Initiation system effects in the cationic copolymerization of tetrahydrofuran (THF)

Summary Macromonomeric peroxy initiator, poly tetrahydrofuran (poly-THF=inimer) were synthesized via cationic polymerization of THF by the mono- (t-BuBP) and tetra-bromo methyl benzoyl peroxides (BDBP)/ZnCl₂ initiating system. The macromonomers were characterized by ¹H-NMR, IR, and GPC techniques. Methyl methacrylate (MMA) polymerization initiated by poly-THF inimers at 80°C and different times in bulk gave crosslinked poly-THF-b-polymethyl methacrylate block copolymers. Swelling ratios of the crosslinked block copolymers obtained by taking in same amounts of poly-THF inimer and MMA monomer in CHCl₃ were decreased versus time. It was compared the results obtained from t-BuBP-, BDBP-ZnCl₂ initiating systems with t-BuBP-, BDBP-AgSbF₆ initiating systems for THF monomer. Poly(THF-b-MMA) crosslinked block copolymers containing undecomposed peroxide groups initiated the thermal polymerization of styrene, S, were used to obtain poly(THF-b-MM_A-b-S) crosslinked multicomponent copolymers at 90°C. The crosslinked multi component copolymers were investigated sol-gel analysis and swelling ratios in CHCl₃. "Active" poly(THF-b-MM_A) having peroxygen group were used in the free radical coupling reaction of poly butadien (Poly Bd). Poly(THF-b-MM_A)-polybutadien crosslinked blend soluble graft copolymers were obtained. Received: 31 July 2001/Revised version: 16 June 2002/ Accepted: 5 July 2002     

MMA-DMAEMA两亲嵌段共聚物的合成

在室温下，采用苄醇钾(BzOK)作引发剂通过氧阴离子聚合方法合成了相对分子质量、嵌段组成均可控且相对分子质量分布窄的两亲嵌段共聚物BzO—MMA—DMAEMA和BzO—MMA—DMAEMA。用^1HNMR、FTIR、GPC对共聚物进行表征。比较不同加料次序所获得的嵌段共聚物，发现相同“单体／引发剂”条件下，共聚物的组成完全一致，从而证明MMA和DMAEMA的氧阴离子聚合反应体系均为活性聚合。     

Synthesis and properties of well-defined poly (dimethylsiloxane)-b-poly(2-hydroxyethyl methacrylate) copolymers

Block copolymers containing dimethyl siloxane and 2-hydroxyethyl methacrylate sequences were synthesized by group transfer polymerization (GTP) of 2-trimethylsilyloxyethyl methacrylate (TMS-HEMA) using silyl ketene acetal terminated poly(dimethylsiloxane) (PDMS) as macroinitiator, followed by hydrolysis of TMS-HEMA to HEMA. The block copolymers were obtained with controlled molecular weight and narrow molecular weight distribution. Trimethylsilyl groups in the P(TMS-HEMA) block could be selectively hydrolyzed without cleaving Si-O bond in PDMS block. The block copolymers formed micelles in methanol, the effective diameters (R_h) of which were in the range of 78 – 110 nm with narrow distribution by dynamic light scattering (DLS). The TEM image showed micelles with a spherical shape. Received: 10 May 2001/Revised version: 23 August 2001/Accepted: 24 August 2001     

Preparation and identification of a soluble copolymer from pyrrole and o-toluidine

A series of copolymers were prepared by chemically oxidative polymerization of pyrrole (PY) and ortho-toluidine (OT) in HCl aqueous medium. The yield, intrinsic viscosity, and solubility of the copolymers were studied by changing the monomer molar ratio. The resulting PY/OT copolymers were identified by FTIR, ¹H–NMR, DSC, and WAXD techniques. The experimental results showed that the oxidative polymerization of pyrrole and o-toluidine is exothermic and the resulting polymers exhibit an enhanced solubility in most organic solvents compared with that of pyrrole homopolymer. The polymer obtained is a real and amorphous copolymer containing pyrrole and o-toluidine units. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 510–518, 2001     

Semifluorinated ABA triblock copolymers: Synthesis,characterization, and amphiphilic properties

In this study a series of novel semifluorinated ABA triblock copolymers with different fluorinated segment lengths and different fluorocarbon side‐chain structures were synthesized via atom transfer radical polymerization (ATRP) and macroinitiator techniques. The macroinitiator, telechelic bromine terminated polystyrene, was obtained from bulk ATRP of styrene with α,α′‐dibromo‐p‐xylene as the initiator and cuprous bromide/α,α′‐bispyridine complex as the catalyst. The polymerization reactions of 2‐[(perfluorononenyl)oxy] ethyl methacrylate and ethylene glycol monomethacrylate monoperfluorooctanoate were initiated by the macroinitiator in the presence of additional catalyst. The characterization of the block copolymers was performed by gel permeation chromatography, ¹H‐NMR spectroscopy, and differential scanning calorimetry. The surface activities of the block copolymers in toluene were investigated with the Wilhelmy plate method. The solid surface energy of the block copolymers was determined by measurement of the contact angles. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2625–2633, 2002     

Efficient synthesis of two or multi component block copolymers through living radical polymerization with polymeric photoiniferters

Summary To synthesize efficiently block copolymers, the radical polymerization of vinyl monomers with the polymers obtained by tetraethyl thiuram disulfide(TD) as polymeric photoiniferters has been investigated. These photopolymerizations were found to proceed via a living radical mechanism, i.e. both the whole polymer yields and the average molecular weight of the block copolymers increased with increasing of the polymerization time. By applying these living radical polymerizations, various block copolymers consisting of two, three and four component blocks were obtained in good yields, suggesting that these techniques are effective and useful for synthesizing multi component block copolymers through radical polymerizations of polar vinyl monomers.     

Multiblock copolymers synthesized in aqueous dispersions using multifunctional RAFT agents

Triblock copolymers were synthesized in aqueous dispersions in two polymerization steps using a low molar mass difunctional dithiocarbamate-based RAFT agent, and in merely one polymerization step using a macromolecular difunctional dithiocarbamate-based RAFT agent. Segmented block copolymers containing several alternating blocks of different polarities were synthesized in miniemulsion in merely two polymerization steps by applying multifunctional, dithiocarbamate-based RAFT agents. All polymerizations showed a linear increase of with monomer conversion. Evidence that this novel synthetic concept resulted in the formation of (multi)block copolymers was obtained by combining normal gel permeation chromatography with gradient polymer elution chromatography.     

Synthesis of polyisoprene-poly(methyl methacrylate) block copolymers by using polyisoprene as a macro-iniferter

Summary Polyisoprene (PI) was pre-polymerized by using benzyl diethyldithiocarbamate (BDC) as an iniferter. The obtained PI was subsequently used to react with methyl methacrylate (MMA) in order to investigate whether the relevant block copolymers can be achieved. Results from ¹H-NMR and GPC reveal that the PI-PMMA block copolymers were formed. This suggests that polymerization of isoprene through the use of BDC proceeded via a (psuedo) “living” mechanism. Received: 9 August 1999/Revised version: 27 September 1999/Accepted: 1 October 1999     

Synthesis of copolymers of a linoleic acid derivative and properties of the copolymer films

Addition copolymers of maleic anhydride and a commercially available conjugated fatty acid, Pamolyn 380, were synthesized via thermal initiation. The copolymers had moderately high molecular weights and were obtained in reasonable yields. The copolymers were characterized by nuclear magnetic resonance and infrared spectroscopy and by elemental analysis. Based on this analytical data and examples from the literature, the copolymers were assigned regularly alternating chain morphology. Coatings were formulated with the copolymers, and films over a metal substrate were evaluated. The films were found to have excellent solvent resistance, high hardness, and good gloss. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 261–267, 2001     

Synthesis of novel amphiphilic graft copolymers composed of poly(ethylene oxide) as backbone and polylactide as side chains

A well-defined amphiphilic comb-like copolymer of poly(ethylene oxide)(PEO) as main chain and polylactide (PLA) as side chain was successfully prepared via a combination of anionic polymerization and coordination-insertion ring-opening polymerization. The anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE) was carried out using potassium 2-(2-methoxyethoxy)ethoxide as initiator, and then ethoxyethyl groups of EEGE units of the copolymers obtained were removed by hydrolysis. Two copolymers of methoxypoly(ethylene oxide-co-glycidol) [mpoly(EO-co-Gly)] were formed with multiple hydroxyl sites (the molar ratio values of Gly to EO in copolymers: 1/10.6 and 1/5.2; Mn: 10,100 and 5,020 respectively), and them were used further to initiate the ring-opening polymerization of lactide in the presence of stannous octoate, and a well-defined comb-like copolymer of PEO as main chain and PLA as side chain was obtained. The intermediate and final products of PEO-g-PLA were characterized by GPC and NMR in detail.     

A novel approach for synthesis of poly(norbornene)‐co‐poly(styrene) block copolymers via metathesis polymerization and free‐radical polymerization

It is successfully realized that block copolymers are synthesized via metathesis polymerization followed by free‐radical polymerization. This method is performed using styrene (St) and norbornene, one block is synthesized using the Grubbs second generation catalyst in the presence of chain transfer agents, and the subsequent polymerization of St is initiated by azo compounds to complete the additional blocks in the copolymers. The use of free‐radical polymerization instead of controlled radical polymerization or ionic polymerization can be potentially superior for industrialization. As a result, the molecular weights of the block copolymers ranging from 10.4 to 54.3 kDa and polydispersity indices ranging from 1.30 to 1.91 are obtained. In principle, this new method can be potentially useful to prepare a broad range of block copolymers with cyclic olefin groups in the main chains, which may be used in some particular applications.     

Synthesis and characterization of novel block copolymer from trans‐4‐hydroxy‐L‐proline and poly(ethylene glycol)

A series of novel ABA‐type block copolymers were synthesized by polymerization of trans‐4‐hydroxy‐L ‐proline (HyP) in the presence of various molecular weight poly(ethylene glycol)s (PEGs), a bifunctional OH‐terminated PEG using stannous octoate as catalyst. The optimal reaction conditions for the synthesis of the copolymers were obtained with 5 wt % stannous octoate at 140°C under vacuum (20 mmHg) for 24 h. The synthesized copolymers were characterized by IR spectroohotometry, proton nuclear magnetic resonance, differential scanning calorimetry, and Ubbelohde viscometer. The glass transition temperature (T_g) of the copolymers shifted to significantly higher temperature with increasing the number average degree of polymerization and HyP/PEO molar ratio. In contrast, the melting temperature (T_m) decreased with increasing the HyP/PEO molar ratio. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1581–1587, 2001     

Preparation of amphiphilic PS-b-PMAA diblock copolymer by means of atom transfer radical polymerization

Amphiphilic diblock copolymers of polystyrene-b-poly(methacrylic acid) were synthesized by means of atom transfer radical polymerization. First, the polystyrene with a bromine atom at the chain end (PS-Br) was prepared using styrene as the monomer, 1-bromoethyl benzene as the initiator, and CuCl/2,2′-bipyridyl (bpy) as the catalyst ([1-bromoethyl benzene]/[CuCl]/[bpy] = 1:1:3). The polymerization was well controlled. Second, the diblock copolymer of polystyrene-b-poly(tert-butyl methacrylate) was synthesized also by atom transfer radical polymerization using PS-Br as the macro-initiator, CuCl/bpy as the catalyst, and tert-butyl methacrylate (tBMA) as the monomer. Finally, the amphiphilic diblock copolymer, PS-b-PMAA, was obtained by hydrolysis of PS-b-PtBMA under the acid condition. The molecular weight and the structure of aforementioned copolymers were characterized with gel permeation chromatography, infrared, and nuclear magnetic resonance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2381–2386, 2001     

Effect of polymerization conditions on o‐phenylenediamine and o‐phenetidine oxidative copolymers

A series of new o‐phenylenediamine (OPD)/o‐phenetidine (PHT) copolymers with partly phenazine‐like structures has been successfully synthesized at three polymerization temperatures by chemically oxidative polymerization in four different polymerization media. The molecular structures and properties of the resulting OPD/PHT polymers were investigated by IR, UV–vis and high‐resolution ¹H NMR spectroscopies, and DSC, in order to ascertain the effect of reaction temperature, comonomer ratio and acid medium. The copolymerization mechanism of OPD with PHT monomers has been proposed. It is found that the statistical OPD/PHT copolymer obtained at a temperature of 118 °C has a higher degree of polymerization than that obtained at 12–17 °C. The OPD content in the copolymers calculated from NMR spectroscopic analysis is higher than that in the feed OPD content, whereas the OPD content calculated from element analysis is slightly lower than the feed OPD content. It can be predicted that denitrogenation takes place in the OPD units during the polymerization process at OPD/PHT molar ratios of 90/10 and 100/0. These OPD/PHT copolymers exhibit a much better solubility than the OPD homopolymer, hence suggesting an incorporation of PHT units into the phenazine structure of the homopolymer. The thermal behavior of the copolymers was also studied. Copyright © 2004 Society of Chemical Industry     

Polymeric N‐allyl vinylpyridinium salts as addition–fragmentation type initiators for cationic polymerization

Polymeric allyl pyridinium salts were synthesized from styrene and 4‐vinyl pyridine copolymers by quaternization and counteranion exchange reactions. The initiation capability of these copolymers, in conjunction with a photochemical free radical source such as benzoin, via an addition –fragmentation mechanism in the cationic polymerization of cyclohexene oxide is investigated. © 2001 Society of Chemical Industry     

Synthesis of new imidazole-based monomer and copolymerization studies with methyl methacrylate

In this study, copolymers were synthesized using methyl methacrylate (MMA) and 2-allyloxymethyl-1-methylimidazole (AOMMI) monomers at various ratios. For this purpose, hydroxyl end-functionalized imidazole was initially prepared with 1-methylimidazole and then it was used to prepare allyl-derived imidazole monomers. Finally, the synthesis of copolymers (poly(MMA-co-AOMMI)) was carried out using different proportions of commercial MMA and AOMMI monomers. Photopolymerization method was preferred as polymerization technique. The polymerization was carried out in solvent-free medium and benzophenone was used as the initiator. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR) and elemental analysis were used for the structural characterization of the obtained copolymers. Molecular weights and the thermal behaviour of the synthesized copolymers were analysed with gel permeation chromatography (GPC) and thermogravimetry (TG) techniques, respectively. The surface of the products was tried to be illuminated using scanning electron microscopy (SEM). According to the obtained FTIR, NMR and elemental analysis results, the copolymers were successfully synthesized. A number average molecular weights of poly(MMA-co-AOMMI) samples were found 13,500 (MMA:2/AOMMI:1), 16,600 (MMA:1/AOMMI:2) and 17,300 (MMA:1/AOMMI:1) according to the mixing ratios. When the thermal stabilities of the synthesized copolymers were observed, it has been seen that those containing imidazole had higher stability than the neat PMMA.     

A linkage moment approach to modeling condensation polymerization with multiple monomers. I. Linear polymers

In recent years, industrial interest in condensation copolymers with controlled microstructures has been increasing as these systems add an additional dimension to the design and manipulation of product properties without requiring completely new routes for monomer or polymer synthesis. The techniques used to control the compositional microstructure in condensation systems differ greatly from those in vinyl polymerization, as condensation polymers are continuously broken apart and reformed during the course of the polymerization. Blocky copolymers may be produced in a melt blending process only by limiting the contact time at reaction temperatures because the ultimate result of the polymerization and interchange reactions is complete randomization of the copolymer with a structure similar to that obtained in vinyl polymerization with all reactivity ratios equal to one. The design of processes yielding the desired product microstructure therefore requires a quantitative understanding of the effect of each reaction on the copolymer composition. As typical copolymer recipes include multiple monomers with different functionalities, in this paper a general copolycondensation model is presented that can accommodate an arbitrary number of monomers of differing reactivities. In this paper, only monofunctional and bifunctional monomers are considered; the extension to the case of gelating systems is left for a future paper. The use of this framework and the validity of the approach is demonstrated for an example situation in which a polyarylate is melt blended with PBT to produce a copolymer whose average sequence length may be controlled by limiting the extent of reaction. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 246–265, 2001     

Synthesis of thermosensitive polymers containing sugar branches

Copolymers of 6‐O‐vinyladipoyl‐D ‐glucose (VAG) and N‐isopropyl acrylamide (NIPAm) were synthesized by radical polymerization. The number‐average molecular weights of the copolymers were 3 × 10⁴ ≈ 6 × 10⁴. The observed segment composition of copolymers at the feed molar ratio (VAG 25/NIPAm 75) was VAG 10/NIPAm 90. The polymerization rate of the VAG monomer was slower than that of the NIPAm monomer. The lower critical‐solution temperature of copolymers measured with a light‐scattering photometer and a differential scanning calorimeter increased with increasing VAG segment composition. The increase in transition temperature was accompanied by a decrease in transition heat. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 384–387, 2001     

A soluble ladder copolymer from m-phenylenediamine and ethoxyaniline

A series of partial ladder copolymers were synthesized by chemically oxidative polymerization of m-phenylenediamine (MPD) and o-ethoxyaniline (EOA) using inorganic oxidants in inorganic acidic aqueous media. The polymerization yield, intrinsic viscosity, solubility, and thermal property of the copolymers were systematically studied by changing the comonomer ratio, initial polymerization temperature, polymerization time, oxidant, monomer/oxidant ratio, and acidic medium. As-prepared fine powder of the MPD/EOA copolymers was characterized by IR, UV-vis, and high-resolution ¹H NMR spectroscopies and DSC. Circular dichroism technique was firstly used to characterize chain structure of the copolymers. The results showed that the oxidative polymerization from MPD and EOA is exothermic and the resulting copolymers exhibit a remarkably enhanced solubility in all of the organic and inorganic solvents chosen as compared with totally insoluble MPD homopolymer. The polymers obtained by the oxidative polymerization are real copolymers containing MPD and EOA units but do not contain MPD and EOA homopolymers based on a careful solubility comparison. The actual MPD/EOA molar ratio calculated based on ¹H NMR spectra of the polymers is different from element analysis results. Element analysis indicated that denitrogenation happens during the polymerization linkage among MPD units and the structure consisting of MPD units is different from that reported. The ladder degree of the copolymers might be monitored by controlling MPD/EOA ratio. The DSC measurement indicates that the copolymers do not exhibit melt transition.     

New syntheses of graft copolymers using the DPE-technique: ATRP graft copolymerization

Summary A new one-step synthesis of a set of macroinitiators for atom transfer radical polymerization (ATRP) via controlled radical polymerization is presented. The macroinitiators consist of methacrylate and p-chloromethylstyrene (CMS) and were synthesized by controlled radical polymerization in the presence of l,l-diphenylethylene (DPE) using azobisisobutyronitrile (AIBN) as initiator. The resulting macroinitiators were used for the ATRP of different methacrylates yielding graft copolymers which were characterized by SEC and NMR. Received: 25 July 2002/Revised version: 28 October 2002/ Accepted: 28 October 2002 Correspondence to Oskar Nuyken