Synthesis and Solution Properties of Norbornene Based Polybetaines

Abstract

Ring-opening metathesis polymerization (ROMP) was used to synthesize novel norbornene based polycarboxy- (d-Poly 3a and d-Poly 3b) and polysulfobetaines (Poly 3c) using the third generation Grubbs’ catalyst (G3) as the initiator. Hydrophobicity of the polycarboxybetaines was varied by changing the bridging group of the norbornene backbone. A protective group approach was utilized to prevent any possible retardation in the polymerization due to interactions of the carboxylate functionality with the catalyst and to provide ease of characterization. The tert-butyl ester protected precursor polymers (Poly 3a and Poly 3b) were deprotected under acidic conditions to yield the corresponding polycarboxybetaines with very narrow polydispersity indices, ranging from 1.03 to 1.15. This method allowed excellent control over the molecular weight distributions compared to the direct polymerization approach. When molecular weight was plotted against the theoretical degree of polymerization (DP), linear relationships were obtained for both 1H NMR and GPC-MALLS data. Oxanorbornene based polycarboxybetaine (d-Poly 3a) was studied in aqueous 0.1 M NaBr solution by dynamic light scattering (DLS) and no significant aggregation was observed. An attempt was made to determine the acid ionization constant (K a) of the carboxylate group, which led to the discovery that the cyclic imide of these particular monomers is easily ring opened under basic conditions.

Hydrophilic Modifications of an Amphiphilic Polynorbornene and the Effects on its Hemolytic and Antibacterial Activity

“…The same reaction conditions were employed to obtain 2 , which was further alkylated with 4-bromobutanoic acid tert -butyl ester to yield the positively charged M2 as the quaternary ammonium salt, leading to the zwitterionic functionality upon deprotection (Scheme 1). 40 M3 was synthesized according to a previously published procedure. 34 All monomers were characterized using NMR techniques.…”

Structures and Synthesis of Zwitterionic Polymers

“…This concerns in particular ring opening metathesis polymerization (ROMP), whereas metathesis (cyclo)polymerization of zwitterionic alkynes was reported already some time ago [348]. The new zwitterionic polymers reported have all been based on cycloolefins, mainly on strained tricyclic imides derived from exo-7-oxa-norbornenedicarboxylic acid ( Figure 6) [349][350][351][352][353][354][355][356]. This has enabled the facile preparation of polyzwitterions with double bonds in their backbone.…”

“…Figure 6. Zwitterionic monomers employed in ring opening metathesis polymerization (ROMP), including phosphobetaine 34 [352], sulfobetaines 35 and 36 [349,350,354,357], and carboxybetaines 37 and 38 [350,357]. Still, different from the phosphobetaine and sulfobetaine monomers, the carboxylate group is nucleophilic enough in the less acidic carboxybetaines (x > 1 in VII, Figure 1) to compete with other ligands for complexing the metal center of the ROMP catalysts.…”

“…As the cleavage of such an ester function often has the character of the deprotection step in protecting group chemistry, especially if tert-butyl esters are employed [93,94,349,357,[398][399][400][401][402], it generally provides excellent yields. Thus, chances are very high to obtain rather clean polyzwitterions if not the amine, but the quaternized ammonium derivative is already engaged as monomer in the polymerization.…”

Epoxide tethering of polymeric N-halamine moieties

“…The increasing number of healthcareassociated infections requires the prevention of biofilm formation on surfaces to reduce the risk of spreading pathogenic microorganisms (Gagliotti et al 2011). Therefore, quaternary ammonium salts (Colak and Tew 2008;Klibanov 2007;Sauvet et al 2000), metal ions (El-Shishtawy et al 2011), N-halamines (Kenawy et al 2007;Sun and Sun 2002;Goddard and Hotchkiss 2008;Worley et al 2003;Zhao et al 2011), and a variety of materials have been used as biocidal coatings.…”