In this contribution, we reported the synthesis of organic-inorganic polyurethanes with polyhedral oligomeric silsesquioxane (POSS) in the main chains. Toward this end, 3,13-dihydroxypropyloctaphenyl double-decker silsesquioxane (DDSQ) was synthesized; this POSS diol was used as a chain extender to obtain hybrid polyurethanes with DDSQ in the main chains. By controlling the molar ratio of 3,13-dihydroxypropyloctaphenyl DDSQ to 1,4-butanediol (BDO), organic-inorganic polyurethanes were obtained with a content of DDSQ up to 48 wt%. The results of 1 H nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC) showed that 3,13-dihydroxypropyloctaphenyl, DDSQ, can be successfully used as a chain extender to afford linear organic-inorganic polyurethanes. Differential scanning calorimetry (DSC) showed that the organic-inorganic polyurethanes displayed enhanced glass transition temperatures (T g 's) compared to control polyurethane; the T g 's increased with increasing content of DDSQ in the main chains. Compared to control polyurethane, the organic-inorganic polyurethanes displayed improved thermal stability in terms of thermogravimetric analysis (TGA). With the inclusion of DDSQ in the main chains, the organic-inorganic polyurethanes displayed enhanced surface hydrophobicity.
In this contribution, we report the synthesis of organic–inorganic polyimides with double decker silsesquioxane in the main chains with a novel and well-defined POSS diamine.
A series of novel organic-inorganic copolymers with polyhedral oligomeric silsesquioxane (POSS) in the main chains were synthesized via the copper-catalyzed Huisgen 1,3dipolar cycloaddition polymerization approach. Toward this end, we synthesized 3,13-azidopropyloctaphenyl double-decked silsesquioxane (DDSQ). This difunctional POSS macromer was used to copolymerize with a,x-dialkynyl-terminated oligoethylenes with variable number of ethylene units. The organic-inorganic copolymers were obtained with the mass fraction of POSS up to 79%. Gel permeation chromatography showed that the high-molecular-weight copolymers were successfully obtained in all the cases. Differential scanning calorimetry showed that the amplitude of glass transitions for these copolymers was very feeble, suggesting that the segmental motions responsible for the glass transitions was highly restricted with DDSQ cages in the main chains. Thermogravimetric analysis showed that the organic-inorganic hybrid copolymers displayed extremely high thermal stability. Contact angle measurements showed that these organic-inorganic copolymers are highly hydrophobic and possessed very low surface energy.
3,13-Di(cyclic carbonate) double decker silsesquioxane,
a new difunctional
polyhedral oligomeric silsesquioxane (POSS), was successfully synthesized.
By using this POSS macromer, the organic–inorganic poly(hydroxyl
urethanes) (PHUs) were synthesized with POSS cages in the main chains.
Compared to the neat PHU, the organic–inorganic PHUs displayed
improved thermomechanical properties. The organic–inorganic
PHUs were microphase-separated, and the main-chain POSS cages were
self-assembled into the nanodomains in the size of 10–30 nm.
It was found that the POSS nanodomains acted as the nano-cross-linking
points of physically cross-linked networks. Although the linear organic–inorganic
PHUs were soluble in common organic solvents, they were capable of
displaying the thermomechanical properties similar to cross-linked
PHU elastomers. Owing to the physical cross-linking, the organic–inorganic
PHUs were endowed with shape memory properties. In the meantime, the
organic–inorganic PHUs can be reprocessed at elevated temperature;
the tensile mechanical strength can be recovered up to 90%. The reprocessing
properties resulted from the transcarbamoylation reaction of hydroxyurethane
structural units other than the disintegration of POSS nanodomains
at elevated temperature. The reprocessing properties can be utilized
to program the original shapes of shape memory polymers.
SynopsisThe effect of fiber structure and morphology on the resultant mechanical and low load deformation properties of thermally bonded nonwoven polypropylene fabrics has been studied. Commercially available staple polypropylene fibers varying in linear density and draw ratio (Herculon and Marvess staple fibers) were used in this study. The orientation of these fibers was characterized by birefrigence measurements. Differential scanning calorimetry measurements were made to determine the heat of fusion and melting point of fibers. Experiments confirm that tensile strength and stiffness of the fabrics correlate with this fiber structure. Under the same bonding conditions fabrics made from fibers with low draw ratios show higher tensile strength and stiffness than do fibers with high draw ratios. The mechanical properties of fabrics were found to be greatly affected by the thermal bonding temperature. The tenacity and flexural rigidity of fabrics made from poorly oriented fibers show higher values than those made from highly oriented fibers. The shrinkage of the fabrics was observed to increase with increasing bonding temperature in both machine and cross machine directions. The changes in fabric thickness due to the thermal bonding are considerably lower for poorly oriented fibers.
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