Polymerization of lactams, 48. Autocopolymerization of 6-caprolactam with 12-dodecanelactam

The homo- and copolymerization of 6-caprolactam and 12-dodecanelactam was studied in the absence of an intentionally added initator. Both the polymerization and the copolymerization of an equimolar mixture of the monomers exhibited an induction period, the length of which was reduced with increasing temperature. Above 260°C, the polymers and copolymers of 6-caprolactam were not stable and their intrinsic viscosities as well as the polymer content decreased during long polymerization periods. On the other hand, insoluble products were formed in the homopolymerization of 12-dodecanelactam at temperatures of 300°C and higher. As much as 35 wt.-% of oligomers, predominantly cyclic ones, were formed in the initial stage of polymerization and copolymerization.     

Polymerization of lactams, 43. Hydrolytic copolymerization of 6-caprolactam with 12-dodecanelactam

The copolymerization of 6-caprolactam with 12-dodecanelactam with 2 mol-% 6-aminocaproic acid as the initiator was investigated at 260°C within a broad concentration range of both comonomers. With increasing content of 12-dodecanelactam in the initial mixture the equilibrium content of the copolymer increased and the rate of copolymerization decreased. In the initial stage of copolymerization 12-dodecanelactam disappeared very quickly from the initial mixture; it was not incorporated into the copolymer directly, but through oligomers, probably through a cyclic dimer. The effect of temperature on the copolymerization process was examined for an equimolar composition of the initial mixture. It was demonstrated that starting with the polymerization temperature of 260°C, the copolymers underwent degradation on long-termin heating. At 280°C, degradation occured already after 50 h of polymerization. The apparent activation energy of copolymerization, 62 kJ/mol, was calculated from the temperature dependence.     

Polymerization of lactams, 38. Copolymerization of 6-caprolactam with some of its non-homopolymerizing derivatives

It was demonstrated that non-homopolymerizing derivatives of 6-caprolactam: 7-cyclohexyl-1-aza-2-cycloheptanone (I) and 7-isopropyl-5-methyl-1-aza-2-cycloheptanone (II) were polymerizing with 6-caprolactam under conditions of the socalled hydrolytic polymerization. With its increasing content in the initial reaction mixture the copolymerization rate, the equilibrium content of the copolymer, and the reduced viscosity decreased. Lactam (I) was a more reactive comonomer in comparison with lactam (II).     

Polymerization of lactams, 49. Hydrolytic polymerization of 6-caprolactam in the presence of its cyclic dimer

The hydrolytic polymerization of 6-caprolactam has been studied at 260–280°C in the presence of 5, 10 and 15 mol-% of cyclic dimer of 6-caprolactam and 2 mol-% of 6-aminocaproic acid as an initiator. The content of monomer and cyclic oligomers, including pentamer, was determined by HPLC. It has been proved that the rate of polymerization decreases with increasing content of cyclic dimer in the initial mixture and the time required to attain the equilibrium content of polymer increases as much as by an order of magnitude. The cyclic dimer is incorporated into the polymer above all in the final reaction stage.     

Polymerization of lactams,XLI. Molecular characterization of linear and branched polycaprylolactam

Samples of linear polycaprylolactam have been prepared and fractionated, and the [η]-M_w relationship has been established in m-cresol. Statistically branched samples have been obtained by copolymerizing 8-caprylolactam with bislactams. The degree of branching as well as the branching ability of different bislactams are discussed and compared with the corresponding data for branched polycaprolactams.     

Polymerization of lactams, 96 anionic copolymerization of ε-caprolactam with ω-laurolactam

Poly[(ε-caprolactam)-co-(ω-laurolactam)] was prepared at two different experimental arrangements — pseudoadiabatically and isothermally. Polymerization activity of two initiators ε-caprolactam magnesium bromide (CLMgBr) or sodium salt of ε-caprolactam (CLNa) in combination with N-benzoyl-ε-caprolactam (BzCL) was compared. The copolymerizations were carried out in the whole concentration scale of both monomers and in the temperature range from 120 to 240 °C. Prepared materials were evaluated by means of polymer yield, DSC, DMA and WAXS. The results have shown fundamental differences between both initiators. Copolymers prepared by initiation with CLNa have random character, one melting endotherm and display one crystalline form opposite copolymers prepared by initiation with CLMgBr having heterogeneous character proved especially by two melting endotherms (∼140 and ∼210 °C) and two types of crystalline form (α and γ).     

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.     

Polymerization of lactams, 94. Formation of cyclic oligomers in anionic polymerization of 6-hexanelactam

HPLC analysis of the methanol-extractable fractions of polymers was used to study the formation of cyclic oligomers during the non-activated anionic polymerization of 6-hexanelactam initiated by sodium or magnesium salt of 6-hexanelactam and ethylmagnesium bromide at 190°C. It was demonstrated that the nature of the counterion of the substance which initiates the anionic polymerization has a crucial effect on the mechanism of the formation of the cyclic oligomers. It was proved that in the course of the 6-hexanelactam polymerization in presence of magnesium compounds, the cyclic oligomer formation is distinctly slower, as compared to the sodium 6-hexanelactam-initiated polymerization.     

Polymerization of lactams, 95 Preparation of polyesteramides by the anionic polymerization of ε-caprolactam in the presence of poly(ε-caprolactone)

Preparation of polyesteramides-poly[(ε-caprolactam)-co-(ε-caprolactone)]s by anionic polymerization of ε-caprolactam in the presence of poly(ε-caprolactone) at 150 °C was studied in this paper. ε-Caprolactam magnesium bromide was used as an initiator of polymerization and polymeric materials containing 5-25 wt% ε-caprolactone units were obtained. Thermal methods (DSC and DMA) were employed for characterization of poly[(ε-caprolactam)-co-(ε-caprolactone)]s and their mechanical properties were also evaluated. By introducing the activator with N-acyllactam structure, the polymerization rate increased and it was possible to carry out the polymerization at 110 °C. Mechanical properties of polyesteramides were influenced by both the content of ε-caprolactone units incorporated into copolymer and polymerization temperature. The mechanism of incorporation of poly(ε-caprolactone) is discussed. The results show that it is not possible to restrict exchange transacylation reactions, progressing in the course of polymerization, by kinetic tools.     

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.     

Die polymerisation der lactame XI. Die copolymerisation von 6-caprolactam mit 12-laurolactam

The course of the incorporation of 6-caprolactam and 12-laurolactam into polymer chains during the hydrolytic, cationic and anionic copolymerization for an equimolar ratio of the monomers was studied. During the hydrolytic copolymerization 6-caprolactam is incorporated more rapidly at 260, 230 or 200°C at the beginning of the polymerization process; the differences between incorporation rates of the lactams into the copolymer increase with decreasing temperature. During the cationic copolymerization the incorporation of 12-laurolactam is more rapid by orders of magnitude for the above temperatures at the beginning of the process. Changes in the composition of cationic copolymers as compared to the hydrolytic copolymers are independent of the temperature during the copolymerization. The anionic copolymerization is characterized by a more rapid incorporation of 6-caprolactam into the polymer chain. The differences in the polymerization activity of the two lactams decrease with increasing temperature of the anionic copolymerization. The described course of incorporation of individual monomers, with the various mechanisms of the polymerization, also corresponds to melting points of copolymers in accordance with their composition.     

The structure and physical properties of copolymers of lactams

Copolymers of caprolactam with caprylolactam and laurolactam were prepared by activated anionic copolymerization under adiabatic conditions, at an initial polymerization temperature of T₀ = 130°C. The drop of the crystalline phase content and changes of the copolymer morphological structure depending on the content of comonomers result in increasing toughness and deformability due to enhanced yielding ability. The dependences of the copolymer structure and properties on the concentration of comonomers are different for the two series of copolymers. This results from different courses of the polymerization and crystallization history as a consequence of a large difference between polymerization rates of caprylolactam and laurolactam.     

Morphology and Thermal Behavior of MCPA6/SAN Blends Prepared by Anionic Ring-Opening Polymerization of ε-caprolactam

Summary In this article, a series of blends of monomer casting polyamide 6 and styrene-co-acrylonitrile (MCPA6/SAN) were prepared by in situ anionic ring-opening polymerization of ε-caprolactam (CL). Their morphology and thermal behaviors were investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide-angle x-ray diffraction (WAXD), respectively. The SAN phase had much finer domain in MCPA6/SAN than that in the polyamide6/SAN (PA6/SAN) blends prepared by melt blending of PA6 and SAN. All the melting and crystallization parameters of MCPA6/SAN blends decreased gradually with the increase of SAN content, while the melting temperature was almost unchanged. These results were due to the hydrolysis reaction of SAN occurred during the anionic polymerization of ε-caprolactam (CL). In addition, WAXD results showed that only α crystal forms existed in the MCPA6/SAN blends.     

聚酰胺6-聚氨酯嵌段共聚物的合成及表征

以聚醚三元醇、二苯甲烷二异氰酸酯以及己内酰胺为单体,在碱性催化剂条件下,通过单体浇铸工艺合成聚酰胺6-聚氨酯(PA6-PU)嵌段共聚物.采用傅里叶变换红外光谱仪、差示扫描量热仪表征其结构与性能.结果表明,PA 6-PU嵌段共聚物的熔点下降,且具有两相结构.力学性能分析显示,PU组分的嵌入使共聚物的常温冲击强度南7.20 kJ/m2提高到42.76 kJ/m2,低温(-50℃)冲击强度由4.20 kJ/m2提高到15.14 kJ/m2.     

Dispersion copolymerization of polyoxyethylene macromonomer and styrene. Part 3. Molecular characterization of polystyrene-graft-polyoxyethylene copolymers

Graft copolymers (polystyrene-graft-polyoxyethylene) (PS-graft-PEO) were prepared by the dispersion copolymerization of methacryloyl-terminated polyoxyethylene macromonomer and styrene initiated by an oil-soluble initiator (dibenzoyl peroxide, DBP). The apparent molecular weights of graft copolymers measured by size exclusion chromatography in tetrahydrofuran were found to be proportional to the -0·8th power of DBP concentration. This reaction order supports the termination of growing radicals by a first order radical loss process. The molecular weight distribution estimated from the size exclusion chromatography (SEC) data was found to decrease slightly with DBP concentration and to drop rapidly with macromonomer concentration. This was attributed to chain transfer events and to the increase of particle number: the higher the particle number the lower the monomer concentration in the particles. The bulkiness of the macromonomer molecules and the high segment density around the propagating reaction loci hinder the incorporation of macromonomer molecules into a copolymer growing chain. ©1997 SCI     

Polymerization of Cyclic Monomers, 12

Summary: The radical polymerization of different substituted methyl 2‐(bicyclo[3.1.0]hex‐1‐yl) acrylates, 1a – f , was initiated by 2,2′‐azoisobutyronitrile (AIBN) at 65 °C in chlorobenzene. The radical homopolymerization of 1a – f occurred through the opening of the cyclopropane ring, and lead to polymers with number‐average molecular weights of 13 000 to 434 400 g · mol^?1 and glass transition temperatures between 77 and 121 °C. The monomers 1a – f showed a similar reactivity to MMA (in the copolymerization with MMA). Selected monomers were determined to be diluent monomers for dental filling composites and enable the preparation of composites that show a significantly reduced polymerization shrinkage, compared to composites based on dimethacrylate diluents.

     

Preparation of PS-g-PA6 copolymers by anionic polymerization of ε-caprolactam using PS precursors with N-carbamated caprolactam pendants as macroactivators

The graft copolymer of polystyrene and polyamide 6 (PS-g-PA6) was investigated by anionic polymerization of ε-caprolactam (CL), using the free radical copolymer of styrene and a kind of allyl monomer containing N-carbamated caprolactam group as macroactivator (PS-CCL). CL monomers were grafted onto PS-CCL backbone via initiating N-carbamated caprolactam (CCL) pendants along its backbone to form the graft copolymer in the presence of catalyst sodium caprolactamate. The macroactivator was characterized by Fourier-transform infrared spectroscopy and nuclear magnetic resonance, and the graft copolymer by the selective solvent extraction technique using methanol and chloroform as solvents. PS-g-PA6 copolymers with different PS content were synthesized to study the effect of PS on morphology, crystallinity, dimensional stability, and thermal properties, using scanning electron microscopy, X-ray diffraction, water absorption measurement, thermogravimetric analysis, and differential scanning calorimetry. The results show the percentage crystallinity of graft copolymer decreases with increasing PS content, but the addition of PS scarcely influences the crystalline structure of PA6. The graft copolymer has improved thermal properties and dimensional stability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymerization of lactams, 28. Effect of reaction conditions on the anionic polymerization of 2-pyrrolidone (part 5)

The effect of temperature, activator concentration, and polymerization time on the anionic polymerization of 2-pyrrolidone was studied using the method of statistical planning of the experiments. Sodium tert-butoxide or sodium dihydrido-bis(2-methoxyethoxy)aluminate was used as initiator; N-acetylpyrrolidone served as activator in both cases. Results obtained with both initiation systems were presented in the form of explicit mathematical equations.     

Molecular characterization of statistical copolymers: 1. Potential and limitations of full adsorption–desorption procedure in separation of statistical copolymers

Dynamic integral desorption isotherms for a series of poly(methyl methacrylate) homopolymers and poly(methyl methacrylate)–polystyrene statistical copolymers were measured. Nonporous silica was the full adsorption–desorption (FAD) column packing and various adsorption‐promoting and desorption‐promoting liquids were used. The aim of this study was to evaluate the applicability of the FAD approach for separation of statistical copolymers. The effects of the adsorbing liquid and desorbing liquid nature were demonstrated on the positions and shapes of desorption isotherms. The desorption isotherms also strongly depended on both (co)polymer molar mass and copolymer chemical composition. This indicates large fractionation potential of the FAD procedure. Simultaneously, the interference of both above parameters prevents the direct use of FAD for fractionation of the copolymers. It is anticipated that the fractionation and/or reconcentration potential of the FAD procedure can be very effectively utilized in combination of FAD with size‐exclusion chromatography and/or with gradient elution liquid adsorption chromatography. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 857–864, 2000