Synthesis and solution properties of alternating maleimide/styrene hyperbranched copolymers via controlled radical mechanism

Copolymerizations of (N,N‐diethyldithiocarbamyl)methylstyrene (inimer: DTCS) with maleimide (MI) were carried out under UV irradiation. DTCS monomers play an important role in this copolymerization system as an inimer that is capable of initiating radical polymerization of the vinyl group. Reactivity ratios (r₁ = 0.15 and r₂ = 0) were estimated by the curve‐fitting procedure (DTCS [M₁]; MI[M₂]). These reactivities show strong alternation, and the propagating copolymer radicals proceed with homopolymerization of 1:1 complexes formed between the donor and acceptor monomers. These alternating copolymers exhibit highly branched structure and are actually hyperbranched copolymers. The compact nature of the hyperbranched molecules was demonstrated by comparison of their dilute‐solution properties with those of the linear analogues. The hyperbranched macromolecules behave as single, well‐separated molecules (even in good solvent) and as hard spheres. Copyright © 2003 Society of Chemical Industry     

Microwave‐assisted one‐pot copolymerization of cyclic monomers and ethyl diazoacetate

The present contribution describes an innovation in the copolymerization of cyclic monomers, ε‐caprolactam (ε‐CL) and 2,2‐dimethyltrimethylene carbonate (DTC), with ethyl diazoacetate (EDA). The characterizations of the obtained copolymers, poly(EA‐ran‐EDA‐ran‐ε‐CL) and poly(EA‐ran‐EDA‐ran‐DTC) (where EA refers to the ethyl acetate group from EDA after nitrogen release), were performed using ¹H NMR and ¹³C NMR spectroscopies and size exclusion chromatography. Under optimized conditions, the copolymer of ε‐CL with EDA possessing a number‐average molar mass (M_n) of 1300 g mol^?1 and dispersity of 2.12 as well as that of DTC with EDA with M_n of 8000 g mol^?1 and dispersity of 1.47 were obtained. The incorporation of the azo group in the obtained copolymers was determined from the results of elemental analysis (3.30–10.22% nitrogen) and Fourier transform infrared spectroscopy. Furthermore, the thermal properties of the obtained copolymers were examined using differential scanning calorimetry. X‐ray diffraction results showed that the synthesized copolymers were amorphous. © 2014 Society of Chemical Industry     

Radical Copolymerization of a Highly Fluorinated Cyclic Olefin Octafluorocyclopentene with Alkyl Vinyl Ethers

Summary Fluoropolymers are potential candidates for use in the fields of specific coating and lithography. Their versatility could be enhanced by increasing their glass transition temperature, T _g . In order to achieve this, the copolymerization of a highly fluorinated cyclic monomer, octafluoro-cyclopentene (OFCPE), with three kinds of alkyl vinyl ethers was investigated with a radical initiator in bulk. It was found that OFCPE and cyclohexyl vinyl ether (CHVE) copolymerized successfully, and the weight average molecular weight and T _g of the copolymer reached values of 12,000 and 124.9°C, respectively. Copolymer composition was close to a OFCPE:CHVE unit ratio = 0.5:0.5. The monomer reactivity ratios estimated by the Yamada-Itahashi-Otsu nonlinear least-squares procedure were found to be r _1,OFCPE = 0.005 ± 0.020 and r _2,CHVE = 0.154 ± 0.017.     

Synthesis of Poly(cyclohexyl vinyl ether-<Emphasis Type="Italic">b</Emphasis>-isobutylene-<Emphasis Type="Italic">b</Emphasis>-cyclohexyl vinyl ether) Triblock Copolymer by Living Cationic Sequential Copolymerization

Summary The living cationic polymerization of cyclohexyl vinyl ether (CHVE) and sequential block copolymerization of isobutylene with CHVE were carried out by the so-called capping-tuning technique in hexanes/CH₃Cl solvent mixtures at –80 °C. It involves capping the initiator, 2-chloro-2,4,4-trimethylpentane (TMPCl), or the living polyisobutylene (PIB) chain end with 1,1-ditolylethylene in the presence of titanium(IV) (TiCl₄), followed by fine-tuning of the Lewis acidity with the addition of titanium(IV) isopropoxide (Ti(OIp)₄) to match the reactivity of CHVE. Well-defined PCHVE, PIB-b-PCHVE and PCHVE-b-PIB-b-PCHVE with predesigned molecular weights and narrow molecular weight distributions (M_w/M_n<1.1) were thus prepared with [Ti(OIp)₄]/[TiCl₄] ratios of 1.6–1.8. Differential scanning calorimetry of the triblock copolymers showed two T_gs (–62 °C for PIB and 61 °C for PCHVE) suggesting a microphas-separated morphology of the triblock copolymers and the potential use of them as thermoplastic elastomers.     

Synthesis, characterization polymerization and antibacterial properties of novel thiophene substituted acrylamide

Ethyl 2-acrylamido-4,5,6,7-tetrahydrobenzo [b] thiophene-3-carboxylate (ETTCA) has been synthesized and its structure has been elucidated by elemental analysis and spectral tools. Free radical polymerization of (ETTCA) has been conducted in several solvents using azobisisobutyronitrile (AIBN) as an initiator. The kinetic parameters of polymerization of the ETTCA were investigated, and it was found that the polymerization reaction follows the conventional free radical scheme. The overall activation energy of polymerization ΔE was determined (ΔE = 45.11 kJ mol⁻¹). The copolymerization of ETTCA with three conventional monomers was carried out in dioxane at 65 °C. The monomer reactivity ratios for the copolymerization of ETTCA with methyl methacrylate (MMA), vinyl acetate (VA) and vinyl ether (VE) were calculated. Thermal stability of the ETTCA polymer and its copolymers were investigated by thermogravimetric analysis. It has been found that the prepared polymer (PETTCA) and its copolymers with VA have moderate biological activity and highly dependent on the copolymer composition.     

Absolute reactivity in the cationic polymerization of methyl and other alkyl vinyl ethers

The cationic polymerizations of methyl-, 2-chloroethyl-, ethyl-, cyclohexyl- and t-butyl- vinyl ethers initiated by cycloheptatrienyl hexachloroantimonate in methylene chloride solutions have been studied in detail. Reaction rates were measured by an adiabatic calorimetric technique and rate constants for propagation of each of the monomers, k_p (obs), were determined by appropriate kinetic analysis of the experimental curves. The results obtained are discussed in terms of current theories regarding ion pair/free ion equilibria in non-aqueous solvents. Although ethyl-, cyclohexyl- and t-butyl- vinyl ethers behave very similarly to isobutyl vinyl ether, and their reactivities are comparable [k_p (obs) ～ 3 × 10³M^?1sec^?1 at 0°C] both methyl- and 2-chloroethyl- vinyl ethers show markedly different characteristics to the others, and in particular exhibit a reactivity approximately one order of magnitude less [k_p (obs) ～ 2 × 10²M^?1sec^?1 at 0°C]. These variations in reactivity are discussed in terms of preferred monomer conformations, and the resulting differences in activation energy which are likely to arise when such conformers are approached by an electrophile.     

Synthesis,characterization, and antitumor activity of poly(maleic anhydride‐co‐vinyl acetate‐co‐acrylic acid)

The ternary copolymerization of maleic anhydride (MA), vinyl acetate (VA), and acrylic acid (AA) [P(MA‐co‐VA‐co‐AA)], which is considered to be an acceptor–donor–acceptor system, was carried out in 1,4‐dioxane with benzoyl peroxide as an initiator at 70°C under a nitrogen atmosphere. Constants of complex formation for the monomer systems in the study were determined by UV–visible (hydrogen‐bonding complex) and ¹H‐NMR (charge transfer complex) methods, respectively. The results show that polymerization of the P(MA‐co‐VA‐co‐AA) system proceeds by an alternating terpolymerization mechanism. It is shown that the synthesized copolymers have typical polyelectrolyte behavior, ability for reversible hydrolysis–anhydrization reactions, and semicrystalline structures. In these cases, including radical polymerization, and formation of semicrystalline structures, the hydrogen‐bonding effect plays a significant role. The in vitro cytotoxicities of the synthesized terpolymer and alternating copolymer were evaluated using Raji cells (human Burkitt lymphoma cell line). The antitumor activities of prepared anion‐active copolymers were studied using methyl–thiazol–tetrazolium colorimetric assay and 50% of the cytotoxic dose of each copolymer and terpolymer were calculated. Hydrolyzed P(MA‐co‐VA‐co‐AA) and P(MA‐alt‐AA) copolymers have sufficiently high antitumor activity, which depends on the amount of hydrogen‐bonding carboxylic groups and their regular distribution in the side chain of functional macromolecules. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3425–3432, 2006     

Kinetics of ylide-initiated radical copolymerization of 4-vinylpyridine and methyl methacrylate

The ylide-initiated radical copolymerization of 4-vinylpyridine (4-VP) with methyl methacrylate (MMA) at 60°C using carbon tetrachloride as inert solvent yields non-alternating copolymers. The kinetic parameters, average rate of polymerization (R_p) and orders of reaction with respect to monomers and initiator, have been evaluated and the kinetic equation is found to be R_pα[ylide]^0.94 [MMA]^1.0 [4-VP]^1.5. The values of the energy of activation and k_p²/k_t are 48 kJ mol^?1 and 6.6 × 10^?5 litre mol^?1s^?1, respectively. The copolymers have been characterized by IR and NMR spectroscopy.     

Copolymerizations of carbon dioxide and epoxides in the presence of rare earth coordinate catalyst

Carbon dioxide (CO₂) as a direct material was copolymerized with epoxides to synthesize new aliphatic polycarbonates, and the copolymerization was catalyzed by the coordinate catalyst composed of rare earth yttrium phosphonate and triisobutylaluminum [Y(P₂₀₄)₃–A1(i‐Bu)₃]. The epoxides used in this research included epichlorohydrin (ECH) and some new glycidol ether (GE) monomers prepared by the reaction of ECH and phenol or alcohol, such as α‐allyl glycidol ether, β‐chloroethyl glycidol ether, benzene glycidol ether, m‐tolyl glycidol ether, and benzyl glycidol ether. The copolymers were characterized by infrared (IR), ¹H nuclear magnetic resonance (‐NMR), and dynamic mechanical analysis. The results show that Y(P₂₀₄)₃–A1(i‐Bu)₃ had better catalytic activity in the copolymerization of CO₂ with epoxide, and the copolymerization rate of aryl GE was distinctly higher than that of aliphatic GE. Dynamic mechanical analysis indicated the glass transition temperature T_g of the copolymers GE–CO₂ were lower than that of ECH–CO₂. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2356–2359, 2003     

Synthesis,characterization, and gamma radiation effects over well‐defined poly(vinylsiloxanes) copolymers

Anionic ring‐opening polymerization (AROP) was employed for the controlled synthesis of linear model block copolymers of 1,3,5,7‐tetrametil‐1,3,5,7‐tetravinyl(cyclotetrasiloxane) (V₄) and 1,3,5‐dimethyl(cyclotrisiloxane) (D₃) monomers by using sec‐butyl lithium (sec‐Bu^?Li⁺) as initiator, and high‐vacuum anionic polymerization techniques. V₄ copolymerization was promoted by employing D₃ and sec‐Bu^?Li⁺ producing living silanolates that open the stable V₄ ring. For this purpose, two strategies were applied: (a) sequential addition of monomers, and (b) one‐step copolymerization at different reaction temperatures. According to the experimental results, higher levels of V₄ incorporation (～ 18.14 mol %) were obtained by mixing both co‐monomers and performing the reaction at high temperature (80°C). This strategy allowed the control of the V₄ incorporation into the copolymer structure, giving the opportunity of synthesizing model vinyl‐siloxane polymers. The gamma radiation of these materials showed that lower doses are needed to achieve the same gel content as in a model poly(dimethylsiloxane) (PDMS). In such a sense, these results constitute one of the first reports regarding the effect of gamma radiation on vinyl‐containing silicon polymers, and may be of fundamental importance if a biomedical cross‐linked rubber‐type PDMS is needed at earlier doses of sterilization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Design and synthesis of new photoresist materials for ArF lithography

A new class of photoresist matrix polymers based on vinyl ether–maleic anhydride (VEMA) alternating copolymers was developed for ArF single‐layer lithography. These polymers were synthesized by copolymerization of alkyl vinyl ether and maleic anhydride alternating copolymers with acrylate derivatives containing bulky alicyclic acid‐labile protecting groups. The resulting polymers showed good control of polymerization and high transmittance. Also, these resists exhibited good adhesion to the substrate, high dry‐etching resistance against CF₄ mixture gas (1.02 times the etching rate of deep UV resist), and high selectivity to silicon oxide etching. Using an ArF excimer laser exposure system with 0.6 NA, 120‐nm L/S patterns were resolved under conventional illumination. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 165–170, 2004     

Living copolymerization of octadecyl vinyl ether with isobutyl vinyl ether: copolymerization parameters and crystallization behaviour of the copolymers

Cationic copolymerization of octadecyl vinyl ether (ODVE) with isobutyl vinyl ether (IBVE) under reaction conditions leading to living vinyl ether polymerization has been studied. The experimental results show that, under such conditions, the living nature of the copolymerization can be retained. The copolymerization parameters were found to be r_IBVE = 2.2 and r_ODVE = 0.30. Incorporation of up to 50% of IBVE units has only a small effect on the crystallinity of ODVE units. This is ascribed to the fact that the crystallinity is due to the octadecyl side‐chains and not to the main chain, and that the copolymers have a gradient‐like (tapered) structure. © 2000 Society of Chemical Industry     

Alternating copolymers from the radical copolymerization of citraconic derivatives with isobutyl vinyl ether

Radical copolymerization of citraconic anhydride (CAn) with isobutyl vinyl ether (IBVE) was studied as well as the copolymerizations of N-alkylcitraconimides, dialkyl citraconates and mesaconates with IBVE. All the copolymerizations attempted except one, incorporating N-alkylcitraconimide, were found to give alternating copolymers with molecular weights of more than 10,000 in most cases. Of all the copolymerizations, the CAn-IBVE system showed the highest reactivity. A charge transfer complex between these two monomers was confirmed to exist in this system. The equilibrium constant of the complex formation was determined by UV spectroscopy as 0–162 litre/mol in CHCl₃ at 15°C. The alternating copolymer obtained from CAn with IBVE was converted to the corresponding copolymer of dialkyl citraconate by esterification.     

Synthesis and characterization of lignin–poly(acrylamide)–poly(2‐methacryloyloxyethyl) trimethyl ammonium chloride copolymer

In this work, two monomers, acrylamide (AM) and [2‐(methacryloyloxy)ethyl]trimethylammonium chloride (DMC) were copolymerized from kraft lignin (KL) in an aqueous suspension initiated by free radical copolymerization in the presence of potassium persulfate. The impact of copolymerization conditions on the charge density and molecular weight of the copolymers was investigated. The molecular weight and mass balance analyses confirmed that the homopolymer [polyDMC (PDMC) and polyAM (PAM)] and undesired copolymer (AM–DMC) productions dominated as time, initiator, and DMC dosage increased more than the optimum values. The activation energy of the polymerization of KL and AM (43.02 kJ mol^?1), KL and DMC (21.99 kJ mol^?1), AM (14.54 kJ mol^?1), DMC (10.34 kJ mol^?1), and AM and DMC (18.13 kJ mol^?1) was determined. Proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis confirmed the production of KL–AM–DMC copolymer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46338.     

Free radical copolymerization behavior of vinyl acetate with butyl acrylate in the presence of GeCl4 and BCl3

No alternating copolymers of vinyl acetate (VAc) and butyl acrylate (BA) were obtained by free radical copolymerization in the presence of GeCl₄ and BCl₃ (compared with the acrylic acid–vinyl acetate copolymerization system). By ultraviolet spectral analysis, it was concluded that both BCl₃ and GeCl₄ can form complexes with butyl acrylate. The BA–BCl₃ complex constants were determined by ¹H NMR; K_B=33·2 (25°C). The reason for the gel formation in the BA–Vac–BCl₃ copolymerization system was discussed. When vinyl acetate reacted with BCl₃, cationic polymerization probably occurred. A white gel product probably resulted from the polymerization of the BA–BCl₃ complex. © 1998 SCI.     

Formation of a soluble hyperbranched polymer via initiator–fragment incorporation radical copolymerization of divinyl adipate and isobutyl vinyl ether

The copolymerization of divinyl adipate (DVA) with isobutyl vinyl ether (IBVE) was conducted at 70 and 80 °C in benzene using azobisisobutyronitrile (AIBN), at a concentration as high as 0.50 mol l^?1 as the initiator, where the concentrations of DVA and IBVE were 0.40 and 0.60 mol l^?1, respectively. The copolymerization proceeded homogeneously, without any gelation, to yield soluble copolymers in spite of the high molar ratio of DVA as an excellent cross‐linker for IBVE. The copolymer yield increased with time, and the number‐average molecular weight (M_n = 0.9–2.4 × 10⁴ g mol^?1) from gel permeation chromatography (GPC) and molecular weight distribution (M_w/M_n = 1.5–7.6) of the resulting copolymer increased with copolymer yield. The cyanopropyl group, as a fragment of AIBN, was incorporated as a main constituent in the copolymer, the fraction of which increased from ca 10 to ca 20 % with copolymer yield, hence indicating that the copolymerization is an initiator–fragment incorporation radical polymerization. The copolymers also contained IBVE units (10–30 %) and DVA units with intact double bond (8–36 %) and without double bond (45 %). The intrinsic viscosity of the copolymer was very low (0.1 dl g^?1) at 30 °C in tetrahydrofuran. The results from GPC–multi‐angle laser light scattering (MALLS), transmission electron microscopy (TEM) and MALLS revealed that individual copolymer molecules were formed as hyperbranched nanoparticles. Copyright © 2004 Society of Chemical Industry     

The role of the ratio (PEG:PPG) of a triblock copolymer (PPG‐b‐PEG‐b‐PPG) in the cure kinetics,miscibility and thermal and mechanical properties in an epoxy matrix

The aim of this study was to evaluate the role of different poly(ethylene glycol):poly(propylene glycol) (PEG:PPG) molar ratios in a triblock copolymer in the cure kinetics, miscibility and thermal and mechanical properties in an epoxy matrix. The poly(propylene glycol)‐block‐poly(ethylene glycol)‐block‐poly(propylene glycol) (PPG‐b‐PEG‐b‐PPG) triblock copolymers used had two different molecular masses: 3300 and 2000 g mol^?1. The mass concentration of PEG in the copolymer structure played a key role in the miscibility and cure kinetics of the blend as well as in the thermal–mechanical properties. Phase separation was observed only for blends formed with the 3300 g mol^?1 triblock copolymer at 20 wt%. Concerning thermal properties, the miscibility of the copolymer in the epoxy matrix reduced the T_g value by 13 °C, although a 62% increase in fracture toughness (K_IC) was observed. After the addition of PPG‐b‐PEG‐b‐PPG with 3300 g mol^?1 there was a reduction in the modulus of elasticity by 8% compared to the neat matrix; no significant changes were observed in T_g values for the immiscible system. The use of PPG‐b‐PEG‐b‐PPG with 2000 g mol^?1 reduced the modulus of elasticity by approximately 47% and increased toughness (K_IC) up to 43%. Finally, for the curing kinetics of all materials, the incorporation of the triblock copolymer PPG‐b‐PEG‐b‐PPG delayed the cure reaction of the DGEBA/DDM (DGEBA, diglycidyl ether of bisphenol A; DDM, Q3‐4,4′‐Diaminodiphenylmethane) system when there is miscibility and accelerated the cure reaction when it is immiscible. All experimental curing reactions could be fitted to the Kamal autocatalytic model presenting an excellent agreement with experimental data. This model was able to capture some interesting features of the addition of triblock copolymers in an epoxy resin. © 2018 Society of Chemical Industry     

A study on thermal behavior of a poly(VDF‐CTFE) copolymers binder for high energy materials

This article describes a study on thermal behavior of poly(vinylidene fluoride‐chlorotrifluoroetheylene) [poly(VDF‐CTFE)] copolymers as polymeric binders of specific interest for high energy materials (HEMs) composites by thermal analytical techniques. The non‐isothermal thermogravimetry (TG) for poly (VDF‐CTFE) copolymers was recorded in air and N₂ atmospheres. The results of TG thermograms show that poly(VDF‐CTFE) copolymers get degrade at lower temperature when in air than in N₂ atmosphere. In the derivative curve, there was single maximum degradation peak (T_max) indicating one‐stage degradation of poly(VDF‐CTFE) copolymers for all the samples. The other thermal properties such as glass transition temperature (T_g) and degradation temperature (T_d) for poly(VDF‐CTFE) copolymers were measured by employing differential scanning calorimeter (DSC) technique. The kinetic parameters related to thermal degradation of poly(VDF‐CTFE) copolymers were investigated through non‐isothermal Kissinger kinetic method using DSC method. The activation energies for thermal degradation of poly(VDF‐CTFE) copolymers were found in a range of 218–278 kJ/mol. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and biological activity of medium range molecular weight polymers containing exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid

A new monomer, exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid (ETCA), was prepared by reaction of maleimidocaproic acid and furan. The homopolymer of ETCA and its copolymers with acrylic acid (AA) or with vinyl acetate (VAc) were obtained by photopolymerizations using 2,2‐dimethoxy‐2‐phenylacetophenone as an initiator at 25 °C. The synthesized ETCA and its polymers were identified by FTIR, ¹H NMR and ¹³C NMR spectroscopies. The apparent average molecular weights and polydispersity indices determined by gel permeation chromatography (GPC) were as follows: M_n = 9600 g mol^?1, M_w = 9800 g mol^?1, M_w/M_n = 1.1 for poly(ETCA); M_n = 14 300 g mol^?1, M_w = 16 200 g mol^?1, M_w/M_n = 1.2 for poly(ETCA‐co‐AA); M_n = 17 900 g mol^?1, M_w = 18 300 g mol^?1, M_w/M_n = 1.1 for poly(ETCA‐co‐VAc). The in vitro cytotoxicity of the synthesized compounds against mouse mammary carcinoma and human histiocytic lymphoma cancer cell lines decreased in the following order: 5‐fluorouracil (5‐FU) ≥ ETCA > polymers. The in vivo antitumour activity of the polymers against Balb/C mice bearing sarcoma 180 tumour cells was greater than that of 5‐FU at all doses tested. © 2001 Society of Chemical Industry     

Enhancement of mechanical and optical performance of commercial polystyrenes by blending with siloxane‐based copolymers

Well‐defined poly(styrene‐block ‐dimethylsiloxane) copolymers (PS‐b ‐PDMS) with low polydispersity index (M_w /M_n ) and different compositions were synthesized by sequential anionic polymerization of styrene (S) and hexamethyl(ciclotrisiloxane) (D₃) monomers. Synthesized PS‐b ‐PDMS copolymers were characterized by ¹H‐nuclear magnetic resonance, size exclusion chromatography, Fourier transform infrared spectroscopy, and transmission electron microscopy. The physicochemical characterization determined that block copolymers have molar mass values close to ～135,000 g mol^?1, narrow M_w /M_n < 1.3, and chemical composition ranging from low to intermediate PDMS content. Blends of these copolymers with a commercial polystyrene (PS) were obtained by melt mixing and subsequently injection. Films obtained were flexible, and showed lower transparency than the original PS matrix. On the other hand, a 10 wt % incorporation of PS‐b ‐PDMS copolymers leads to better mechanical performance by enhancing elongation at break (～8.8 times higher) and opacity values (～18 times higher). In addition, UV–Vis barrier capacity of the resulting blends is also increased (up to 400% higher). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45122.