Polyamide Segments Research Articles

Synthesis and Characterization of Segmented Copolymers of a Methylated Polyamide and a Thermotropic Liquid Crystalline Polyester

ABSTRACTA block copolymer consisting of liquid crystalline polyester segments and methylated polyamide segments has been synthesized. Solution polycondensation of acid chloride end-capped poly(terephthaloyl phenylhydroquinone) (LCP portion) with an amine terminated poly(N,N'-dimethylethylene sebacamide) was utilized to prepare the block copolymer. Characterization by differential scanning calorimetry, infrared spectroscopy, thermogravimetric analysis, optical microscopy and elemental analysis has been performed to verify the existence of the block copolymer that may have potential as a molecular composite material or self-reinforcing thermoplastic.

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

A bicyclic oxalactam, 8-oxa-6-azabicyclo[3.2.1]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.

Synthesis and preliminary characterization of rubber-polyamide multiblock copolymers

“Hard-soft” multiblock copolymers,(AB)n type,have been prepared by incorporating rubbery segments into a polyamide 6,10 chain according to a two steps procedure. As soft segments,telechelic polybutadiene or poly(butadiene-co-acrylonitrile) oligomers have been used.The prepared copolymers have been characterized by IR spectroscopy and differential scanning calorimetry. Two different and well defined glass transitions have been observed indicating a phase segregation for the rubbery and polyamide segments.

Effect of microstructure of poly(propylene-oxide)-segmented polyamides on platelet adhesion.

The relationship between microstructure and platelet adhesivity of six types of poly(propylene oxide) (PPO)-segmented polyamides based on the polyamide segments nylon 210, 310, 410, 510, 610, and 710 were investigated. These multiblock PPO-segmented copolymers were prepared by interfacial polycondensation. Physical characterization of these copolymers was by means of thermal analysis, transmission electron microscope, wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS). The WAXD and SAXS measurements showed that the copolymers had microstructures containing crystalline and amorphous phases and that these microstructures, represented by means of crystallite thickness and long period, varied with incorporation of PPO segments. Blood compatibility of these copolymers was evaluated by estimating the amount of adhering platelets on the copolymer surfaces. The amount of adhering platelets was minimum for the surfaces of the copolymers having a crystallite thickness of 6.0-6.5 nm and a long period of 12-13 nm. This result suggests that the particular size and distribution of the crystalline and amorphous phases in the copolymer could be determining factors for suppressing platelet adhesion on the copolymer surface, and that the control of these factors could lead to ideal antithrombogenic polymers.

Vinylbenzyl-Type Polyamide Macromer Synthesized from Bicyclic Oxalactam. Preparation and Characterization of Graft Copolymer Composed of Polystyrene as a Stock and Hydrophilic Polyamide as Branches

Vinylbenzyl-type polyamide macromers (1) of various average molecular weights (Mn; 3900, 5400, and 8400) were prepared by the anionic ring-opening polymerization of a bicyclic oxalactam, 8-oxa-6-azabicyclo[3.2.1]octan-7-one (abbreviated as BOL, 2) followed by a reaction with p-vinylbenzylamine. The relative reactivity of the macromer (M1) in the radical copolymerization with styrene (M2) was found to be lower than that of p-methylstyrene from the estimation of the reciprocal monomer reactivity ratio (1/r2). The resulting graft copolymer composed of a polystyrene stock and polyamide branches was characterized by structural analysis, solubility test, and determination of moisture sorption. Two kinds of transparent binary blend films, which were i) the graft copolymer and homopolystyrene and ii) the graft copolymer and polyBOL, were cast on a glass plate from the corresponding chloroform and chloroform-methanol (9:1) solutions, respectively. In the case of the former film comprising mainly polystyrene, the hydrophilic polyamide segment of the graft copolymer as a really minor component was found to be located on the glass-side surface from the contact angle measurement and the attenuated total reflection-infrared spectroscopy.

Polyether‐segmented polyamides as a new designed antithrombogenic material: Microstructure of poly(propylene oxide)‐segmented nylon 610

AbstractA series of segmented polymers based on poly(propylene oxide) (PPO) and nylon 610 was characterized. Transmission electron microscopic observations revealed spherulitic structures similar to those of semicrystalline homopolymers. Dynamic mechanical measurement and thermal analysis suggested distinct phase separation between the PPO and polyamide segments, which is generally observed for amorphous block copolymers systems. Moreover, density and X‐ray diffraction measurements indicated that the crystallization of the polyamide segments is promoted by the introduction of PPO segments in the copolymer. This is probably correlated with unique growth of crystalline lamellae in the PPO‐segmented polyamides.

Characterization of the Microstructure of Poly(propylene oxide)–Segmented Polyamide and Its Suppression of Platelet Adhesion

The relationship between microphase-separated structures and antithrombogenicities of poly(propylene oxide) (PPO)–segmented polyamides of various polyamide segment lengths was studied. Transmission electron microscopic observation revealed fibrillar lamella structures to be present on the copolymer surfaces. Dynamic mechanical and thermal scanning measurements showed the existence of two mechanical relaxations attributable to micro-Brownian motions of the PPO and polyamide segments, indicating that the PPO and polyamide segments formed distinctly separated microdomain structures. Moreover, wide-angle X-ray diffraction and small-angle X-ray scattering measurements indicated these copolymers to be different in their microstructures with respect to size and distribution of crystalline and amorphous domains even though the crystalline structure was essentially the same as that of nylon 610. The degree of platelet adhesion and aggregation was significantly minimized on the surface of the copolymer, in which the average diameter of the crystalline and amorphous domains were 6.42 nm and 5.18 nm, respectively. This suggests that the size of segmented polyamide microdomains may be a determining factor in antithrombogenicity.