Chemical transformation of nitrile to reactive oxazoline functionality on a preformed polymer

Abstract

SYNOPSISThe chemical transformation of nitrile to oxazoline functionality via a soluble zinc saltcatalyzed reaction was conducted on a series of nitrile-containing copolymers, i.e., styreneacrylonitrile (SAN) and nitrile rubbers. The results show that triad tacticity of the acrylonitrile groups is important in understanding the relative reactivity of SAN copolymers. Furthermore, the dielectric properties of the comonomer is also a prime factor in understanding the different degrees of reactivity of SAN, nitrile rubbers, and its hydrogenated analog forms. Enhanced reaction rates are noted with higher dielectric constants. I NTRO DUCT10 NIt is well known that a majority of polymer blends require a compatibilizer in order to achieve a synergism in properties.'-' These compatibilizers are polymeric in nature, spanning the interfacial region between otherwise strongly phase-separated polymers. These compatibilizers are typically formed during melt processing, i.e., the blending step." This mode of formation is a solventless process and economic, and, in addition, the compatibility is formed in situ between the two phases. As a result of its location, the compatibility is immediately available to lower surface tension, promote interfacial adhesion, and lower the domain size of the dispersed phase. Markedly improved stress-strain properties result. Although this mode of blend formation is highly desirable, the procedure is limited to the number of commercially available polymers capable of being utilized under reactive processing conditions.Recently, a synthetic procedure was developed to incorporate low levels of oxazoline functionality onto styrene-acrylonitrile ( SAN) copolymers. It was noted that oxazoline groups are reactive toward a * To whom correspondence should be addressed. relatively wide range of functional groups. As a result, the utility of SAN copolymers as a blend compatibilizer should be substantially broader. In this report, we detail the oxazoline functionalization of a broad range of laboratory-synthesized and commercially available ( i.e., preformed) polymers containing nitrile groups. These families of materials include thermoplastics ( SAN copolymers) and rubbers ( nitrile rubbers, hydrogenated nitrile rubbers, and liquid rubbers). The former copolymers include styrene-nitrile copolymers which include random copolymers of SAN, alternating copolymers of SAN (alt-SAN) , and random copolymers of styrene-methacrylonitrile ( SMAN ) , while the latter systems include random copolymers of butadieneacrylonitrile ( NBR) and their hydrogenated analogs (HBNR). Therban 1701 possessed 34 wt % acrylonitrile and 100% of double bonds hydrogenated, and Therban 1701 SHRD possessed 34 wt % acrylonitrile and 96% of double bonds hydrogenated and were obtained from Mobay Chemicals. The reagents and solvents employed in this study were used as received (Aldrich Chemical). Zinc chloride was dried in a vacuum oven at 110°C for 2 days. 'H-NMR spectra were obtained from a 300 MHz Varian XL-300 instrument. EXPERIMENTAL

Reactive Compatibilization of NBR/EPDM Blends by the Combination of Mercapto and Oxazoline Groups

“…[26] In a typical procedure, 100 g NBR copolymer were dissolved in 500 ml 1,2-dichlorobenzene at 140 8C. Then, 48 g of 2-aminoethanol were introduced to the reaction vessel.…”

“…The resulting crosslinked polymer chains are expected to be formed at the interface, generating compatibility in these blends. The choice of NBR-ox as the co-reactive partner for mercapto-modified polymers is based on the feasibility of modification of nitrile groups of NBR and other copolymers containing acrylonitrile components (SAN resin or ABS) into oxazoline groups by using ethanolamine in the presence of appropriate catalyst, [26][27][28] and on its reactivity towards several other reactive groups, such as carboxylic acid, amine, anhydride, epoxy and mercapto groups. [29,30] Because of its reactivity, oxazoline-functionalized polymers have been considered excellent and effective compatibilizing agents for several polymer blends.…”

Polymeranaloge Umsetzung von Poly(butadien‐co‐acrylnitril) mit 2‐Aminoalkoholen in Lösung und in der Schmelze

“…Als Aminoalkohol wurde fast ausschlieûlich 2-Aminoethanol eingesetzt [10, 24 ± 28]. Hinsichtlich der eingesetzten Polymere und Aminoalkohole bestehen groûe Unterschiede in der Reaktivität [24,26,29,30]. H S E I H et al konnten in kinetischen Untersuchungen zeigen, dass die Reaktivität nitrilhaltiger Copolymere in folgender Reihe zunimmt: HNBR < NBR < SAN [24].…”

Einfluss der Reaktionsparameter bei polymeranalogen Umsetzungen in der Schmelze am Beispiel der Umsetzung von Poly(styrol‐co‐acrylnitril) mit Aminoalkoholen

“…Für die polymeranalogen Umsetzungen besteht dabei die Möglichkeit, entweder in Lösung [7,8] oder in der Schmelze [10 ± 13] zu arbeiten.…”