Comonomers hydrolytically resistant

Our group has examined copolymers and terpolymers from the hydrolytically resistant comonomers 1 Ij and 2 in which the cation and anion are evenly spaced from the macromolecular Imckbone (Scheme 2) 26-30). At equimolar incorporation of the monomers into the copolymer, a minimum in the apparent viscosity in water and a maximum in apparent viscosity in 0.514 MNaCl was observed - consistent with the so-called antipolyelectrolyte effect Simile effects are observed when acrylamide (3) is incorporated as a termonomer. A three-fold enhancement in viscosity was observed at a molar ratio of 11 13 76 for monomers (la 2 2) in 0.5 MNaCl as compared to deionized water (29). 

Litt reported that bulky comonomers and sequenced copolymers impart improved water resistance without sacrificing conductivity. However, one sample shown in Figure 22 became brittle after 3 weeks in water above 90 °C. Litt also observed better hydrolytic stability when the unsulfonated diamine with flexible ether linkages was incorporated. 

Vinyl substituted cyclic hemlamidals 2 and their Interconvertible acetal precursors (eg. acrylamldo-butyraldehyde dimethyl acetal 1) were Incorporated as latent crosslinkers and substrate reactive functional comonomers In solution and emulsion copolymers. Some use and applications data for copolymers prepared with these new monomers are presented. They show low energy cure potential, long shelf life and high catalyzed pot stability In solvent and aqueous media, good substrate reactivity and adhesion, and good product water and solvent resistance. They lack volatile or extractable aldehyde (eg. formaldehyde) components and show enhanced reactivity and hydrolytic stability with amines and diol functional substrates. 

The resistance to hydrolysis of a polycyanoacrylate can also be improved by copolymerization with another monomer. In fact, the cyanopentadienoates cited above should also be considered comonomers. An electron-rich vinyl monomer like styrene and a cyanoacrylate ester will spontaneously copolymerize a short time after mixing. The product is a one-to-one alternating copolymer. This reaction has been used to make a two-part adhesive with better hydrolytic stability than the standard cyanoacrylate. " The carbon dioxide evolved from a suspension of the polymer in boiling water was measured to follow the degradation. After eight hours, polymethyl cyanoacrylate had lost 28% carbon dioxide by hydrolysis and decarboxylation of the polycyanoacrylate ester groups, while the copolymer had lost none. However, this improvement in moisture durability is achieved at the expense of the convenience of a one-part adhesive. 

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