Diacetylene Containing Polyesters and Segmented Polyurethanes with Body Temperature Sensitive Thermochromic Transitions

1993 ◽  
Vol 328 ◽  
Author(s):  
Ken D. Zemach ◽  
M. F. Rubner
Keyword(s):  
Body Temperature ◽  
Soft Segment ◽  
Polymerization Process ◽  
Temperature Sensitive ◽  
Processing Conditions ◽  
Highly Sensitive ◽  
Wide Range ◽  
Soft Segments ◽  
Hard Segments ◽  
Segmented Polyurethanes

ABSTRACTSeveral diacetylene containing polyesters with thermochromic transitions at or around room temperature have been synthesized. Some of these polymers have been shown to be highly sensitive to body temperature, giving rise to either reversible or irreversible thermochromic changes, depending upon both the molecular structure and the processing conditions. By changing the structure and processing conditions, the thermochromic transition can be moved over a wide range of temperatures. Segmented polyurethanes using these diacetylene functionalized polyesters as soft segments and containing diacetylene groups in the hard segments have also been produced. Through a selective polymerization process, it is possible to selectively cross-polymerize the hard segment diacetylene groups or cross-polymerize both the hard and soft segments thereby making it possible to examine the effects of hard and soft segment crosslinking on mechanical properties.

Effect of Block Molecular Weight on the Mechanical Properties of PA1010-b-PEG Segmented Block Copolymers

2012 ◽  
Vol 512-515 ◽  
pp. 2127-2130
Author(s):  
Li Huo ◽  
Cai Xia Dong
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Block Copolymers ◽  
Microphase Separation ◽  
Soft Segment ◽  
Mechanical Measurements ◽  
Wide Range ◽  
Hard Block ◽  
Higher Temperature ◽  
Hard Segments

The mechanical properties were investigated of a series of PA-PEG thermalplastic elastomer based on PA1010 and polytetramethylene glycol (PEG) with varying hard and soft segment content. Dynamic mechanical measurements of these polymers have carried out over a wide range of temperatures. The block copolymers exhibit three peaks, designated as α, β and γ in the tanδ-temperature curve. The α transition shifts to higher temperature with increasing hard block molecular weight. However, at a constant hard molecular weight, the α transition shifts to higher temperature and the damping increases on increasing the soft segment molecular weight. DMA results show that the block copolymers exhibit a microphase separation structure and both soft and hard segments were found to be crystallizable. The degree of phase separation increases with increasing hard block molecular weight.

Polyurethanes with aggregation-enhanced emission characteristics: preparation and properties

2017 ◽  
Vol 196 ◽  
pp. 43-54 ◽  
Author(s):  
Kun Wang ◽  
Jiping Yang ◽  
Chen Gong ◽  
Hao Lu
Keyword(s):  
Fluorescence Intensity ◽  
Soft Segment ◽  
Fluorescence Emission ◽  
Water Mixture ◽  
Stimuli Responsive ◽  
Scanning Calorimetry ◽  
Responsive Materials ◽  
Molar Ratios ◽  
Soft Segments ◽  
Hard Segments

An amino-terminated poly(propylene glycol)-modified tetraaryl-buta-1,3-diene derivative (TABDAA) was introduced to synthesize polyurethanes with different ratios of soft/hard segments. A mixture of TABDAA and poly(tetrahydrofuran) 1000 as the soft segments was reacted with 4,4-diphenylmethane diisocyanate and 1,4-butanediol as the hard segments in molar ratios of 1 : 2 : 1, 2 : 3 : 1, and 3 : 4 : 1 to give the desired polyurethanes named TMPU-211, TMPU-321 and TMPU-431, respectively. The three polyurethanes exhibited different aggregation-enhanced emission (AEE) behaviors because of their different soft/hard segment ratios. The polyurethanes with a higher soft segment content tended to form bigger particles in a DMF/water mixture solution, thus causing a sharper increase in their fluorescence intensity. In addition, the polyurethane films exhibited different fluorescence intensities after different heat treatments. After a quenching treatment of the soft segments in the polyurethane films, the fluorescence intensity dropped greatly. When these quenched polyurethane films were thermally annealed at 60 °C for 24 hours, their fluorescence intensity exceeded the initial intensity of the as-prepared films. Differential scanning calorimetry results showed that the polyurethane films in the quenched condition did not present the endothermal melting peak of the soft segments, and the melting peaks appeared again after thermal annealing. AFM experiments showed that an ordered arrangement was achieved after the heat treatment of these AEE polyurethane films. These results demonstrated that the polymer structure had a significant effect on the AEE properties of the polyurethane films, and more importantly, it is of great significance in improving the fluorescence emission of the AEE polymers and also for their potential application in fluorescent probes, stimuli-responsive materials, PLED devices and so on.

Study on the Influences of Domain Structure of Hydrophilic Polyurethane with Partially Crystalline on its Moisture Permeability

2011 ◽  
Vol 233-235 ◽  
pp. 281-287
Author(s):  
Heng Quan ◽  
Zhen Ya Gu
Keyword(s):  
Chemical Structure ◽  
Hard Segment ◽  
Microphase Separation ◽  
Soft Segment ◽  
Moisture Permeability ◽  
Soft Segments ◽  
Separation Degree ◽  
Polyethylene Glycol 1000 ◽  
Segmented Polyurethanes ◽  
Hydrophilic Polyurethane

Multiphase, segmented polyurethanes with mixed soft segment phase were prepared from 4,4’- diphenylmethane diisocyanate (Pure MDI), polybutylene adipate (glycol) 2000 (PBA2000) and polyethylene glycol 1000 (PEG1000) with 1,4-butanediol (BDO) as the chain extender. Further more, the relationships between domain separation structure, crystallizability of soft segment and moisture permeability, hydrophilic property, phase inversion temperature (PIT) of the polyurethanes were investigated. The studies show that the chemical structure, concentration of hydrophilic soft monomers and the microphase separation degree of the mixed soft segments from hard segment domain have remarkable effects on the application properties of polyurethane.

Study of the Effect of Soft-Segment Length and Concentration on Properties of Polyetherurethanes. II. The Effect on Mechanical Properties

1985 ◽  
Vol 58 (4) ◽  
pp. 701-712 ◽  
Author(s):  
Zoran S. Petrović ◽  
Jaroslava Budinski-Simendić
Keyword(s):  
Mechanical Properties ◽  
Chain Length ◽  
Plastic Flow ◽  
Soft Segment ◽  
Maximum Strength ◽  
Segment Length ◽  
Elongation At Break ◽  
Mechanical Methods ◽  
Soft Segments ◽  
Segmented Polyurethanes

Abstract Three series of segmented polyurethanes with different soft segment lengths and concentrations were examined by TMA, DMA, and mechanical methods. Maximum tensile strengths were obtained when ssc was 40–50%, which was explained by a specific interlocking morphology. No significant effect of soft-segment chain length on maximum strength was found, but higher values were found in the C series when ssc was 60%. Elongation at break increases linearly with ssc but indications that shorter soft segments produce higher extensions was attributed to plastic flow. TMA showed that Tg was independent of ssc in the C and, to a degree, in the B series, while temperature of α-transition in DMA was independent of ssc only in the C series at ssc above 50%.

Polydimethylsiloxane-Based Polyurethanes: Phase-Separated Morphology and In Vitro Oxidative Biostability

2009 ◽  
Vol 62 (8) ◽  
pp. 794 ◽  
Author(s):  
Taeyi Choi ◽  
Jadwiga Weksler ◽  
Ajay Padsalgikar ◽  
Rebeca Hernéndez ◽  
James Runt
Keyword(s):  
Segmented Polyurethane ◽  
Two Phase ◽  
Dimethyl Siloxane ◽  
X Ray Scattering ◽  
Soft Segments ◽  
Hard Segments ◽  
Segmented Polyurethanes ◽  
Methylenediphenyl Diisocyanate ◽  
End Group

Three series of segmented polyurethane block copolymers were synthesized using 4,4′-methylenediphenyl diisocyanate (MDI) and 1,4-butanediol (BDO) or 1,3-bis(4-hydroxybutyl)tetramethyl disiloxane (BHTD) as the hard segments, and soft segments composed of poly(dimethyl siloxane) (PDMS)-based and poly(hexamethylene oxide) (PHMO) macrodiols. Copolymers synthesized with the PDMS macrodiol and PDMS and PHMO macrodiol mixtures consist of three microphases: a PDMS phase, hard domains, and a mixed phase of PHMO (when present), PDMS ether end-group segments and some dissolved hard segments. Degrees of phase separation were characterized using small-angle X-ray scattering by applying a pseudo two-phase model, and the morphology resulting from unlike segment demixing was found to be closely related to the in vitro oxidative biostability of these segmented polyurethanes.

Synthesis and blood compatibilities of novel segmented polyurethanes containing phosphatidylcholine analogous moieties in the main chains and long-chain alkyl groups in the side chains

1999 ◽  
Vol 14 (9) ◽  
pp. 3789-3798 ◽  
Author(s):  
Arata Korematsu ◽  
Yu-Jun Li ◽  
Takayuki Murakami ◽  
Tadao Nakaya
Keyword(s):  
Platelet Adhesion ◽  
Platelet Rich Plasma ◽  
Side Chains ◽  
Alkyl Groups ◽  
Low Degree ◽  
Soft Segments ◽  
Hard Segments ◽  
Segmented Polyurethanes ◽  
Methylenediphenyl Diisocyanate ◽  
Long Chain

New segmented polyurethanes containing phospholipid moieties in the main chains and long-chain alkyl groups in the side chains were synthesized. The soft segments used in this study were poly(butadiene), poly(isoprene), hydrogenated poly(isoprene), and poly(1,6-hexyl-1,2-ethylcarbonate) diol. The hard segments of these polyurethanes were 4,4′-methylenediphenyl diisocyanate, bis[2-(2-hydroxyethyldimethylammonio)ethyl]2-cetyl- 1,3-propanediphosphate, and 1,4-butanediol. The blood compatibilities of the new polymers were evaluated by platelet-rich plasma contact studies and viewed by scanning electron microscopy using medical grade BioSpan® and nonphospholipid polyurethane as references. These new materials have good surfaces in terms of platelet adhesion, and the morphology of adhered platelets undergoes a relatively low degree of variation.

Chain Conformation in Elastomeric Multiblock Copolymers as Measured by Small-Angle Neutron Scattering

1985 ◽  
Vol 58 (5) ◽  
pp. 899-912 ◽  
Author(s):  
Stuart L. Cooper ◽  
John A. Miller
Keyword(s):  
Small Angle ◽  
Hard Segment ◽  
Elevated Temperatures ◽  
Soft Segment ◽  
Random Coil ◽  
Radius Of Gyration ◽  
Soft Phase ◽  
Soft Segments ◽  
Hard Segments ◽  
Increasing Temperature

Abstract Small-angle neutron scattering has been shown to be an effective technique for investigating segment conformation in two-phase multiblock copolymer systems. By choosing the appropriate isotopic compositions, either segment can be investigated, as can the whole chain. The best approach to the experiment is to use a phase-contrast matched sample, one where no interphase scattering occurs. This allows the experiments to be carried out on a single sample, simplifying the experiment, and reducing the beam time requirements. Equations (2) and (3) describe the phase-contrast matched criterion. At room temperature, the polyether soft segments in the polyurethane elastomer-and in the polyether-polyester block copolymers are somewhat extended on the average relative to the bulk oligomer conformation. In the polyether-polyester with a lower hard-segment content, the soft segments are less extended than in the higher ester content material. A distribution of conformations occurs in these materials, with a majority of the soft segments being nearly in a random-coil conformation. A substantial number of segments are fairly taut, leading to an average conformation that is somewhat extended relative to the random coil conformation. The soft-segment radius of gyration in the polyurethane material initially decreases with increasing temperature. As the temperature rises, the retractive force on the taut soft segments increases, thus facilitating the extraction of hard segments from the amorphous hard phase into the soft phase. One would expect that the degree of phase separation would decrease with increasing temperature due to such a mechanism, and in fact this is borne out by small-angle x-ray scattering studies. Above 150°C, an upturn in the soft-segment radius of gyration is observed. Koberstein et al. propose a phase mixing transition around this temperature in polyurethane systems. Such a transition implies a greater compatibility between the hard and soft segment types at elevated temperatures. Thus, a swelling of the soft segments is seen due to favorable interactions with the hard segments located in the soft phase. A schematic diagram of the polyurethane microstructure and chain conformation is presented in Figure 9. The soft-segment radius of gyration in the polyether-polyester materials decreases smoothly with increasing temperature. This is primarily due to a decrease in the number of taut tie molecules present at elevated temperatures due to the rearrangement of the hard crystalline domains. In addition, relaxation of stresses introduced by molding these samples below the hard-segment crystalline melting temperature may contribute to the decrease in the soft-segment Rg.

HVEM and high resolution SEM of polyurethane bulk and surface structure

1988 ◽  
Vol 46 ◽  
pp. 936-937
Author(s):  
S. L. Goodman ◽  
C. Li ◽  
S. L. Cooper ◽  
R. M. Albrecht
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Soft Segment ◽  
Structure Property ◽  
Two Phase ◽  
Near Surface ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Soft Segments ◽  
Hard Segments

Segmented polyurethanes (PUs) are composed of alternating blocks of crystalline or glassy urethane “hard segments” and rubbery “soft segments.” Chemical incompatability between hard segment (HS) and soft segment (SS) blocks produces a two-phase structure, which accounts for the elastomeric properties of these polymer systems. Polyurethanes are prepared with different HS and SS components, and HS:SS ratios, for various applications. Knowledge of the 3D morphology is necessary to understand polyurethane structure-property relationships. Although conventional transmission electron microscopy can image some polyurethanes, high voltage electron microscopy (HVEM) causes less radiation damage and images thicker samples at higher resolution, thus a sample region may be imaged at multiple tilt angles to provide 3D information. High resolution scanning electron microscopy (HR-SEM) provides complementary information, and at low accelerating voltages (1-3 keV), images near surface structures.Polyurethanes were examined with hard segments of methylene diphenylene diisocyanate (MDI) and 2000 MW soft segments of polytetramethylene oxide (PTMO), polybutadiene (PBD) and polydimethysiloxane (PDMS).

scholarly journals PEG-POSS Star Molecules Blended in Polyurethane with Flexible Hard Segments: Morphology and Dynamics

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 99
Author(s):  
Konstantinos N. Raftopoulos ◽  
Edyta Hebda ◽  
Anna Grzybowska ◽  
Panagiotis A. Klonos ◽  
Apostolos Kyritsis ◽  
...  
Keyword(s):  
Glass Transition ◽  
Star Polymer ◽  
Polymerization Process ◽  
Degree Of Crystallinity ◽  
Dielectric Relaxation Spectroscopy ◽  
Scanning Calorimetry ◽  
Similar System ◽  
Soft Phase ◽  
Hard Segments ◽  
Star Molecules

A star polymer with a polyhedral oligomeric silsesquioxanne (POSS) core and poly(ethylene glycol) (PEG) vertex groups is incorporated in a polyurethane with flexible hard segments in-situ during the polymerization process. The blends are studied in terms of morphology, molecular dynamics, and charge mobility. The methods utilized for this purpose are scanning electron and atomic force microscopies (SEM, AFM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and to a larger extent dielectric relaxation spectroscopy (DRS). It is found that POSS reduces the degree of crystallinity of the hard segments. Contrary to what was observed in a similar system with POSS pendent along the main chain, soft phase calorimetric glass transition temperature drops as a result of plasticization, and homogenization of the soft phase by the star molecules. The dynamic glass transition though, remains practically unaffected, and a hypothesis is formed to resolve the discrepancy, based on the assumption of different thermal and dielectric responses of slow and fast modes of the system. A relaxation α′, slower than the bulky segmental α and common in polyurethanes, appears here too. A detailed analysis of dielectric spectra provides some evidence that this relaxation has cooperative character. An additional relaxation g, which is not commonly observed, accompanies the Maxwell Wagner Sillars interfacial polarization process, and has dynamics similar to it. POSS is found to introduce conductivity and possibly alter its mechanism. The study points out that different architectures of incorporation of POSS in polyurethane affect its physical properties by different mechanisms.

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