An Acyllactam-Type Growable End Group Formed in the Anionic Polymerization of a Bicyclic Oxalactam. The Isolation of the Polyamide and Its Use as an Activator in the Polymerization of 2-Pyrrolidone

Abstract

ABSTRACT:A bicyclic oxalactam, 8-oxa-6-azabicyclo[3.2. l)octan-7-one was anionically polymerized in dimethyl sulfoxide at room temperature and the resulting hydrophilic polyamide having an acyllactam-type growable chain end was isolated from the polymerization system. The reactive end group was found to be easily converted to other functional groups by the hydrolysis or aminolysis with suppressing the simultaneous decomposition of the polyamide chain. The terminal acyllactam group in the polyamide, which was used as an activator in the anionic polymerization of 2-pyrrolidone, was quantitatively consumed and all of the macromolecular activator could be incorporated into the resulting copolymer. The thermal behavior and crystallization of the AB-type block copolymer composed of the hydrophilic polyamide and nylon-4 segments were influenced by the characteristics of the hydrophilic polyamide segment. KEY WORDSBicyclic Oxalactam / Anionic Polymerization / Reactive End Group / 2-Pyrrolidone / Block Copolymer / The polymerizability of a bicyclic oxalactam, 8-oxa-6-azabicyclo[3.2. l ]octan-7-one (abbreviated as BOL, 1), is so high that it can be easily polymerized using anionic catalysts under mild conditions such as in dimethyl sulfoxide (Me 2 SO) at room temperature,1-3 which should be desirable for suppressing possible side reactions. In fact, the resulting hydrophilic high molecular weight polymer (polyBOL, 2) has a purely alternating arrangement of an amide group and a tetrahydropyran ring along the main chain but has no other repeating unit ( eq 1 ). 1 -3 The vinylbenzyl-type polyamide macromer (3) was prepared by the anionic polymerization of BOL followed by the reaction with p-vinylbenzylamine. 4 • 5 This suggests that the generated acyllactam-type growable chain end is not destroyed by any side reaction during 321

Synthesis of novel block copolymers containing polyamide4 segments and control of their biodegradability

“…In our previous work,16 the moisture adsorption of similar AB‐type block copolyamides ( 7 ) was examined and the amount of water adsorbed on the block copolyamides was unexpectedly lower than not only that on homopolyamide4 ( 1 ) but also that on polyBOL at high relative humidity. In addition, both films of homopolyamide‐4 and the AB‐type block copolyamides ( 7 ) obtained by casting from their 2,2,2‐trifluoroethanol solution were examined to be amorphous, and the crystallinity of the latter was proved to increase during the adsorption of water from the X‐ray diffraction and thermal analyses 16. Since the glass transition point of polyamides is known to decrease below room temperature with the adsorption of water, the high hygroscopicity of the polyBOL domain is inferred to decrease its glass transition point.…”

“…The anionic polymerization of the bicyclic lactam ( 4 ) proceeds under mild conditions in a homogeneous phase, which is desirable for suppressing possible side reactions, to give the polyamide with an acyllactam‐type growable chain end ( 12 ) 16, 17. In this work, the polyamide with acyllactam groups at both chain ends ( 13 ) was also prepared in the anionic polymerization of 4 with the use of N,N ′‐isophthaloylbis‐(8‐oxa‐6‐azebicyclo[3.2.1]octan‐7‐one as an activator.…”

“…The polyamide‐type activators ( 12 and 13 ) were soluble in 2‐pyrrolidone ( 2 ) and conveniently provided for its anionic polymerization using potassium t ‐butoxide as a catalyst. The polymerization proceeded in a similar way with the potassium pyrrolidonate‐catalyzed polymerization described in our previous article 16…”

“…After the evaporation of the solvent, the crude product was recrystallized from a n ‐hexane‐benzene mixed solvent: yield, 2.6 g(17%); mp, 173°C. N ‐Benzoyl‐2‐pyrrolidone,24, 25 N ‐benzoyl‐8‐oxa‐6‐azabicyclo[3.2.1]octan‐7‐one,24 and N,N ′‐terephthaloylbis(ε‐caprolactam)16, 26 were prepared from the corresponding lactams and acid chlorides by a similar method. Tolylene‐2,4‐diisocyanate was distilled in vacuo , after being kept in a sealed flask for a week.…”

“…Polyoxyethylene glycol ( 3 ) with narrow molecular weight distribution is commercially available and known to be soluble in water and to be biodegradable 14, 15. A bicyclic lactam, 8‐oxa‐6‐azabicyclo[3.2.1] octan‐7‐one ( 4 ), can be polymerized anionically to give a hydrophilic polyamide (polyBOL, 5 ) under mild conditions, such as at room temperature in dimethyl sulfoxide 16, 17. PolyBOL ( 5 ) degraded in phosphate buffer solution (pH 7.5), although the degradation rate was not as high 10…”