Order in amorphous di‐n‐alkyl itaconate polymers,copolymers, and blends

The presence of a main‐chain correlation distance (d_II) in the poly(di‐n‐alkyl itaconate)s was confirmed with small‐angle X‐ray scattering/wide‐angle X‐ray scattering measurements taken over the temperature range of 293–478 K. Data for a series of alkyl acrylate polymers were also obtained for comparison. The intensity of the itaconate d_II peak was significant and indicated a greater level of nanophase formation than in analogous systems. In the lower members of the series, nanophase formation appeared to be further enhanced in the temperature range above the glass‐transition temperature (T_g). This was ascribed to the rapidly increasing main‐chain mobility in this region. Macroscopically phase‐separated itaconate blends displayed the individual d_II nanospacings of each homopolymer component. Copolymers, on the other hand, showed more interesting behavior. Poly(methyl‐co‐di‐n‐butyl itaconate) followed an average behavior in which the d_II spacing and T_g changed progressively with the comonomer content. In contrast, the side‐chain pairing in poly(methyl‐co‐di‐n‐octyl itaconate) generated d_II spacings characteristic of separate methyl and octyl nanodomains. The observation of the dioctyl nanodomains, along with the dioctyl side‐chain lower T_g relaxation event, confirmed the concept of independent side‐chain‐domain relaxation in these polymers. The temperature behavior of the poly(methyl‐co‐di‐n‐octyl itaconate) small‐angle X‐ray scattering profiles and scattering correlation lengths indicated that the two nanodomains were not completely structurally independent. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4000–4016, 2004     

Studies on grafting of tris(2‐methoxyethoxy)vinylsilane onto ethylene‐propylene‐diene terpolymer

New graft copolymer was prepared by incorporating tris(2‐methoxyethoxy)vinylsilane (TMEVS) on ethylene‐propylene‐diene terpolymer (EPDM) by using dicumyl peroxide (DCP) as initiator, in Haake Rheocord 90 torque rheometer. The effect of EPDM concentration, TMEVS concentration, reaction time, reaction temperature and initiator concentration on the graft co polymerization was studied. The grafting efficiency of TMEVS on EPDM was confirmed by Fourier Transform infrared (FT‐IR) spectroscopy. The grafting efficiency increased with increase in the silane concentration upto 6% by weight. The grafting efficiency decreased beyond 6% by weight due to homopolymerization of TMEVS and non‐availability of carbon–carbon double bond in the EPDM terpolymer. The thermal properties of peroxide cured EPDM and hot water cured EPDM‐g‐TMEVS were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. The results show thermal properties like degradation tempertature and glass transition temperature of the EPDM‐g‐TMEVS were increased due to introduction of TMEVS on to EPDM terpolymer as well as the formation of thermally stable three‐dimensional network. Copyright © 2004 John Wiley & Sons, Ltd.     

Preparation,characterization, and properties of fast‐responding bulk hydrogel and treated bleached banana pulp

The reaction between bleached banana pulp and pure maleic anhydride (MA) was investigated. The reaction was conducted in a reactor in the presence of xylene used as a solvent and sodium hypophosphite as catalyst. The appearance of infrared absorption bands at 1891 and 1708 cm^?1 indicated that MA chemically reacted by esterification with bleached banana pulp. However, evidence of an esterification reaction was obtained between cellulose and MA. The production of fast‐responding bulk hydrogel with a high swelling ratio was also investigated. This hydrogel was synthesized first by the formation of maleated acrylamide particles and then by the graft copolymerization of the particles with cellulose. The maleated acrylamide particles were characterized with mass spectroscopy, and the formed hydrogl was characterized by FT‐IR. The esterification reaction between bleached banana pulp and maleated acrylamide was also studied. Steam absorption for bulk hydrogel, maleated acrylamide‐treated bleached banana pulp, MA‐treated cellulose and bleached banana pulp is higher than the steam absorption for untreated cellulose and bleached banana pulp. Compared with treated bleached banana pulp and cellulose, the hydrogel had very high swelling ratios and much faster swelling rates attributed to the collaboration of the ionized particles and bulk hydrogel. The number of ionic maleated acrylamide groups in the hydrogel affected the swelling behavior. Copyright © 2004 John Wiley & Sons, Ltd.     

Konjac glucomannan‐graft‐acrylic acid hydrogels containing azo crosslinker for colon‐specific delivery

In this article, the synthesis and characterization of novel hydrogel systems designed for colon‐targeting drug delivery are reported. The gels were composed of konjac glucomannan, copolymerized with acrylic acid, and crosslinked by the aromatic azo agent bis(methacryloylamino)‐azobenzene. The influence of various parameters on the dynamic and equilibrium swelling ratios (SRs) of the hydrogels was investigated. It is shown that the SR was inversely proportional to the grafting degree of acrylic acid and the content of bis(methacryloylamino)‐azobenzene. The dependence of SR on the pH indicates that obtained hydrogels are potential for drug delivery to colon. It was possible to modulate the degree of swelling and the pH sensitivity of the gels by changing crosslinking density of the polymer. The main chain of hydrogels can be degraded by β‐glycosidase which is abundant in colon. They can be in vitro degraded for 73% in a month by Cereflo® and 86% in 20 days by Mannaway25L. We have also prepared the hydrogels that loaded with bovine serum albumin about 1.5%, 3%, 9%, and 20% by weight. In vitro release of model drug bovine serum albumin was studied in the presence of Mannaway25L or Fungamyl®800L in pH 7.4 phosphate buffer at 37 °C. The drug release can be controlled by the biodegradation of the hydrogels. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4370–4378, 2004     

Stabilization of water/n‐hexane emulsions by amphiphilic copolymers based on vinyl ethers and their polycomplexes with poly(acrylic acid)

Amphiphilic random copolymers based on vinyl ether of ethylene glycol and vinyl butyl ether as well as their polycomplexes with poly(acrylic acid) were studied as polymeric reagents for the stabilization of water/n‐hexane emulsions. The emulsion stability strongly depended on the content of vinyl butyl ether in the copolymers as well as their concentration in solution. The more hydrophobic copolymers stabilized emulsions more efficiently. An increase in the temperature and the addition of inorganic salts reduced the emulsion lifetime. The formation of interpolymer complexes between the copolymers and poly(acrylic acid) significantly influenced the stability of the emulsions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2625–2632, 2004     

Amphiphilic block copolymers of high‐molecular‐weight poly(ethylene oxide) and either ε‐caprolactone or γ‐methyl‐ε‐caprolactone: Synthesis and characterization

Ethylene oxide (EO) has been block‐polymerized with both ε‐caprolactone (ε‐CL) and γ‐methyl‐ε‐caprolactone (MCL) through the combination of the anionic polymerization of EO and the ring‐opening polymerization (ROP) of ε‐CL and MCL. ω‐Hydroxyl poly(ethylene oxide) has been reacted with triethylaluminum (OH/Al = 1) and converted into a macroinitiator for ROP of ε‐CL and MCL. In toluene at room temperature, this polymerization leads to a bimodal molecular weight distribution as a result of monomer insertion in only some of the aluminum alkoxide bonds. However, in a more polar solvent (methylene chloride) added with 1 equiv of a Lewis base (pyridine), the expected diblock is formed selectively, and this indicates that aggregation of the active species in toluene is responsible for a macroinitiator efficiency of less than 1. A series of amphiphilic diblock copolymers with poly(ε‐caprolactone) (semicrystalline) and poly(γ‐methyl‐ε‐caprolactone) (amorphous) as the hydrophobic blocks have been prepared and characterized with size exclusion chromatography, ¹H NMR, IR, and wide‐angle X‐ray scattering. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1132–1142, 2004     

基团转移聚合研究的最近进展

对基团转移聚合在引发剂、单体、催化剂、立体化学、嵌段和星型共聚物、终止反应、链转移反应以及应用方面的最近进展,进行了介绍和评述。     

Synthesis and characterization of novel poly(cycloalkyl methacrylate) bearing fused‐ring structure and its copolymers

A new family of cycloaliphatic fused‐ring acrylic polymers based on 8‐hydroxymethyltricyclo[5.2.1.0^2,6]decane (TCD) has been synthesized by free‐radical polymerization. TCD‐methacrylate (TCD‐MA) was synthesized by reacting TCD with methacrylic acid in toluene via transesterification with p‐toluenesulfonic acid as a catalyst. TCDMA was polymerized in toluene with benzoyl peroxide as a free‐radical initiator at 80 °C. Copolymers were synthesized by polymerizing TCDMA with styrene and methyl methacrylate. The composition of the comonomers was varied from 0 to 100%. Homo‐ and copolymers were characterized by Fourier transform infrared (FTIR) and ¹³C NMR spectroscopy. Molecular weight determination by gel permeation chromatography showed that the polymers were obtained in very high molecular weights in the range of M_n > 50,000 and M_w > 80,000 with relatively low polydispersity. The composition analysis of both the copolymer series were determined by ¹H NMR. The thermal properties of the homo‐ and copolymers were studied with differential scanning calorimetry and all the polymers were found to be amorphous. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5617–5626, 2004     

Synthesis of semifluorinated block copolymers by atom transfer radical polymerization

Two sets of styrene‐based semifluorinated block copolymers, one with a perfluoroether pendant group and another with a perfluoroalkyl group, were synthesized by atom transfer radical polymerization. Microphase separation of the block copolymers was established by small‐angle X‐ray scattering and differential scanning calorimetry (DSC). DSC measurements also showed that the perfluoroether‐based polymer had a low glass‐transition temperature (?44 °C). Contact‐angle measurements indicated that the semifluorinated block copolymers had low surface energies (ca. 13 mJ/m²). These materials hold promise as low‐surface‐energy additives or surfactants for supercritical CO₂ applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 853–861, 2004