On the synthesis of poly(ε-caprolactam)—poly(butadiene-co-acrylonitrile) block copolymers for the reaction injection molding process

The liquid rubbers Hycar ATBN and HTBN were used in the preparation of poly(ε-caprolactam)—poly(butadiene-co-acrylonitrile) block copolymers intended for reaction injection molding by the anionic polymerization of ε-caprolactam. The conversion of Hycar end groups to polymerization growth centers and the conditions of polymerization influence the crystallization, morphology, and mechanical properties of the product through its molecular structure. The contribution of individual reactions to this molecular structure is discussed.     

Adhesive properties of systems of partially neutralized carboxyl-terminated liquid rubber–anhydride–bisepoxide

Systems of partially neutralized carboxyl-terminated liquid rubber (PNCTLR)-anhydride–bisepoxide were evaluated for adhesive properties. The PNCTLRs were prepared by the partial neutralization with MgO and CaO from a polymer of butadiene (BD) (Hycar CTB 2000X162) and copolymers of BD–acrylonitrile (Hycar CTBN 1300X8 and CTBNX 1300X9). As the bisepoxide, bisphenol A diglycidyl ether was used, and hexahydrophthalic anhydride was the anhydride used. The adhesive properties of the metal-containing systems were superior to those of the reference systems not containing metal, owing to the polarity effect of the metal carboxylate groups. Further, the CTBN- and CTBNX-series systems showed higher tensile shear and peel strengths than the CTB-series systems, owing to the enhanced polarity effect of the nitrile groups.     

Copolymers of ε-caprolactam and polypropylene oxide via anionic polymerization: synthesis and properties

Copolymers with an elastic polypropylene oxide (PPO), middle block in the main chain of poly(ε-caprolactam) were synthesized via activated anionic ring opening polymerization of ε-caprolactam (CL) in the presence of a basic initiator sodium salt of CL (Na-CL) and effective bifunctional polymeric activators (PACs). By varyng the molecular weight, two types of PACs were synthesized based on carbamoyl derivatives of hydroxyl terminated PPO with isophorone diisocyanate and were blocked with CL. The formation of copolymers has been confirmed by proton nuclear magnetic resonance spectroscopy (¹H–NMR) and Fourier transform infrared spectroscopy (FT-IR). The influence of the molecular weight of the PACs, the CL/PAC ratio and polymerization conditions on the conversion, intrinsic viscosity and polymerization kinetics, was investigated. The calorimetric, wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), notched impact test and dynamic mechanical thermal analysis (DMTA) were performed to estimate the influence of the composition ratio and the type of PACs on the physical, thermal, and mechanical properties of the copolymers. The use of the synthesized PACs reduced the polymerization time to several minutes. The copolymers showed improved impact resistance up to more than two times higher than those of the polyamide 6 (PA-6) homopolymer, without significant changes in their high melting temperatures.     

Toughening and phase separation behavior of nylon 6–PEG block copolymers and in situ nylon 6–PEG blend via in situ anionic polymerization

We have prepared in situ molded products of morphologically different nylon 6/polyethylene glycol (PEG) copolymers and their blends via anionic polymerization of ε-caprolactam in the presence of several kinds of PEG derivatives using sodium caprolactamate as a catalyst and carbamoyl caprolactam derivative as an initiator. Three carbamoyl caprolactams, such as tolylene dicarbamoyl dicaprolactam (TDC), hexamethylene dicarbamoyl dicaprolactam (HDC), and cyclohexyl carbamoyl caprolactam (CCC), with different functionalities and activities were used. Phase separation behavior was investigated by dynamic mechanical thermal analysis (DMTA) and DSC during in situ polymerization and melt crystallization. The mechanical properties of these molded products were evaluated. PEG segments in the block copolymers showed amorphous characteristics, whereas a large fraction of unreacted PEG segments was crystallized in as-polymerized samples, except for the products obtained using the CCC activator. The presence of PEG derivatives retarded the crystallization of nylon 6 part during in situ polymerization as well as melt crystallization. However, PEG segments did not alter the crystalline structure of nylon 6, showing α-crystalline modification. The nylon 6–PEG–nylon 6 triblock copolymers showed the highest impact strength, whereas the nylon 6–PEG diblock copolymers and in situ nylon 6–PEG blends showed no improved toughness. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1285–1303, 1999     

Block polymers from isocyanate-terminated intermediates. IV. Properties of cured butadiene–ε-caprolactam block polymers

Butadiene–ε-caprolactam block polymers containing a high proporation of 1,2 units in the butadiene-segments were synthesized and physical properties were measured on the cured copolymers. Flexural strength and impact resistance both increase regularly with increasing ε-caprolactam content in peroxide cured copolymers. This behavior is explained by the higher values of flexural modulus and impact resistance for poly(ε-caprolactam) compared with peroxide-cured polybutadiene resins. Copolymers reinforced with silica showed higher heat distortion temperatures but lower impact resistance than corresponding unfilled samples. Arrhenius plots of flexural properties at various test temperatures were linear. Both flexural modulus and strength decreased regularly with increasing test temperature. Flexural properties of filled copolymers were relatively unaffected by heat aging up to 204°C for several weeks, however, dramatic decreases in these properties were noted in a matter of days when heat aging was done at 260–316°C. These results are explained by the rapid degradation of poly(ε-caprolactam) above its melting point. Block polymers whose butadiene segments contained a high proportion of 1,4 units were also synthesized. These copolymers were elastomeric when cured with either sulfur or peroxide.     

Ionic crosslinking of carboxyl-terminated liquid rubbers with metal oxides

Ionic crosslinking of carboxyl-terminated liquid rubbers with metal oxides and metal carbonates, mainly with the former, were investigated. The liquid rubbers used were a polymer of butadiene (Hycar CTB 2000X162) and a copolymer of butadiene–acrylonitrile (Hycar CTBN 1300X8). The CTBN ionically crosslinked rubbers obtained showed higher tensile strength than the CTB series, due to the polarity effect of the nitrile groups. The ionic rubbers cured with MgO and CaO were studied in detail, and it was found that their tensile strength increased markedly with increase in the metal oxides used, and in addition white carbon and carbon black showed remarkable reinforcing effects. The properties such as tensile strength, elongation, Shore A hardness, and melt index are influenced by humidity. It is characteristic of these ionically crosslinked rubbers that they can be successfully reprocessed.     

Polyamide‐6‐b‐polybutadiene block copolymers: Synthesis and properties

Polyamide‐6 (PA6)/polybutadiene (PB) block copolymers were synthesized with macroactivators (MAs) based on hydroxyl‐terminated polybutadiene functionalized with diisocyanates and having three N‐acyllactam chain‐growing centers per molecule. Two different diisocyanates, hexamethylene diisocyanate and isophorone diisocyanate, were applied as precursors for the MAs. The sodium salt of ε‐caprolactam was chosen as an initiator. The influence of the MA type and concentration on the anionic ring‐opening polymerization of ε‐caprolactam at 180°C was studied. A large percentage of the gel fraction in the copolymers was estimated, indicating crosslinked macromolecules. The structure and phase behavior of the copolymers were investigated with differential scanning calorimetry, wide‐angle X‐ray scattering, thermogravimetric analysis, and dynamic mechanical thermal analysis. In the copolymers, only the PA6 chains crystallized, and the crystallinity depended on the PB content. Different glass‐transition temperatures for the PB blocks and PA6 blocks were observed, indicating microphase separation in the copolymers. The mechanical properties of the copolymers were studied by notched impact testing and hardness measurements. The impact strength increased linearly with the soft component concentration up to 10 wt % and reached values six times higher than those of the PA6 homopolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 711–717, 2003     

Structure and thermal behavior of nylon‐6/polytetrahydrofuran triblock copolymers obtained via anionic polymerization

The structure, crystallization, and phase behavior of nylon6‐b‐polytetrahydrofuran‐b‐nylon6 triblock copolymers synthesized via activated anionic polymerization have been studied. The composition, molecular weight of polytetrahydrofuran (PTHF) soft block, and type of polymeric activators (PACs) have been varied. Differential Scanning Calorimetry (DSC), Wide‐Angle X‐ray Diffraction (WAXD), Transmission Electron Microscopy (TEM), and Polarized Light Microscopy (PLM) experiments have revealed that in triblock copolymers only the nylon‐6 component crystallizes while PTHF segments are amorphous. The soft blocks do not alter the spherulitic crystalline structure of nylon‐6 and hard blocks crystallize in the α‐modification. The degree of crystallinity decreases with increasing PTHF concentration. The phase behavior has been investigated by Dynamic Mechanical Thermal Analysis (DMTA). Two different glass transition temperatures (T_g) for all samples have been observed. This indicates that nylon‐6 and PTHF segments are not molecularly miscible and the copolymers are microphase separated. The mechanical properties of the copolymers synthesized have been evaluated. Nylon‐6 copolymers with soft block concentrations up to 10 w/w %, exhibit improved notched impact strength in comparison to the nylon‐6 homopolymer, retaining relatively high hardness and tensile strength. All copolymers possess low water absorption and good thermal stability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1448–1456, 2002; DOI 10.1002/app.10448     

Polymerization of Lactams: 57. G.l.c. and n.m.r. analysis of the anionic copolymers of 2-pyrrolidone with 6-caprolactam and 8-octanelactam

The activated anionic copolymerization of 2-pyrrolidone (PD) with 6-caprolactam (CL) or 8-octanelactam (OL) proceeds even above the ceiling temperature for PD homopolymerization. At high temperatures, the copolymerizations are accompanied by the depolymerization of PD sequences, which is more pronounced with the copolymers with CL. The copolymers obtained probably exhibit a constitutional heterogeneity and contain considerable amounts of low-molecular weight fractions. This may be the reason why the content of comonomers in the prepared copolymers determined by g.l.c. did not agree with that found by ¹H n.m.r. or ¹³C n.m.r. spectroscopy. The copolymers with CL had in part a block structure and also an alternating character, depending on temperature and polymerization time, while random copolymers were obtained at high temperatures. The copolymers with OL tended mostly to alternation.     

Polymerization of lactams, 87. Block copolymers of poly(ϵ-caprolactam) and polybutadiene prepared by anionic polymerization. Part I: Preparation and properties

The effect of the polymerization conditions on the properties of poly(?-caprolactam)-polybutadiene block copolymers prepared by polymerization casting through anionic polymerization of ?-caprolactam initiated with potassium salt of ?-caprolactam in the presence of α,ω-dihydroxy-polybutadiene and isocyanates or their blocked derivatives as functionalizing agents was investigated. The influence of the content of telechelic polybutadiene, its molecular weight, type of diisocyanate, and polymerization temperature on the fundamental mechanical properties of the prepared materials and on the polymerization rate was evaluated.     

Synthesis by reactive processing of block copolymers of Nylon 6 / Poly (ether-esteramide)

Summary Block copolymers of nylon 6 with 10, 15 and 20% of poly (ether-esteramide) as elastomeric phase were synthesized by reactive processing. These materials are obtained by the anionic polymerization of -caprolactam in the presence of a linear prepolymer of poly (ether-esteramide) with a Grignard reagent. Differential Scanning Calorimetry (DSC), torque rheometry and formic acid test were used to characterize the obtained copolymers. The results showed that block copolymers of Nylon 6 were formed. The melting temperature and the crystallinity of the copolymer decreased when the elastomer phase content increased. Two Tgs appeared; the blocks of the copolymers were not miscible. We calculate the size of nylon 6 blocks for each composition. The physical-mechanical behavior was also studied. More flexible materials were obtained when the soft phase content in the copolymer was increased. The results of this work provide an important information for the synthesis of this kind of materials by reactive extrusion.     

Crosslinking of partially neutralized liquid rubbers containing terminal and pendent carboxyl groups with anhydride and bisepoxide

Crosslinking of partially neutralized liquid rubbers containing terminal and pendent carboxyl groups with anhydride, and bisepoxide was investigated by the carboxyl–anhydride-epoxide reaction. The partially neturalized liquid rubbers were prepared by the partial neutralization with MgO and CaO from a butadiene (BD)–acrylonitrile (AN) copolymer (Hycar CTBNX 1300X9) with the functionality of 2.4. Bisphenol-A diglycidyl ether (BADG) was the bisepoxide used, and hexahydropthalic anhydride (HPA) was the anhydride used. The metal carboxylate groups in the system catalyzed the curing reaction. The metal-containing cured rubbers obtained showed considerably higher tensile strength than the previously reported metal-containing cured rubbers based on CTBN 1300XB (BD–AN copolymer) with the lower functionality of 1.8. In addition, the cured rubbers generally showed higher water resistance, and lower weight gains in benzene, dioxane, and n-hexane than the CTBN-series ones. Thermal behavior and stress relaxation are also discussed.     

聚酰胺6—聚醚嵌段共聚物增韧改性

以聚四氢呋喃醚为软段制备大分子活化剂，引发己内酰胺阴离子聚合，合成了聚酰胺６－聚醚嵌段共聚物，并考察大分子活化剂种类、用量对聚合物力学性能的影响。结果表明，所得制品在保持一定强度、硬度的条件下，冲击性能可大幅度提高，取的了较好的增韧效果。     

Synthesis and characterization of amine‐functionalized amphiphilic block copolymers based on poly(ethylene glycol) and poly(caprolactone)

A series of amine‐functionalized block copolymers, poly(caprolactone)‐block‐poly(ethylene glycol) (PCL‐b‐PEG), were synthesized by ring‐opening bulk polymerization (ROP) of ε‐caprolactone (ε‐CL) initiated through the hydroxyl end of the amino poly(ethylene glycol) (PEG) used as a macroinitiator in the presence of stannous 2‐ethylhexonoate [Sn(Oct)₂]. The polymerization and end functionality of the polymer were studied by different physicochemical techniques (¹H NMR, Fourier transform infrared and X‐ray photoelectron spectroscopy, gel permeation chromatography and thermogravimetric analysis). Thermal, crystalline and mechanical properties of the polymer were thoroughly analyzed using differential scanning calorimetry, wide‐angle X‐ray diffractometry and tensile testing, respectively. The results showed a linear improvement in crystallinity and mechanical properties of the polymer with the content of PEG. Thus the synthesized functional polymers can be used as excellent biomaterials for the delivery of polyanions, as well as macroinitiators for the synthesis of A–B–C‐type block copolymers. Copyright © 2006 Society of Chemical Industry     

Kinetic investigation and regularities during the synthesis of Poly(ε-caprolactam-co-ε-caprolactone) and Poly(ε-caprolactam-co-δ-valerolactone) biodegradable copolymers

Summary Large diversity of tailor-made poly[(ε-caprolactam)-co-(ε-caprolactone)] P[(CLA)-co-(CLO)] and poly[(ε-caprolactam)-co-(δ-valerolactone)] P[(CLA)-co-(VLO)] copolymers have been obtained via activated anionic polymerization of ε-caprolactam (CLA) with sodium caprolactam (NaCL) as a basic initiator. In the present study several poly(ε-caprolactones) (PCLOs) and poly(δ-valerolactone) polyols were employed as effective bifunctional polymeric activators (PACs) and suitable comonomers of CLA. The obtained poly(esteramides) PEAS were isolated and their structure was confirmed by the ¹H NMR and FTIR spectroscopy. The influence of the molecular weight and type of the PACs, the CLA/PAC ratio and polymerization conditions on the conversion, intrinsic viscosity and polymerization kinetic was explored. The results demonstrated that the use of the PACs reduces the polymerization time to several minutes and polymerization process proceeds without induction period at low energy of activation and high yield of copolymers. Evaluation of the PACs activity and the activation energy confirmed that the PACs are highly active compounds efficient to CLA features modification.     

Synthesis and characterization of nylon-polyisobutylenenylon triblock copolymers

Nylon-6-polyisobutylene-nylon-6 triblock copolymers have been synthesized by converting telechelic polyisobutylene diols to , -diisocyanate polyisobutylenes and using these macroactivators, in conjunction with strong base, to induce the subsequent anionic polymerization of -caprolactam. Pure block copolymer was obtained by suitable sequential extraction. Products were characterized by composition, molecular weight and DSC.     

Compatibilization efficiency of styrene–butadiene triblock copolymers in polystyrene–polypropylene blends with varying compositions

The compatibilization efficiency of two styrene‐butadiene‐styrene triblock copolymers with short (SB1) and long (SB2) styrene blocks was studied in polystyrene (PS)–polypropylene (PP) blends of composition 20, 50, and 80 wt % PS. The supramolecular structure of the blends was determined by small‐angle X‐ray scattering, and the morphology was studied with transmission electron microscopy and scanning electron microscopy. Structural changes in both the uncompatibilized and compatibilized blends were correlated with the values of tensile impact strength of these blends. Even though the compatibilization mechanisms were different in blends with SB1 and SB2, the addition of the block copolymers to the PS–PP 4/1 and PS–PP 1/4 blends led to similar structures and improved the mechanical properties in the same way. These block copolymers had a very slight effect on the impact strength in PS–PP 1/1 blends, exhibiting a nearly cocontinuous phase morphology. The strong migration of SB2 copolymers to the interface and of SB1 copolymers away from the interface were detected during the annealing of compatibilized PS–PP 4/1 blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2431–2441, 2004     

Morphological and Physical Properties of Triblock Copolymers of Methyl Methacrylate and 2‐Ethylhexyl Methacrylate

Summary: Triblock copolymers of methyl methacrylate (MMA) and 2‐ethylhexyl methacrylate (EHMA) [that is, poly(MMA–EHMA–MMA)] were prepared by an emulsion atom‐transfer radical polymerization. The relationships of their structural, morphological, and physical properties were investigated. The latex particles had core‐shell morphologies and the block copolymers experienced phase separation. Small latex particles with a low number of cores could deform and wet silicon‐wafer surfaces, but the deformation of large latex particles was restricted by the internal two‐phase morphology of the particles. Latex casting produced continuous pinhole‐free films, in which hard poly(MMA) (PMMA) cores of different latex particles merged and provided interparticle connections. The morphology of solution‐cast films depended on block composition, solvent type, and film thickness. For all the prepared polymer samples, thick films cast in toluene had poly(EHMA) (PEHMA) materials at air surface, whereas those cast in tetrahydrofuran had a sponge‐like PMMA surface structure. Thin toluene‐cast films from P(MMA–EHMA–MMA) with the block degrees of polymerization ( ) 200–930–200 showed spherical PMMA domains and those from 380–930–380 yielded a protruded worm‐like PMMA structure. The copolymer materials were coated on a glass surface for peeling tests. The films gave good hot‐melt adhesion properties when the of the PEHMA block was over 600. The peeling strength depended on the lengths of both PEHMA and PMMA blocks. The P(MMA–EHMA–MMA) sample with of 310–930–310 yielded the highest peeling strength of 7.4 kgf · inch^?1. The developed material is demonstrated to be a good candidate for a solvent‐free, hot‐melt, pressure‐sensitive adhesives for special‐purpose applications such as medical tapes and labels.

     

Synthesis and characterization of PBMA‐b‐PDMS‐b‐PBMA copolymers by atom transfer radical polymerization

Poly(butyl methylacrylate)–b–poly(dimethylsiloxane)–b–poly(butyl methylacrylate) (PBMA–b–PDMS–b–PBMA) triblock copolymers were synthesized by atom transfer radical polymerization (ATRP). The reaction of α,ω‐dichloride PDMS with 2′‐hydroxyethyl‐2‐bromo‐2‐methylpropanoate gave suitable macroinitiators for the ATRP of BMA. The latter procedure was carried out at 110°C in a phenyl ether solution with CuCl and 4,4′‐di (5‐nonyl)‐2,2′‐bipyridine (dNbpy) as the catalyzing system. The polymerization was controllable, with the increase of the monomer conversion, there was a nearly linear increase of molecular weight and a decrease of polydispersity in the process of the polymerization, and the rate of the polymerization was first‐order with respect to monomer conversion. The block copolymers were characterized with IR and ¹H‐NMR and differential scanning calorimetry. The effects of macroinitiator concentration, catalyst concentration, and temperature on the polymerization were also investigated. Thermodynamic data and activation parameters for the ATRP were reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 532–538, 2004     

Synthesis and properties of liquid‐ crystalline triblock copolymers by ATRP,having electron‐transporting thiadiazole unit

ABA‐type block copolymers composed of 2,5‐diphenyl‐1,3,4‐thiadiazole (DPTD) oligoester and poly(methyl methacrylate) (PMMA) segments (M_n = 16 200 and 23 000) were synthesized by atom‐transfer radical polymerization and their liquid‐crystalline (LC) and photoluminescence (PL) properties were examined. The structures of block copolymers were identified by Fourier transform infrared and ¹H NMR spectroscopies. Differential scanning calorimetry measurement, polarizing microscopy observation and wide‐angle X‐ray analysis revealed that the block copolymers form thermotropic LC phase (smectic C) independent of molecular weights of PMMA segments, but a model polymer (PMMA segments having the DPTD unit in the central part) has no LC melt. Solution and solid‐state PL spectra indicated that all the block copolymers display blue emission arising from the DPTD unit. Their quantum yields are 17–21%, which increase with the PMMA chain lengths. The block copolymers have good aligned structures in the LC states, but their order parameter (S) values in sheared LC states were lower than those in the sheared LC compounds. The PL properties in the LC states were independent of the LC aligned structures. Cyclic voltammetry measurements showed that these block copolymers have deep HOMO levels compared with polymers composed of oxadiazole rings. Copyright © 2007 Society of Chemical Industry