Conformationally restricted linear polyurethanes from acetalized sugar‐based monomers

Abstract

Linear polyurethanes based on sugar monomers having D-gluco, galacto, and D-manno configurations and their secondary hydroxyl groups protected as bicyclic acetals, have been prepared by polyaddition reaction of these diol monomers to hexamethylene diisocyanate (HMDI) and 4,4 0 -methylenebis(phenyl isocyanate) (MDI). The new polyurethanes seem to be amorphous materials, except that obtained from 2,3:4,5-di-O-methylene-galactitol and HMDI. Weight-average molecular weights, determined by GPC, were in the range 16,000-115,200. TGA analyses indicated that the thermal stability of these bicyclic polyurethanes is comparable to those based on the isosorbide; both the onset and the maximum rate decomposition temperatures increased significantly with respect to the polyur-ethanes based on acyclic sugar monomers. The presence of the acetalized alditol units in the polyurethanes also increased the T g s as compared with their acyclic analogs. Deacetalization of the polyurethanes containing di-O-isopropylidene-D-mannitol units yielded the polyhydroxylated polymers in good yields, without apparent degradation of the polymer chain. These hydroxylated polymers showed an enhanced hydrophilicity and degradability and lower T g s and thermal stability than their parent acetalized polyurethanes. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: [4638][4639][4640][4641][4642][4643][4644][4645][4646] 2012

Synthesis of high‐performance polyurethanes with rigid 5‐6‐5‐fused ring system in the main chain from naturally occurring myo‐inositol

“…Furthermore, these T g values were higher than those reported for the polyurethanes with some rigid components derived from naturally occurring compounds: For example, the reported T g s of the polyurethanes obtained from isosorbide by its polyaddition with HMDI, MDI, and TDI were 110, 187, and 136 °C, respectively . Another comparative example is the polyurethanes obtained from a bisketal of d ‐mannitol . The polyaddition of this highly rigid monomer with HMDI and MDI gave the corresponding polyurethanes that exhibited glass transition at 93 and 161 °C, respectively.…”

“…1,4:3,6‐Dianhydrohexitols including isosorbide and their derivatives are such a class of bifunctional monomers derived from monosaccharides . Bisketals of sugars with bicyclic structures such as those of mannitol are also a class of rigid monomers of which utilization for synthesizing several polycondensates exhibiting excellent thermal properties has been demonstrated …”

Fully biobased polyester polyols derived from renewable resources toward preparation of polyurethane and their application for coatings

“…Bifunctionality of isosorbide enables it to be function as a diol, that is, monomer, and makes it suitable for utilization in the synthesis of several polymeric resins like polyester, polyether, polycarbonate, and so forth by undergoing condensation or addition polymerizations . The presence of cyclic rings in isosorbide improves thermal stability of the resultant polymers . Another ingredient utilized in the present invention is dimer acid, which can be synthesized either from oleic acid or in combination with linoleic acid due to the presence of reactive carboxylic groups and functioning as a monomer moiety in the preparation of polymeric resins .…”

Rigid diol bearing 6‐6‐6 fused ring system derived from naturally occurring myo‐inositol and its polyaddition with diisocyanates

“…The rigidity of the repeating units enhances the mechanical strength and thermal stability of the polymers. Another interesting family of renewable diols is the diacetals of sugars such as mannitol . Because they also have rigid bicyclic structures, the corresponding polymers exhibit excellent thermal properties.…”