Hydroxylated Linear Polyurethanes Derived from Sugar Alditols

Abstract

A set of linear [m,n]‐type polyurethanes was synthesized by reaction of HDI or MDI with conveniently protected sugar alditols L‐threitol (LTh), L‐arabinitol (LAr) and xylitol (Xy). $\overline M _{\rm n}$ of the resulting polyurethanes ranged between 10 000 and 60 000 with polydispersities around 2. They were thermally stable, showing no decomposition up to temperatures near 300 °C. They all were amorphous polymers with Tg highly dependent on the constitution of the diisocyanate, but scarcely dependent on the structure of the alditol. Hydrogenation of the LThBn‐HDI polyurethane yielded partially debenzylated products with Tg values ranging between 20 and 30 °C. Fully benzylated polyurethanes showed high resistance to hydrolytic degradation, whereas polyurethane with free hydroxyl side groups degraded significantly in saline buffer at pH = 10 and 37 °C.

Synthesis of Functional Sugar‐Based Polyurethanes

“…The thermal stability of the novel PUs was investigated by thermogravimetric analysis and differential scanning calorimetry. This strategy provides a simple and versatile platform for the design of new materials whose functionality can be easily modifi ed to anchor diverse biologically active molecules.following: (a) the incorporation of functional groups in the diol moiety without previous protection, as hydroxyl, [ 8 ] carboxy, [9][10][11] alkynyl [ 5 , 12 , 13 ] or allyl groups, [ 14 , 15 ] and oxazolidine-functionalized PUs [ 16 ] or disulfi de bonds [ 17 ] among others; or (b) in certain cases, functional groups were previously protected as NHBoc moieties [ 18 ] or benzyl ether groups, [ 19 ] and later deprotected once the polymerization had taken place. The diisocyanates do not usually bear any functional group -apart from one example found in the literature (maleimide units).…”

“…[ 20 ] The methods mentioned above incorporate just one type of functional group each time, the preparation of different diol or diisocyanate monomers is required and poor control on the degree of functionalization is sometimes accomplished. In a previous paper of our group, [ 19 ] we had attempted the preparation of multihydroxylated PUs by using a conveniently protected sugar diol monomer in which secondary groups were blocked as benzyl ethers. Deprotection of secondary hydroxyl groups required severe reaction conditions and was poorly controlled.…”

Glutathione-Mediated Biodegradable Polyurethanes Derived from l-Arabinitol

“…[16][17][18][19][20] In our research group, we are interested in the preparation of new polyurethanes in order to make them biocompatible and more biodegradable. 21,22 In previous studies, we verified that the hydrolytic degradation of L-arabinitol and xylitol-based polyurethanes did not result in great reductions in their average molecular weight (M w ) unless drastic experimental conditions were used (reductions of 60% in M w were achieved at pH 10.0 and 80°C, after 39 days). 23 Searching for different approaches to enhance the degradability of polyurethanes in biological systems, we thought of disulfide bonds, as they are the bridging structure most commonly encountered in biological systems, and can be cleaved by the action of the natural tripeptide glutathione (γ-glutamylcysteinyl-glycine; GSH).…”

“…The homopolymers PU(ArBn-HMDI) and PU(ArMe-HMDI) were prepared from ArBn and ArMe, respectively, as described in earlier papers of our group. 22,23 The yields and physical properties of the homo-and copolymers are shown in Table 1. The polymerization solvent was THF when the L-arabinitol-based monomer was the main diol component in the polyurethanes.…”

Monomers and Macromonomers from Renewable Resources

“…A new family of linear polyurethanes and poly(ester -urethanes), prepared from both aliphatic and aromatic diisocyanates and isorbide [21] or conveniently protected sugar alditols, has recently been reported and the properties of the ensuing materials fully characterized [22] . This interesting investigation has been extended to include aliphatic biodegradable polyurethanes bearing L -arabinitol and 2,2 ' -dithiodiethanol [23] .…”