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.     

Die polymerisation der lactame VI. Die copolymerisation von 6-caprolactam und 8-capryllactam

The process of incorporating 6-caprolactam and 8-capryllactam into polymer chains was studied during the hydrolytic, cationic, and anionic copolymerization in the case of equimolar ratio of the above mentioned monomers. At the beginning of the hydrolytic copolymerization at temperatures between 200 and 260°C, 6-caprolactam was more rapidly incorporated into the chains. Decreasing temperature led to a decrease in the total rate of polymerization with increasing difference between rates of incorporating the two components. Contrary to this, at the initial stage of the cationic copolymerization, the incorporation of 8-capryllactam was faster by orders of magnitude than that of 6-caprolactam, the changes of the copolymer composition being independent of temperature. Under the conditions of interest, in the course of the anionic copolymerization the two monomers were characterized with the same rates of incorporation into the polymer chains. Different melting points of products separated at various stages of the copolymerization process corresponded to the above mentioned differences in rates of incorporating individual monomers into polymer chains when different reaction mechanisms were employed.     

Die Polymerisation der Lactame. XV. Die Polymerisation der Lactame in Gegenwart von N-Benzoyllactamen und Pentamethylguanidin

The catalytic system pentamethylguanidine/N-acyllactam is able to induce the polymerization of lactams. Whereas in the case of 2-pyrrolidone the course or the process is similar to polymerizations initiated with alkali salts of this lactam, except for that it is remarkably more moderate, in the case of 6-caprolactam and 8-caprylolactam it is characterized by an induction period that is not typical for activated anionic polymerizations of these lactams. At 175°C the rate of polymerization of 8-caprylolactam is by more than one order of magnitude higher than that for 6-caprolactam, and in both of them the process is more moderate than in case of activated polymerizations of these lactams initiated by their alkali salts. On the basis of conductivity measurements in the case of 2-pyrrolidone it is possible to assume an anionic mechanism of the polymerization.     

Graft copolymers of poly(methyl methacrylate) and polyamide-6 via in situ anionic polymerization of ε-caprolactam and their properties

Graft copolymers of poly(methyl methacrylate) and polyamide-6 (PMMA-g–PA6) were investigated via in situ anionic polymerization of ε-caprolactam, using PMMA precursors with N-carbamated caprolactam pendants (PMMA–CCL) as macroactivators and sodium caprolactamate as catalyst. Three grades of PMMA–CCLs obtained by free radical copolymerization were used for synthesizing the PMMA-g–PA6 copolymers with different PMMA content. The resulting graft copolymer was characterized by Fourier-transform infrared spectroscopy and selective extraction. Scanning electron microscopy is used to clarify the phase morphology of obtained polymer by fracture surface. The thermal property, crystallinity and dimensional stability of graft copolymer were studied using differential scanning calorimetry, X-ray diffraction and water absorption measurement. The results show the T_g of graft copolymer is higher than that of neat PA6, but the onset and peak points of graft copolymer melting point are shifted to lower temperature. The percentage crystallinity and water absorption of PMMA-g–PA6 copolymer decrease with increasing PMMA content, but the crystal structure of PA6 is scarcely affected by the presence of PMMA. Graft copolymers have improved dimensional stabilities relative to neat PA6. Upon the incorporation of 19.9 wt% PMMA into PA6, the water absorption of PMMA-g–PA6 copolymer has been reduced from 4.8 for neat PA6 to 2.1%.     

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, 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, 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).     

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.     

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.     

Emulsion copolymerization of tetrafluoroethylene with ω‐chlorotetrafluoroethyltrifluorovinyl ether and the synthesized copolymer properties

Emulsion copolymerization of ω‐chlorotetrafluoroethyltrifluorovinyl ether (Cl(CF₂)₂OCF = CF₂ (FVE)) with tetrafluoroethylene (CF₂ = CF₂ (TFE)) was investigated at various monomer ratios. The copolymerization rate is below the rate of TFE homopolymerization and the copolymerization kinetics depends on the FVE content in the reaction medium. The copolymer composition is very similar if the FVE content in monomer mixture is ≤2.5 mol %. However, the percent amount of FVE in the copolymer, the copolymerization rate, and molecular mass of synthesized copolymers decrease noticeably with increase in the FVE content in the monomer mixture. The constants of copolymerization are r₁= 2.8 (TFE) and r₂ = 0.03 (FVE). The copolymer is a statistical polymer consisting of TFE blocks and individual FVE molecules between the blocks. The average molecular mass of copolymers is significantly less than that of the TFE homopolymer (PTFE) synthesized at the same conditions. The morphologies of PTFE and copolymer powders were investigated by thermomechanical analysis and are not similar. The copolymer has a completely amorphous diblock morphology depending on the FVE content. The introduction of FVE molecules into the copolymer macromolecules is accompanied by reduction of the crystalline portion of copolymer. If the FVE content in copolymer is ≥3.5 mol %, the copolymer macromolecules completely lose the ability to form crystalline portions as a result of their amorphicity. The introduction of up to 2.4 mol % FVE into the copolymer macromolecules yields a highly thermostable and meltable copolymer which can be processed by using the industrial processes used widely for thermoplastics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The structure and physical properties of anionically polymerized nylon 6 crosslinked by bislactams

Crosslinked polyamides prepared by copolymerization of ?-caprolactam with bislactams under conditions of activated anionic polymerization proceeding adiabatically below their melting point show differences in physico-mechanical properties. Owing to varying copolymerization rates of bislactams, depending on the position of the connecting bridge of the bislactam in relation to the amido group, copolymers with different morphological structure are formed. The differences in the mechanical properties of the copolymers are explained on the basis of the differences in the morphological structure. This explanation is supported by results obtained by measuring the thermal and dynamic properties.     

共聚改性MC尼龙的制备和DSC分析

以氢氧化钠为催化剂,N 乙酰基己内酰胺为活化剂,催化剂和活化剂物质的量与反应单体物质的量之比均为1∶400,聚合起始温度为130℃,在绝热条件下,通过活化阴离子共聚制得了增韧MC尼龙共聚体。通过示差扫描量热分析测定共聚物熔点和结晶相含量,吸热熔融峰表明改性MC尼龙是无规共聚物,共聚导致了制品结晶度下降,结晶的特点是熔点的宽分布、不规则生长以及高浓度无定形区域对结晶存在干扰。     

Controlled synthesis of crosslinked polyamide 6 using a bis-monomer derived from cyclized lysine

The controlled synthesis of polyamide 6 chemical networks by anionic ring-opening copolymerization of ε-caprolactam (CL) with synthesized bis-ε-caprolactam derived from α-amino-ε-caprolactam, i.e. N-functionalized α-amino-ε-caprolactam bis-monomers, using sodium ε-caprolactamate as an initiator and hexamethylene-1,6-dicarbamoylcaprolactam as di-functional fast activator was examined in bulk at 140 °C. An urea-based bis-monomer and CL were first shown to copolymerize with a decreasing polymerization rate due to side reactions. On the contrary, quantitative copolymerization of CL with various amounts of bis-N(2-oxo-3-azepanyl)-1,6-tetramethylenediamide, an amide-based bis-monomer, leads to fast kinetics similar to the homopolymerization of CL. Crosslinked PA6 with network exhibiting elastic or viscoelastic behaviors, depending on the amount of crosslinker, were observed and characterized by swelling in hexafluoroisopropanol, dynamic mechanical analysis and rheology measurements. Crystallinity and swelling were shown to decrease with the increasing content of the crosslinking agent.     

Synthesis and characterization of styrene–N-butyl maleimide copolymers using iniferters containing thiyl end groups

The radical homopolymerization of styrene or copolymerization of styrene (S) with N-butyl maleimide (I) initiated by tetraethylthiuram disulfide was used to prepare macroinitiators having thiyl end groups. The S–I copolymers from the feeds containing 30–70 mol % I showed approximately alternating composition. The rate of copolymerization and molecular weights decreased with increasing maleimide derivative concentration in the feed; homopolymerization of I alone did not proceed. The macroinitiators served for synthesis of further S–I copolymers. Using polystyrene macroinitiator and the S–I copolymer with thiyl end groups in the polymerization of S–I mixture and styrene, respectively, the copolymers containing blocks of both polystyrene and alternating S–I copolymer were obtained. The copolymerization of S–I mixture initiated with the S–I copolymer bearing thiyl end groups led to the extension of macroinitiator chains by the blocks of alternating copolymer. The presence of the blocks in the polymer products was corroborated using elemental analysis, size exclusion chromatography, and differential scanning calorimetry. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 755–762, 1998     

Facile synthesis of oxidative copolymers from aminoquinoline and anisidine

Oxidative copolymerization of 8-aminoquinoline (AQ) and o-anisidine (AS) using ammonium persulfate as oxidant was studied under various polymerization conditions and fine and uniform copolymer particles of several micrometers, determined by laser particle size and atomic force microscopic analyses, were synthesized simply. The polymerization yield, molecular weight, solubility, electroconductivity, and thermostability of the copolymers were systematically studied by changing the comonomer ratio, polymerization temperature, monomer/oxidant ratio, and acidic medium. Single chain configuration of the copolymers with various AQ/AS ratios was simulated and well related to the intrinsic viscosity. The macromolecular structure of the resulting copolymers was wholly characterized by elementary analysis, IR, UV-vis, high-resolution ¹H NMR, and solid-state high-resolution ¹³C NMR. The results show that the oxidative copolymerization of AQ and AS is exothermic. All copolymers are totally soluble in H₂SO₄, HCOOH, m-cresol but their solubility in other solvents depends significantly on the comonomer ratio, and also on the polymerization conditions. The oxidative polymer obtained is a real copolymer containing AQ and AS units rather than a mixture of two homopolymers. The AQ content calculated based on the ¹H NMR spectra of the copolymers is slightly higher than feed AQ content when feed AQ content is lower than 70 mol%. However, the AQ content calculated based on the ¹³C NMR and elementary analyses is lower than the feed AQ content when the AQ feed content is higher than 50 mol%. A peculiar dependency of molecular weight and electroconductivity of the copolymers on the AQ/AS ratio was observed. The decomposition temperature of the copolymers rises with increasing AQ content. Therefore, the thermostability of the copolymers increases with increasing AQ content due to its high aromaticity.     

The copolymerization of methyl methacrylate and isoprene in the presence of ethyl aluminium sesquichloride: role of monomer complexes

The kinetics of the spontaneous copolymerization of methyl methacrylate and isoprene in the presence of ethyl aluminium sesquichloride in toluene and at temperatures between 0° and 40°C have been investigated. Irreproducible fast initial rates of copolymerization are followed by slower reproducible rates. The structures of the copolymer and the accompanying Diels-Alder adduct have been determined by ¹H and ¹³C n.m.r.; the copolymers produced under a wide range of conditions are equimolar and highly alternating. The concentrations of various binary and ternary complexes have been assessed through ¹H n.m.r. chemical shift measurements; it is shown that the mechanism of copolymerization cannot involve simply the effective homopolymerization of ternary isoprene-methyl methacrylate-ethyl aluminium sesquichloride complexes.     

Struktur und eigenschaften von ABS-polymeren. III.. Charakterisierung der pfropfcopolymerisate von styrol-acrylnitril auf polybutadien durch oxydativen abbau

Graft copolymers of styrene-acrylonitrile on polybutadiene are isolated from the mixture with styrene-acrylonitrile copolymer formed during the graft copolymerization and are subjected to an oxidative degradation with potassium permanganate. The styrene-acrylonitrile copolymer grafted onto the polybutadiene can be isolated from the oxidation residue; it is, hence, accessible to further investigations. By blank runs it was verified that the styrene-acrylonitrile copolym er is not degraded under the oxidative conditions chosen. The increased content in carboxyl groups of the styrene-acrylonitrile copolymer isolated after oxidation of the polybutadiene grafted with it is attributed to fragments of the degraded graft basis.     

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.     

Die polymerisation der lactame XIV. Einfluß des hexamethylguanidiniumchlorides auf die aktivierte anionische polymerisation der lactame

It was proved that hexamethylguanidiniumchloride (HMGC) exhibited a pronounced accelerating effect on the activated anionic polymerization of 2-pyrrolidone (40°C) and 6-caprolactam initiated by alkali metal salts of the corresponding lactams. The accelerating effect of HMGC was not specific for a certain type of alkali metal salt of lactams as initiator, it was proved that the effect is operative for polymerization of 6-caprolactam when using sodium or cesium salt of 6-caprolactam. It was proved that HMGC does not form growing centers under reaction conditions studied. The initial polymerization rate in the homogeneous phase is a linear function of square root of HMGC concentration at constant concentrations of initiator and activator. On the basis of this finding it was possible to suggest a plausible mechanism of HMGC influence on the polymerization process.     

The effect of chemical heterogeneity on the properties of statistical copolymers: the conductivity of poly(aniline‐co‐2‐bromoaniline)

Chemical heterogeneity can influence the properties of statistical copolymers. It is shown that any integral property of a copolymer will depend on the chemical heterogeneity if such a property is a non‐linear function of copolymer composition. This is illustrated by means of the conductivity of copolymers of aniline and 2‐bromoaniline. The monomer reactivity ratios of this monomer pair are r_A (aniline) = 0.94 and r_B (2‐bromoaniline) = 0.31. The dependence of conductivity on the copolymer composition is non‐linear. Consequently, the conductivity depends on the compositional distribution, ie on the extent of chemical heterogeneity. Heterogeneous high‐conversion copolymers have lower conductivity than corresponding relatively homogeneous low‐conversion copolymers. The change in the average copolymer composition with increasing conversion is demonstrated for a copolymerization mixture containing 30 mol% aniline. The conductivity decreases at the same time as the chemical heterogeneity of the copolymer develops. The change in the average copolymer composition alone cannot explain the observed conductivity decrease. The conductivity is dependent not only on average composition but also on the chemical composition distribution. Copyright © 2004 Society of Chemical Industry