Mechanical properties and transition temperatures of copolymers of N‐n‐alkylacrylamides and vinylidene chloride

Abstract

synopsisMechanical and solution properties, melting transitions, torsional stiffness temperatures, Tf, and selected modulus-temperature curves are presented for copolymers of the N-n-alkylacrylamides with vinylidene chloride. Copolymers were prepared at 6OoC across the range of compositions, using &s comonomers N-n-butyl-, octyl-, dodecyl-and oleyl-acrylamide, which have amorphous side-chains, and N-n-octadecyl acrylamide and n-octadecyl acrylate whose side-chains are crystalline. The mechanical properties reflected the effect of the decline in backbone crystallinity and the simultaneous development of strong intermolecular interactions in the amorphous stage. Copolymers were stiff or showed brittle failure across the compositional range except when intermolecular forces were reduced (with n-octadecyl acrylate) and side-chain crystallization eliminated (with N-oleylacrylamide). These systems and the n-dodecylacrylamide copolymers had yield strengths less than brittle strengths and substantial elongations.Backbone crystallinity w&s eliminated a t about 15 mole % amide and side-chain crystallinity vanished at less than 10 mole yo of the amide in the N-n-octadecylacrylamide series. No depression in side-chain melting point occurred with dilution by segments of vinylidene chloride. Over-all decline in the flex-temperature was the normal monotonic function of composition except that values increased in magnitude at high vinylidene chloride contents, the effect presumably being caused by the presence of crystallinity.An empirical equation was developed which permitted the calculation of Tf for any N-n-alkylacrylamide composition with any number of carbon atoms in the side-chain, above 3.

Mesophase structures of solid poly( N ‐alkylacrylamides) as revealed by SAXS

“…3 by plotting the experimental i and j values (estimated error bars are included) in the generalized interface-curvature diagram, as delineated in ref. 9) It is seen that the highly ordered PAA 12 and PAA 14 as well as the weakly ordered PAA 16 and PAA 18 are located in the phase diagram in a very systematic fashion, where both normalized interface area i and curvature j increase with increasing alkyl tail length. The allocation of all data points is far off the limiting value of plane lamellae, i. e., i = 2 and j = 0, but in the region of lamellar systems populated by major undulations of the interface.…”

“…The experimental scattering diagram of PAA 12 (synchroton radiation with point focus), its description with the resolution smeared peak sequence of the ideal structure, as well as the computer model of the connected ideal 3D structure are shown in Fig. 4.…”

“…The knowledge of the i and j values was used to test the different structure models for the quantitative description of the scattering curves of the highly ordered samples PAA 12 and PAA 14 . For that, we simulated the different phase structures with all possible types of undulations and recalculated the scattering diagram; structure variation was performed under the restriction of holding i and j close to the experimental values which remarkably reduces the variety of possible structures and the accessible parameter space.…”

“…The resulting poly(N-alkylacrylamides) are highly viscoelastic, rubberlike materials. The equilibrated film from PAA 12 to PAA 18 shows under quiescent conditions a hazy white texture under the polarization microscope. Any kind of mechanical deformation of these poly(N-alkylacrylamides), however, produces an extremely high birefringence characterized by coloured domains extending in the cm-region.…”

Synthesis and Side-Chain Crystallization of New Comb-Like Polymers from 2-Amino-4-(N-alkylanilino)-6-isopropenyl-1,3,5-triazines

“…Subsequently, many studies on the Tg, the crystallization of side-chains, and the mechanical properties were reported for poly(p-nalkylstyrenes ), 5 poly(n-alkyl vinyl ethers), 6 poly(N-n-alkylmaleimides), 7 poly(n-alkyl itaconates), 8 and poly(N-n-alkylacrylamides). 9 Yokota et al1°-13 investigated the synthsis, structure, and thermal properties of widelyspaced comb-like polymers. In addition, polymerized Langmuir-Blodgett (LB) film was obtained by the polymerization of N-octadecylacrylamide in LB multilayers.…”