Synthesis of Functional Sugar‐Based Polyurethanes

Abstract

Three new polyurethanes (PUs) with multiple pendant allyl groups were synthesized from L -arabinitol as versatile materials for the preparation of tailor-made PUs with varying degrees of functionalization. Their allyl functional groups can take part in thiol-ene reactions to obtain greatly diverse materials. Thus, six new highly functional PUs were prepared by click chemistry to give polymers with NHBoc [NH-CO-OC(CH 3 ) 3 ], amino, carboxylic, and 1,2-dihydroxyethyl side groups. 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. At most, debenzylation proceeded close to 70% after 5 d of reaction.Therefore, it would be of interest to fi nd a procedure to transform a certain polymer into functionalized new materials by means of a simple and straightforward reaction. To deal with this issue, we now present a strategy based on the use of di-and tri-O -allyl diol monomers for polymerization with aromatic or aliphatic diisocyanates

Synthesis of reduction sensitive comb‐like polyurethanes using click chemistry

“…As in the findings of previous works, and in addition to what has been mentioned above, the TG curve of any DiT‐derivative copolymer also displayed a sharp first degradation step at temperatures ranging from 220 °C to 280 °C which is due to the thermal cleavage of disulfide bonds (Fig. ).…”

“…Thus, click chemistry (CC) has emerged as a widespread approach that uses only the most practical and reliable chemical transformations . To exemplify this methodology, some functional PU have been successfully prepared and their polymer structures further modified by a thiol‐ene coupling reaction with the corresponding incorporation of functional groups such as amine, carboxylate, hydroxyl, and dihydroxyl moeties – …”

A new biodegradable polythiourethane as controlled release matrix polymer

“…The rational design of polymers tailored to exert biomedical properties plays a significant role in the development of controlled drug delivery systems (Ferris et al, 2012). Thus, although polyurethanes are widely investigated due to their low toxicity, potential biodegradability, biocompatibility, and versatile structures (Weisenberg and Mooradian, 2002), their sulfur analogs, polythiourethanes (PTU), containing -NH-CO-S-linkages are a relatively poorly investigated group of polymeric materials (Kultys et al, 2008).…”

Conformationally restricted linear polyurethanes from acetalized sugar‐based monomers

“…So, although syntheses of polyurethanes have recently been carried out by us8 using sugar‐derived monomers with free hydroxyl groups and alkyl or aryl isocyanates at low temperature, a certain degree of cross‐linking was observed in the obtained polymers, as revealed by elemental analyses and the 1 H NMR and 13 C NMR spectra. In our research group we have used various O ‐protected sugar‐based monomers for the preparation of a series of linear [ m,n ]‐type polyurethanes by polycondensation with 1,6‐hexamethylene diisocyanate ( HMDI ) or 4,4′‐methylene‐bis(phenyl isocyanate) ( MDI ) 9–13. Among the diverse sugar‐derived monomers that have been explored, 1,4:3,6‐dianhydrohexitols have been given particular attention for the synthesis of linear polymers 14.…”