Scatteringmentioning

confidence: 99%

Structure development studies during materials processing

Bras

Derbyshire

Bouwstra

et al. 1995

Nuclear Instruments and Methods in Physics Research Section B:

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“…Due to the thermodynamical dissimilarity, the shape memory polyurethanes will separate into hard‐segment and soft‐segment microphases, which play the roles of fixed phase and reversible network chains for the shape memory effect, respectively 4, 16. Many attempts have been made to elucidate the relationship between the structure and shape memory effect of the polyurethanes 14, 15, 20–25. The morphology of phase separation, phase composition, microdomain sizes, phase distribution, and so on were investigated to optimize the molecular design and explore applications of shape memory polyurethanes.…”

Section: Introductionmentioning

confidence: 99%

Shape memory properties of polycaprolactone‐based polyurethanes prepared by reactive extrusion

Weng

Xia

Chen

et al. 2012

J of Applied Polymer Sci

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The shape memory properties of polycaprolactone-based polyurethanes (PCLUs) synthesized via a novel route of reactive extrusion were investigated in terms of the deformation amplitude, temperature, and rate by differential scanning calorimetry (DSC), dynamic mechanical analyzer, and polarized optical microscopy (POM). DSC analysis shows that the crystalline melting temperature and crystallinity of PCLU increased monotonically with increasing the average polymerization degree ðDPnÞ of poly(e-caprolactone) (PCL) block. The retract force increased with increasing the temperature and reached the maximum (6-7 MPa) within 45-55 C. Furthermore, a modified model with two recovery stages was postulated to elucidate the shape memory process, which is visually presented by POM analysis. The two stages of tensile and compressive recovery are distinguished by the inflexion temperature, within 43-48 C and 64-66 C, respectively. The shape fixity is about 60-70% and can be improved to 100% by choosing proper deformation temperature. The tensile deformation recovery ratio was 80-98% due to the water absorption, whereas the compressive deformation recovery ratio was almost 100%. Besides, recovery tests show that the lowest recovery temperature ranged from 24 to 47 C was influenced by the deformation temperature, rate and the PCL block ðDPnÞ. Thus, the shape memory properties can be adjusted according to different purposes. INTRODUCTIONShape memory polymers, as novel smart materials, have attracted extensive interest 1-16 for their potential promising applications including biomaterials, 1,17 actuators, 5 sensors, 18 and smart textile. 19 In general, the shape memory effect was realized by the cooperation of the chemical or physical cross links and the reversible network chains, which can play the roles of fixed phase and molecular switch, 4,12,16 respectively. The cross links are employed in the course of shape memorization to memorize the original shape. Although the reversible network chains are designed to have a thermal transition at certain temperature, which can be either T g (the reversible network chains are amorphous) or T m (the reversible network chains are crystalline). The reversible network chains are flexible, and therefore the polymers can develop large deformation above the transition temperature. In contrast, they are frozen to lose mobility, and thus the polymers can fixed in a temporary shape below the transition temperature. Shape memory polyurethanes have been an important category in the shape memory polymer family because certain segmented polyurethanes were found to exhibit shape memory effect. 14,15,17 Due to the thermodynamical dissimilarity, the shape memory polyurethanes will separate into hard-segment and soft-segment microphases, which play the roles of fixed phase and reversible network chains for the shape memory effect, respectively. 4,16 Many attempts have been made to elucidate the relationship between the structure and shape memory effect of the polyurethanes. 14,15,[20][21][22][23][24][25] The...

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“…[6][7][8][9][10] The microphase separation of PUs is greatly influenced by the miscibility of the starting compounds, the structure and the molar mass distribution of the segments, the average block lengths, and the ratio of hard to soft segments. 11 Many methods, for example, polarized optical microscope (POM), scanning electron microscope (SEM), dynamic mechanical analysis (DMA), small angle X-ray scattering (SAXS), [12][13][14][15][16] atomic force microscopy (AFM), 11,17 differential scanning calorimetry (DSC), 18 Fourier transform infrared spectra (FTIR) 19 and nuclear magnetic resonance (NMR) 20 etc., have been used to probe the microphase separation. Since the microphase separation and the phase morphology have an important influence on the ultimate properties of the PU copolymers, it is desirable to have a control on the microphase separation in PUs.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, phase behavior, and simulated in vitro degradation of novel HTPB-b-PEG polyurethane copolymers

Luo

Yan

2011

Macromol. Res.

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Two types of polyurethanes with alternating and random block architectures, hydroxyl-terminated liquid polybutadiene and poly(ethylene glycol) block copolymers (HTPB-alt-PEG and HTPB-co-PEG), were synthesized using a coupling reaction route between the hydroxyl groups and the isocyanate groups. The chemical and crystal structures were characterized using Fourier transform-infrared spectroscopy (FTIR) and X-ray diffraction, while phase behavior was examined using scanning electron microscopy (SEM) and differential scanning calorimetry. The biodegradation in a simulated human body fluid was investigated through mass loss, SEM, and FTIR. The experimental results indicated that all of the polyurethane samples bore the microphase separation structure, and the separation degree depended on the sequence structure and molecular weight (MW) of PEG and further affected their in vitro degradation. The driving force was related to the restricted movement of the molecular segments, the crystallization of the soft/hard phases, and/or the hydrogen bonding interactions between the hard segments. The surface morphological change of the degraded samples further demonstrated that the degradation became serious as the PEG MW increased and that the random block copolymers decomposed more easily than the alternating copolymers. The block polymer materials are expected to be incorporated into specific applications in related biomedical fields.

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Dynamics of (micro)phase separation during fast, bulk copolymerization: some synchrotron SAXS experiments

Cited by 73 publications

References 8 publications

Structure development studies during materials processing

Structure development studies during materials processing

Shape memory properties of polycaprolactone‐based polyurethanes prepared by reactive extrusion

Synthesis, phase behavior, and simulated in vitro degradation of novel HTPB-b-PEG polyurethane copolymers

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