Microphase Separation of Bulk and Ultrathin Films of Polyurethane Elastomers

2008 ◽  
Vol 267 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Mutsuhisa Furukawa ◽  
Ken Kojio ◽  
So Kugumiya ◽  
Yusuke Uchiba ◽  
Yoshitaka Mitsui
Keyword(s):  
Ultrathin Films ◽  
Microphase Separation ◽  
Polyurethane Elastomers

scholarly journals Impact of Macrodiols on the Morphological Behavior of H12MDI/HDO-Based Polyurethane Elastomer

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2060
Author(s):  
Shazia Naheed ◽  
Mohammad Zuber ◽  
Mahwish Salman ◽  
Nasir Rasool ◽  
Zumaira Siddique ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Chain Length ◽  
Microphase Separation ◽  
Soft Segment ◽  
Group Identification ◽  
Degree Of Crystallinity ◽  
Polyurethane Elastomers ◽  
Hard Segments ◽  
Morphological Behavior

In this study, we evaluated the morphological behavior of polyurethane elastomers (PUEs) by modifying the soft segment chain length. This was achieved by increasing the soft segment molecular weight (Mn = 400–4000 gmol−1). In this regard, polycaprolactone diol (PCL) was selected as the soft segment, and 4,4′-cyclohexamethylene diisocyanate (H12MDI) and 1,6-hexanediol (HDO) were chosen as the hard segments. The films were prepared by curing polymer on Teflon surfaces. Fourier transform infrared spectroscopy (FTIR) was utilized for functional group identification in the prepared elastomers. FTIR peaks indicated the disappearance of −NCO and −OH groups and the formation of urethane (NHCOO) groups. The morphological behavior of the synthesized polymer samples was also elucidated using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The AFM and SEM results indicated that the extent of microphase separation was enhanced by an increase in the molecular weight of PCL. The phase separation and degree of crystallinity of the soft and hard segments were described using X-ray diffraction (XRD). It was observed that the degree of crystallinity of the synthesized polymers increased with an increase in the soft segment’s chain length. To evaluate hydrophilicity/hydrophobicity, the contact angle was measured. A gradual increase in the contact angle with distilled water and diiodomethane (38.6°–54.9°) test liquids was observed. Moreover, the decrease in surface energy (46.95–24.45 mN/m) was also found to be inconsistent by increasing the molecular weight of polyols.

Coupling of Microphase Separation and Dewetting in Weakly Segregated Diblock Co-polymer Ultrathin Films

Langmuir ◽  
2011 ◽  
Vol 27 (19) ◽  
pp. 11973-11980 ◽  
Author(s):  
Derong Yan ◽  
Haiying Huang ◽  
Tianbai He ◽  
Fajun Zhang
Keyword(s):  
Ultrathin Films ◽  
Microphase Separation

Synthesis and Characterization of Novel Segmented Castable Polyurethanes Based on 2,4-TDI and 3,5-DMTDA

2010 ◽  
Vol 29-32 ◽  
pp. 675-681 ◽  
Author(s):  
Xiao Dong Chen ◽  
Tie Jun Ma ◽  
Hai Zhang ◽  
Rong Sheng Chen
Keyword(s):  
Microphase Separation ◽  
Dynamic Properties ◽  
Testing Machine ◽  
Toluene Diisocyanate ◽  
Test Results ◽  
Polyurethane Elastomers ◽  
Soft Phase ◽  
Irregular Shapes ◽  
Soft Segments

A series of three castable polyurethane elastomers were prepared from 2,4- toluene diisocyanate (TDI) and 3,5-dimethyl-thioltoluenediamine (DMTDA) chain extender, with polyethylene adipate (PEA), polyoxytetramethylene glycol (PTMG) and polycaprolactone (PCL) soft segments. The polyol molecular weight employed was 2000g/mol. The polyurethane elastomers were characterized by an electronmechanical universal testing machine, a LX-A Shore durometer and a Dynamic Mechanical analyzer (DMA). In addition, fractured surface of the polyurethane elastomers was investigated by a field emission scanning electron microscopy (FE-SEM). The test results showed PCL based elastomer exhibits the excellent tear and stress-strain properties that polyester based elastomers offer, while retaining superior resilience similar to polyether based elastomers. The static and dynamic properties of PCL based elastomer were more suitable for dynamic applications. SEM micrographs of all polyurethane samples indicated the existing of microphase separation structure. Particles of the dispersed phase formed by hard phase and crystalline part of the soft phase grow bigger with increasing crystallinity of the soft segments. The hard domains are irregular shapes and with size of a few micrometers.

Synthesis and thermal and mechanical properties of nonisocyanate poly(ether urethane) thermoplastic elastomers containing dibutylene terephthalate and poly(tetramethylene ether) segments

2020 ◽  
pp. 009524432092856
Author(s):  
Wang Guoliang ◽  
Wang Qian ◽  
Zhao Jingbo ◽  
Zhang Zhiyuan ◽  
Zhang Junying
Keyword(s):  
Mechanical Properties ◽  
Microphase Separation ◽  
Thermoplastic Polyurethane ◽  
Gel Permeation Chromatography ◽  
Thermal Characterization ◽  
Thermoplastic Elastomers ◽  
Thermal And Mechanical Properties ◽  
Reduced Pressure ◽  
Polyurethane Elastomers ◽  
Force Microscopy

Several novel semiaromatic poly(ether urethane) thermoplastic elastomers were synthesized through a nonisocyanate route. The nonisocyanate thermoplastic polyurethane elastomers (NI-TPUEs) were prepared via a transurethane polycondensation of bis(hydroxyethyl) hexanediurethane with bis(4-hydroxybutyl) terephthalate and poly(tetramethylene glycol)s under a reduced pressure of 3 mmHg at 170°C. The NI-TPUEs were fully characterized. The influence of hard segment (HS) contents on thermal and mechanical properties was studied. Gel permeation chromatography characterization demonstrated that high molecular weight of NI-TPUEs was obtained. Wide-angle X-ray scattering and thermal characterization verified that NI-TPUEs were crystallizable and had a relatively high melting point. Atomic force microscopy exhibited microphase separation between the crystallized HSs and amorphous phases. High content of HSs and flexible poly(tetramethylene ether) soft segments leads to good crystallization, excellent mechanical property, and good resilience of NI-TPUEs.

Use of new hydroxytelechelic cis-1,4-polyisoprene (HTPI) in the synthesis of polyurethanes (PUs): Influence of isocyanate and chain extender nature and their equivalent ratios on the mechanical and thermal properties of PUs

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Nasreddine Kébir ◽  
Irène Campistron ◽  
Albert Laguerre ◽  
Jean-François Pilard ◽  
Claude Bunel ◽  
...  
Keyword(s):  
Weight Loss ◽  
Microphase Separation ◽  
Thermoplastic Elastomers ◽  
Chain Extender ◽  
Mechanical And Thermal Properties ◽  
Polyurethane Elastomers ◽  
Linear Relationships ◽  
Chain Extenders ◽  
Materials Behavior

AbstractNew segmented polyurethanes (thermoplastic-elastomers) based on previously described hydroxytelechelic cis-1,4-polyisoprene (HTPI), miscellaneous isocyanates and chain extenders at various equivalent ratios were prepared by the classical one-shot method. The influence of the nature of isocyanate and chain extender, as well as their equivalent ratios, on the mechanical and thermal materials behavior was investigated. Thus, a comparative assessment of material properties was performed. Microphase separation of hard and soft segments was observed by DMTA, DSC and AFM. Moreover, according to Thermogravimetric Analysis (TGA), linear relationships depending on the isocyanate and chain extender nature were found between the weight loss (%) and the percentages of hard segments. A classification of thermal stability in terms of weight loss was established. With the aim of a thermo-mechanical comparative study, polyurethane elastomers based on HTPI and isocyanates without chain extender, were also synthesized.

Morphological studies of linear (AB)n multiblock copolymers and their blends

1992 ◽  
Vol 50 (1) ◽  
pp. 384-385
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Electron Microscopy ◽  
Microphase Separation ◽  
Multiblock Copolymers ◽  
First Order ◽  
Morphological Studies ◽  
Transmission Electron ◽  
First Order Phase Transition ◽  
Covalently Bonded ◽  
Total Molecular Weight ◽  
First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

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