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.     

Functionalization of poly(ε-caprolactone) by pendant hydroxyl, carboxylic acid and epoxide groups by atom transfer radical addition

A straightforward strategy is proposed for grafting hydroxyl, carboxylic acid and epoxide groups along poly(ε-caprolactone) chains. Statistical copolymerization of ε-caprolactone (εCL) with α-chloro-ε-caprolactone (αClεCL) has been initiated by 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP), followed by the atom transfer radical addition (ATRA) of but-3-en-1-ol, vinylacetic acid and 1,2-epoxyhex-5-ene, respectively, onto the α-chloro units of a poly(αClεCL-co-εCL) copolymer. αClεCL is easily prepared by the Baeyer-Villiger oxidation of 2-chlorocyclohexanone. The influence of the experimental conditions, i.e. temperature, solvent, catalyst, on the grafting yield has been discussed. Because ATRA is tolerant of the investigated functional groups, no protection/deprotection reaction is required, which is a major advantage of the method.     

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).     

Synthesis,structure and behavior of new polycaprolactam copolymers based on poly (ethylene oxide)–poly (propylene oxide)–poly (ethylene oxide) macroactivators derived from Pluronic block copolymers

Novel series of poly (CL–co–Pluronic) polymers were successfully synthesized in situ by ring-opening polymerization (ROP) of ε-caprolactam (ε-CL). The copolymerization was activated by new type macroactivators (MAs) based on hydroxyl-terminated poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) [PEO-PPO-PEO] triblock copolymers, known under the trade name Pluronic^®. Toluene-2,4-diisocyanate (TDI) was used to obtain the isocyanate-terminated Pluronic prepolymers. The corresponding MAs were synthesized in situ with an N-carbamoyllactam structure. As an initiator of the copolymerization processes was used sodium lactamate (NaCL). To confirm the influence over the copolymerization process, microstructure, composition and molecular weight of the polymeric products two new types MAs based on Pluronic (P123 and F68) have been varied from 2 to 10 wt.% (vs. the monomer ε-CL). The structure of the both Pluronic based macroactivators (MAs) and accordingly obtained two series poly (CL-co-Pluronic) polymers were confirmed by ¹H NMR and FT-IR analyses. Additionally, the structure, molecular weight, physicomechanical behavior, thermal stability and morphology of the new synthesized poly (CL–co–Pluronic) polymers have been investigated by Differential Scanning Calorimetry (DSC), Wide-Angle X-ray Diffraction (WAXD), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) analysis.     

天然氨基酸作用下ε-己内酰胺/ε-己内酯的共聚反应

文章研究了天然氨基酸作用下ε-己内酰胺的开环聚合及其与ε-己内酯的共聚反应。结果显示:中性、酸性、碱性等三类氨基酸中,中性两官能团氨基酸作用下ε-己内酰胺的开环聚合反应可以进行。当ε-己内酰胺与L-苯丙氨酸摩尔比等于100,体系在220℃反应48h后,得到粘均分子量为15700g/mol的聚(ε-己内酰胺)。天然氨基酸作用下ε-己内酯和ε-己内酰胺的共聚也可以发生,聚(ε-己内酰胺-co-ε-己内酯)的结构通过GPC,1H-NMR和FT-IR得到证实。     

Rate of the activated anionic polymerisation of ε-caprolactam onto an isocyanate bearing polypropylene in the melt

This paper concerns the rate of the activated anionic polymerisation of ε-caprolactam (CL) onto 3-isopropenyl-α,α-dimethylbenzyl isocyanate bearing PP (PP-g-TMI) in the melt to form a graft copolymer with PP as backbone and PA6 as grafts. The polymerisation was catalysed by sodium ε-caprolactam (NaCL). The PP-g-TMI/NaCL/CL polymerisation system being heterogeneous, the polymerisation was carried out in a batch mixer. Emphasis was placed on the effects of temperature and the concentrations of NaCL and the isocyanate group in the form of PP-g-TMI on the polymerisation rate. Results suggested that if the polymerisation is to be carried out by a reactive extrusion process whose mean residence time is less than a few minutes, it is recommended that the polymerisation temperature be higher than 220 °C. Moreover, the molar ratio between NaCL and CL should be higher than 0.5 and at the same time that between the isocyanate group in the form of PP-g-TMI and NaCL, should be smaller than 4.     

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.     

A-B-A-Triblock and multiblock copolyesters prepared from ε-caprolactone, glycolide and l-lactide by means of bismuth subsalicylate

Bismuth (III) subsalicylate, a commercial drug, was used as catalyst for 1,4-butanediol-initiated copolymerizations of ε-caprolactone (εCL) and glycolide (GL). Telechelic copolyesters having two OH-endgroups and predominantly alternating sequences were obtained. These copolyesters are amorphous with glass transition temperatures (T_gs) below −30 °C. In a second series of polymerizations, in situ chain extension with l-lactide (LLA) was performed, whereby A-B-A triblock copolymers were obtained without significant transesterification between A- and B-blocks. Finally, these A-B-A triblock copolymers were transformed into multiblock copolymers by chain extension with 1,6-hexamethylene diisocyanate. The block copolymers were characterized by ¹H and ¹³C NMR spectroscopy, by viscosity, SEC and DSC measurements.     

Novel poly(ε-caprolactone)s bearing amino groups: Synthesis,characterization and biotinylation

A novel functional ε-caprolactone monomer containing protected amino groups, γ-(carbamic acid benzyl ester)-ε-caprolactone (γCABεCL), was successfully synthesized. A series of copolymers [poly(CL-co-CABCL)] were prepared by ring-opening polymerization of ε-caprolactone (CL) and γCABεCL in bulk using tin (II)-2-ethylhexanoate [Sn(Oct)₂] as catalyst. The morphology of the copolymers changed from semi-crystalline to amorphous with increasing γCABεCL monomer content. They were further converted into deprotected copolymers [poly(CL-co-ACL)] with free amino groups by hydrogenolysis in the presence of Pd/C. After deprotection, the free amino groups on the copolymer were further modified with biotin. The monomer and the corresponding copolymers were characterized by ¹H NMR, ¹³C NMR, FT-IR, mass, GPC and DSC analysis. The obtained data have confirmed the desired monomer and copolymer structures.     

Determination of the residual monomer concentration of ε-caprolactam in polyamide-6 using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy gas analysis

For the anionic polymerization of ε-caprolactam to polyamide-6 the residual monomer concentration in the final polymer is an important characteristic. To determine this residual ε-caprolactam monomer concentration, a fast and fail-safe method was developed, which couples thermogravimetric analysis (TGA) with Fourier transform infrared spectroscopy (FTIR) gas analysis. FTIR allows an identification of the types of gasses released during heat treatment. Calibration of the infrared absorbance of ε-caprolactam and the corresponding mass loss in TGA allows a quantitative evaluation of the ε-caprolactam monomer release. Low-heating rates and powdery samples guarantee high-precision measurements.     

Degradable poly(ester-ether urethane)s derived of AB2 miktoarm star copolymer poly(ethylene glycol-(ε-caprolactone)2) diol: Synthesis,characterization and degradation

Four different miktoarm star copolymers poly(ethylene glycol-(ε-caprolactone)₂) diol [PEG-PCL₂] were obtained using α-diol-ω-methoxy poly(ethylene glycol) [MPEG-(OH)₂] as macroinitiator/chain transfer agent in the ring opening polymerization (ROP) of ε-caprolactone (CL) catalyzed by tin(II) 2-ethylhexanoate [Sn(Oct)₂]. PEG-PCL₂ and 1,6-hexamethylene diisocyanate (HDI) were used as precursors of a new family of poly(ester-ether urethane)s PEUs. PEUs films were characterized by FT-IR, DSC, mechanical properties, water absorption, hydrolytic degradation and SEM.     

Synthesis, characterization and thermal properties of hexaarmed star-shaped poly(ε-caprolactone)-b-poly(d,l-lactide-co-glycolide) initiated with hydroxyl-terminated cyclotriphosphazene

Hexakis[p-(hydroxymethyl)phenoxy]cyclotriphosphazene was prepared by the reaction of hexachlorocycltriphosphaneze with the sodium salt of 4-hydroxybenzaldehyde and subsequent reduction of aldehyde groups to alcohol groups by using sodium borohydride. Hexaarmed star-shaped hydroxyl-terminated poly(ε-caprolactone) (PCL) were successfully synthesized via ring-opening polymerization of ε-caprolactone (CL) with the above hydroxyl-terminated cyclotriphosphazene initiator and stannous octoate catalyst in bulk. The number-average molecular weight of PCL linearly increased with the molar ratio of monomer to initiator. The star-shaped PCL with hydroxy end groups could be used as a macroinitiator for block copolymerization with d,l-lactide (d,l-LA) and glycolide (GA) using stannous octoate catalyst. IR, ¹H NMR and GPC analysis showed the star-block copolymers were successfully synthesized and the molecular weights and the unit composition of the star-shaped block copolymers were controlled by the molar ratios of d,l-LA and GA monomers to CL. The copolymer presented a two-phase structure, namely, PCL crystalline and d,l-LAGA amorphous domains, which made the copolymer different from linear PCL and star-shaped PCL in crystallinity and thermal behaviors.     

Structural investigations of the poly(ε-caprolactam)-urea inclusion compound

An interesting inclusion compound (IC) between guest poly(ε-caprolactam) (PεCL) and host urea was successfully obtained, for the first time, by co-crystallization from their common solution. X-ray diffraction, infrared spectroscopy and differential scanning calorimetry have been utilized for a detailed structural investigation of PεCL-urea IC (U IC) crystals. The results were compared with those obtained for well-known structures of the hexagonal polyethylene-U IC, the trigonal polyethylene oxide-U IC and the ‘large tetragonal’ poly(propylene)-U IC. The structure of PεCL-U IC reconfirms that the urea host molecules may crystallize, even in the presence of a rather slim polymer guest, into an IC with a lattice channel diameter of more than 5.25 Å.     

Synthesis and enzymatic degradation of poly(ε-caprolactone-co-ethylene carbonate-co-ethylene oxide) copolymer

Poly(ε-caprolactone-co-ethylene carbonate-co-ethylene oxide) (CL-co-EC-co-EO) copolymer was synthesized via ring-opening copolymerization of ε-caprolactone (CL) and 1,3-dioxolan-2-one with a metal-free phosphazene catalyst (t-BuP₄). The monomer conversion and molecular weight in CL-co-EC-co-EO copolymer were characterized by nuclear magnetic resonance and gel permeation chromatography, respectively. Moreover crystallization behavior of CL-co-EC-co-EO copolymer was investigated by differential scanning calorimeter and wide-angle X-ray diffraction. The enzymatic degradation of the copolymer has been investigated by quartz crystal microbalance with dissipation. Our studies demonstrate that as PCL content in the copolymer decreases, the degree of crystallinity and crystal size decrease, while the enzymatic degradation rate increases. The copolymer exhibits layer-by-layer degradation.     

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.     

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.     

螺杆构型对反应挤出制备聚乙烯/聚酰胺6原位合金的影响

以己内酰胺（CL）、高密度聚乙烯(PE-HD)、马来酸酐接枝高密度聚乙烯（PE-HD-g-MAH）为主要原料,采用反应挤出法制备PE-HD /聚酰胺6（PA6）原位合金,研究螺杆构型对PE-HD/PA6原位合金制备的影响。研究发现,停留时间长的螺杆构型,其对应的原位合金中CL单体转化率较高;在3种螺杆构型中,带有大导程拉伸元件的螺杆,所制备的原位合金中分散相PA6的粒径最小,其原因在于CL单体在PE-HD中的初始分散状态对合金中分散相PA6的粒径有直接影响,而大导程拉伸元件更有利于CL在PE-HD基体中的破碎与分散。     

A novel approach to RE–OR bond from in situ reaction of rare earth triflates and sodium alkoxides: A versatile catalyst for living ring-opening polymerization of ε-caprolactone

A series of rare earth triflates (RE(OTf)₃, RE = Sc, Y and Lu) were used for the first time as moisture-stable precursors to generate rare earth alkoxide complexes through an in situ reaction with sodium alkoxides (NaOR) in tetrahydrofuran. ¹H NMR and ¹³C NMR results confirmed the fast ligands exchange process and the formation of rare earth–oxygen (RE–OR) bond. The in situ formed catalysts displayed high reactivity toward living ring-opening polymerization (ROP) of ε-caprolactone (CL). For instance, Lu(OTf)₃/sodium isopropoxide (NaOⁱPr)-catalyzed ROP of CL with the [CL]₀/[NaOⁱPr]₀/[Lu(OTf)₃]₀ feeding ratio of 300/3/1 produced poly(ε-caprolactone) (PCL) with controlled molecular weight (M_n,exp = 11.9 kDa vs M_n,theo = 11.8 kDa) and narrow polydispersity (PDI) of 1.08 within 3 min at 25 °C. The kinetic studies and chain extension confirmed the controlled/living nature for the Lu(OTf)₃/NaOⁱPr-catalyzed ROP of CL. In addition, end-functionalized PCLs bearing vinyl or alkynyl group with narrow PDIs were obtained by using functional sodium alkoxides in the presence of Lu(OTf)₃. ¹H NMR and MALDI-ToF MS analyses of the obtained PCLs clearly indicated the presence of the residue of OR groups at the chain ends. A coordination–insertion polymerization mechanism was proposed including a fast ligand exchange between Lu(OTf)₃ and NaOR giving the respective lutetium alkoxide complexes, and a CL insertion into RE–OR bond via acyl-oxygen cleavage.     

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.     

已内酰胺水解聚合过程中的化学反应

简要介绍PA6聚合物制备方法,对己内酰胺水解聚合过程中的开环、缩聚和加聚三个主要反应、酰胺交换反应、分子量调节剂的反应及环聚物形成、氧化、去氨化和去羧基化等副反应作了系统综述.在此基础上,提出了PA6聚合反应工程研究中尚有待开展的几点建议.