Synthesis and Hydrolysis Behavior of Side-Chain Functionalized Norbornenes

Abstract

[reaction: see text] The stabilities of various functionalized norbornenes that are monomers for the ring-opening metathesis polymerization (ROMP) in aqueous solution were evaluated toward hydrolysis under a range of temperatures (37, 60, and 80 degrees C) and pH values (3-9). All monomers contain hydrolyzable linkages to pendant functional groups, and conclusions were drawn relating to how the chemical diversity of these pendant functional groups, in accordance with the pH and temperature variations, affect hydrolysis of the aforementioned linkages. The hydrolysis was monitored by reverse phase HPLC analysis, and/or NMR spectroscopy. As expected, monomers containing ester linkages were fairly labile at higher pH values, while acetal-based linkers were cleaved at lower pH values. Beta-amino ester groups experienced a significant increase in hydrolysis rate, while carboxylic acid-containing monomers did not follow any clear trend. Saccharide-containing monomers exhibited unique behaviors for various pH values and temperature ranges.

The thermo responsive behavior of glycol functionalized ring opening metathesis polymers

“…Oligo(ethylene glycol) esters of norbornenes were anticipated to execute both requirements based on literature reports on ATRP of corresponding acrylate derivatives 40–44. However, research on ROMP as the polymerization method and using properly functionalized norbornenes is still in its infancy 45–47…”

“…Different kinds of monosubstituted norbornene derivatives (cf. Scheme ) were synthesized in a two step reaction 45. First, norbornene acyl chloride was prepared via [4 + 2] cycloaddition 50.…”

“…Modifying a procedure by Carlise et al,45 cyclopentadiene (1.25 mL, 15.1 mmol, 2 eq) was diluted with 15 mL dry CH 2 Cl 2 . Then, acryloyl chloride (0.62 mL, 7.56 mmol, 1 eq) was added dropwise.…”

“…[40][41][42][43][44] However, research on ROMP as the polymerization method and using properly functionalized norbornenes is still in its infancy. [45][46][47] Disubstituted norbornene derivatives (cf. Scheme 1) were synthesized via esterification of commercially available endo,exo-5-norbornene-2,3-dicarbonyl chloride (1 eq) with different types of ethylene glycol monoethyl ethers [tri(ethylene glycol)monoethyl ether, di(ethylene glycol)monoethyl ether, and an oligo(ethylene glycol)monomethyl ether with an average molecular weight of 350 g mol À1 , purchased from Sigma Aldrich, CAS Nr.…”

Novel degradable polymer networks containing acetal components

“…The copolymer network exhibited pH response because of the acetal molecular structure as one of its components [28]. Treated with a strong acid (HCl, 0.1 M/10 3 M) in THF for a certain time (see Table 1), the network disappeared and a clear solution formed.…”