Synthesis of poly(arylene ether nitrile ketone)s bearing phthalazinone moiety and their properties

Copoly(arylene ether nitrile ketone)s bearing phthalazinone moiety (PPENKs) were successfully synthesized by the nucleophilic substitution reaction of 4-(4-hydroxylphenyl)-2,3-phthalazin-1(2H)-one (DHPZ), a new bisphenol-like monomer with twisted non-coplanar structure, with various molar proportions of 2,6-dichlorobenzonitrile (DCBN) to 4,4′-difluoro benzophenone (DFK) as coreactants in sulfolane at the present of anhydrous potassium carbonate. In order to obtain high-molecular weight polymers, DHPZ firstly polymerized with low-reactive DCBN for a given time at polymerization temperature after removal of water produced during the reaction, followed by addition of high-reactive DFK to continue the reaction until high-molecular weight polymers were obtained. These obtained copolymers had inherent viscosities between 0.45 and 0.80 dL/g in chloroform at a concentration of 0.5 g dL^?1 at 25 °C, and their number-average molecular weights were in the ranges from 2.2 × 10⁴ to 4.7 × 10⁴ with the polydispersity of 2.05–2.70. The structure of typical PPENK5050 was ambiguously confirmed by FT-IR and ¹H-NMR. All of the PPENKs were amorphous and soluble in dipolar aprotic solvents, involving N-methyl pyrrolidione, N,N-dimethylacetamide, and chloroform at room temperature. The resulting copolymers showed glass transition temperatures (T _gs) between 267 and 287 °C, and the T _g values of the copolymers were found to increase with increasing DCBN unit content in the polymer. Thermogravimetric studies showed that all of the polymers had 5 % weight loss temperatures ranging from 501 to 511 °C in nitrogen atmosphere. All of the PPENKs could be cast into transparent, strong, and flexible films. They displayed electrical surface resistivity of 10¹³ Ω, indicating their potential application in electronic field. Physical properties of PPENK5050, which exhibited the best mechanical properties, were measured according to ASTM plastic standards. The results indicated that PPENK5050 possessed excellent thermal properties with the heat deformation temperature of 270 °C, which was 100 °C higher than PEN? invented and commercialized by Idemitsu Kosan Company Limited. Its dielectric coefficient was 3.45 with the dielectric loss of 0.004 detected at 1 MHz. The other properties of PPENK5050 were equivalent to PEN?. They could be the promising materials as high-performance matrix in the application of polymer matrix composite, high-performance coating, adhesive, and membrane.     

Novel amphiphilic temperature responsive graft copolymers PCL-<Emphasis Type="Italic">g</Emphasis>-P(MEO<Subscript>2</Subscript>MA-<Emphasis Type="Italic">co</Emphasis>-OEGMA) via a combination of ROP and ATRP: synthesis,characterization, and sol-gel transition

A series of well-defined novel amphiphilic temperature-responsive graft copolymers containing PCL analogues P(αClεCL-co-εCL) as the hydrophobic backbone, and the hydrophilic side-chain PEG analogues P(MEO₂MA-co-OEGMA), designated as P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) have been prepared via a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The composition and structure of these copolymers were characterized by ¹H NMR and GPC analyses. The self-assembly behaviors of these amphiphilic graft copolymers were investigated by UV transmittance, a fluorescence probe method, dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. The results showed that the graft copolymers exhibited the good solubility in water, and was given the low critical temperature (LCST) at 35(±1) °C, which closed to human physiological temperature. The critical micelle concentrations (CMC) of P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) in aqueous solution were investigated to be 2.0 × 10^?3, 9.1 × 10^?4 and 1.5 × 10^?3 mg·mL^?1, respectively. The copolymer could self-assemble into sphere-like aggregates in aqueous solution with diverse sizes when changing the environmental temperature. The vial inversion test demonstrated that the graft copolymers could trigger the sol-gel transition which also depended on the temperature.     

Synthesis and characterization of polyimides from 4,4′-(3-(<Emphasis Type="Italic">tert</Emphasis>-butyl)-4-aminophenoxy)diphenyl ether

A novel diamine 4,4′-(3-(tert-butyl)-4-aminophenoxy)diphenyl ether (4) was synthesized from 2-tert-butylaniline and 4,4′-oxydiphenol through iodination, acetyl protection, coupling reaction and deacetylation protection. Then some polyimides (PIs) were obtained by one-pot polycondensation of diamne 4 with several commercial aromatic dianhydrides respectively. They all exhibit enhanced solubility in organic solvents (such as NMP, DMF, THF and CHCl₃ etc.) at room temperature. Their number-average molecular weights are in the range of (2.1–3.7)?×?10⁴ g/mol with PDI from 2.25 to 2.74 by GPC. They can form transparent, tough and flexible films by solution-casting. The light transparency of them is higher than 90% in the visible light range from 400 nm to 760 nm and the cut-off wavelengths of UV–vis absorption are below 370 nm. They also display the outstanding thermal stability with the 5% weight loss temperature from 525 °C to 529 °C in nitrogen atmosphere. The glass transition temperatures (T _g s) are higher than 264 °C by DSC. XRD results demonstrate that these PIs are amorphous polymers with the lower water absorption (<0.66%). In summary, the incorporation of tert-butyl groups and multiple phenoxy units into the rigid PI backbones can endow them excellent solubility and transparency with relatively high T _g s.     

Dehydration of fructose into 5-hydroxymethylfurfural in the presence of ionic liquids

The acid-catalyzed dehydration of fructose was performed in a microbatch reactor at 80 °C using two commercially available ionic liquids, a hydrophilic one, 1-butyl 3-methyl imidazolium tetrafluoroborate (BMIM⁺BF₄⁻), and a hydrophobic one, 1-butyl 3-methyl imidazolium hexafluorophosphate (BMIM⁺PF₆⁻). When the reaction is carried out in 1-butyl 3-methyl imidazolium tetrafluoroborate as solvent and Amberlyst-15 as catalyst, a yield up to 50% in 5-hydroxymethylfurfural (HMF) is obtained within around 3 h. When the reaction is carried out now in 1-butyl 3-methyl imidazolium tetrafluoroborate and in 1-butyl 3-methyl imidazolium hexafluorophosphate as solvents and Amberlyst-15 as catalyst, DMSO is used as a co-solvent, in order, in particular, to solubilize fructose in the hydrophobic ionic liquid. Under these conditions, both ionic liquids allow the reaction to work more rapidly than in DMSO alone and with yields in HMF close to 80% within 24 h.     

Investigation of novel polytriazole resins

2,4,6-Tri(4-propargyloxy-phenyl)pyridine(POPP) was made from 2,4,6-tri (4-hydroxyphenyl)pyridine(HPP) and propargyl bromide. The chemical structures of POPP and HPP were well characterized by means of FTIR, ¹H-NMR, ¹³C-NMR, and elemental analysis. Novel polytriazole resins (P-PTA resins) were prepared from POPP and azide compounds via 1, 3-dipolar cycloaddition reaction and characterized by solubility, FTIR, DSC, and TGA analyses. The P-PTA resins show good solubility in common solvents. The resins could be cured at 80 °C. The glass transition temperature (T_g) and the 5% weight loss temperature (T_d5) of the cured P-PTA-33 resin arrive at 310 and 365 °C in nitrogen atmosphere, respectively.     

Soluble and thermally stable copoly(phenyl-s-triazine)s containing both diphenylfluorene and phthalazinone units in the backbone

A series of novel copoly(phenyl-s-triazine)s were prepared by solution polycondensation of 2,4-bis(4-fluorophenyl)-6-phenyl-1,3,5-s-triazine (BFPT) with 9,9-bis(4-hydroxyphenyl)fluorine (BHF) and 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one (HHPZ) to investigate the effects of bulky diphenylfluorene units on solubility as well as thermal and mechanical properties. The synthetic procedure was efficiently optimized, resulting in high M _n up to 4.3 × 10⁴ g/mol in GPC. Moreover, the introduction of diphenylfluorene moieties in the main chains leads to the outstanding modification in the solubility of the copolymers in common organic solvents, such as chloroform, chlorobenzene (CB) and N-methylpyrrolidone (NMP). Simultaneously, the copolymers exhibit remarkable dimensional stability as evidenced by DMA, and maintain excellent thermal properties with glass transition temperatures (T _gs) ranging from 307 to 340 °C, 5 % mass-loss temperatures lying between 525 and 551 °C, and char yields at 800 °C higher than 55 % in N₂. Their solubility increases with the increase of diphenylfluorene content in the polymer backbone, and the thermal properties just decrease slightly. The films obtained via solution casting technology possess commendable mechanical properties, even at elevated temperatures.     

Synthesis of PAA-g-PNIPAM well-defined graft polymer by sequential RAFT and SET-LRP and its application in preparing size-controlled super-paramagnetic Fe3O4 nanoparticles as a stabilizer

A series of well-defined double hydrophilic graft copolymers, poly(acrylic acid)-g-poly(N-isopropylacrylamide) (PAA-g-PNIPAM), was employed as a novel water-soluble coating for constructing superparamagnetic iron oxide nanoparticles. The copolymer was synthesized via a three-step procedure: firstly, a well-defined hydrophobic PtBA-based backbone, poly(tert-butyl 2-((2-chloropropanoyloxy)-methyl)acrylate)-co-poly(tert-butyl acrylate), (PtBCPMA₁₉-co-PtBA₁₈), was prepared through RAFT copolymerization of a new trifunctional acrylic monomer, tert-butyl 2-((2-chloropropanoyloxy)methyl)acrylate and tert-butyl acrylate; secondly, taking this backbone as a macroinitiator to initiate SET-LRP of N-isopropylacrylamide resulted in well-defined (poly(tert-butyl 2-((2-chloropropanoyloxy)methyl)-acrylate)-co-poly(tert-butyl acrylate))-g-poly(N-isopropylacrylamide) ((PtBCPMA-co-PtBA)-g-PNIPAM) amphiphilic graft copolymers with relatively narrow polydispersities (M_w/M_n ≤ 1.31); thirdly, handling (PtBCPMA-co-PtBA)-g-PNIPAM in acidic conditions afforded PAA-g-PNIPAM graft copolymers. The resulting PAA-g-PNIPAM copolymers were directly utilized as a polymeric stabilizer in the preparation of superparamagnetic Fe₃O₄ nanoparticles. The particle size can be readily tuned in the range of 12.1–23.2 nm by varying the amount of PAA-g-PNIPAM copolymer or the length of PNIPAM side chain. Besides, the structure and properties of prepared Fe₃O₄/polymer nanocomposites were characterized by XRD, FT-IR, TGA, TEM, and magnetic measurement in detail.     

Polyhydrosilane Mediated Synthesis of One-Dimensional Gold Nanostructures

This work presents a solution-phase approach for the “one pot” synthesis of polysilane-gold nanorods. The process starts by the reduction of HAuCl₄ to Au^o with a solution of poly[diphenylsilane-co-methyl(H)silane] cooled to 4 °C. The formed small Au nanoparticles (5–15 nm diameter) serve further as seeds for the heterogeneous nucleation and anisotropic growth that takes place at 25 °C and yields crystalline needle-like polymer–gold nanostructures. The evolution of the small spherical nanoparticles to nanorods with length/width aspect ratios up to 10³ has been proved by UV–Vis spectroscopy, polarized light microscopy and AFM. Further insights on the growth mechanism were obtained by SEM, DLS and TEM.     

Synthesis,thermal degradation and dielectric properties of poly[2-hydroxy,3-(1-naphthyloxy)propyl methacrylate]

2-Hydroxy-3-(1-naphthyloxy)propyl methacrylate (NOPMA) monomer was synthesized from reaction of 2-[(2-naphthyloxy)methyl]oxirane with methacrylic acid in the presence of pyridine. The polymerization of NOPMA was carried out by free radical polymerization method in the presence of AIBN at 60 °C. The structure of monomer and polymer was characterized by ¹H-NMR, ¹³C-NMR and FT-IR spectroscopy techniques. The glass transition temperature and average-molecular weights of poly(NOPMA) were measured using differential scanning calorimetry and gel permeation chromatography, respectively. The thermal degradation behavior of poly(NOPMA) has been investigated by FT-IR studies of the partially degraded polymer and thermogravimetry. The cold ring fractions (CRFs) were collected at two different temperatures, initially fraction-1 (CRF₁) is from room temperature to 320 °C, and the other fraction-2 (CRF₂) is from 320 to 500 °C. The volatile products of the degradation were trapped at ?195 °C (in liquid nitrogen). All the fractions were characterized by FT-IR, ¹H and ¹³C-NMR spectroscopic techniques, and the cold ring fractions (CRFs) were also characterized by GC–MS. For the degradation of polymer, the major compound between products of CRFs is α-naphthol. The GC–MS, FT-IR and NMR data showed that depolymerization corresponding to monomer was not prominent below 320 °C in the thermal degradation of poly(NOPMA). The mode of thermal degradation containing formation of the major products was identified. The dielectric permittivity (ε′), the loss factor (ε″) and conductivity (σ_ac) were measured using a dielectric analyzer in the frequency range of 50 Hz to 20 kHz.     

Improved Curie temperature,electromechanical properties and thermal stability in ZnO-modified 0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 ceramics with coexisting monoclinic and tetragonal phases

Further improving electromechanical properties and overcoming relatively low Curie temperature (T_c) of (1-x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ (PMN-100xPT) are still two scientific issues. Here, we demonstrate a stable coexistence of monoclinic-tetragonal (M_C-T) phases in ZnO-modified PMN-32PT (PMN-32PT:xZnO) due to the diffusion-induced substitution of Zn²⁺ for Mg²⁺. The Curie temperature, saturated polarization, remnant polarization, piezoelectric coefficient (T_c, P_s, P_r, d₃₃) are increased from (160 °C, 22.0 μC/cm², 13.3 μC/cm², 350 pC/N) for x = 0 to (180 °C, 30.3 μC/cm², 22.4 μC/cm², 470 pC/N) for x = 0.06. Moreover, the thermal stability is improved. After annealing at 150 °C, the x = 0.06 sample shows retrained d₃₃ value of 209 pC/N, about 4 times larger than that of x = 0 counterpart. The improved properties are attributed to the substituting increased polar nanoregions and easy domain switching in M_C phase.     

Preparation of l-Lactide/3-Glycidyloxypropyltrimethoxysilane Copolymeric Materials with Various Catalysts

Copolymerization reactions of 3-glycidyloxypropyltrimethoxysilane (GPTS) with l-lactide (LLA) at 100 °C for different time intervals are performed by various catalysts such as zirconium perfluoroheptanoate, and commercially available Tin(II) chloride (SnCl₂) and sodium trimethylsilanolate (NaOSiMe₃). Homo- and copolymers are characterized by FTIR, ¹H- and ¹³C-NMR spectroscopies, electrospray ionization mass spectroscopy, thermal gravimetric analysis, differential scanning calorimetry and gel permeation chromatography. All selected catalysts are effective in ROP of monomers. Especially, SnCl₂ is more reactive catalyst in the copolymerization of LLA/GPTS. The structure of final product is found as random copolymers.     

The Chichibabin Amination of 5-Phenylpyrimidine and Phenylpyrazine [1,2]

5-Phenylpyrimidine ( 1 ) on treatment by KNH₂/NH₃, affords a mixture of 2 amino- and 4-amino-5-phenylpyrimidine. The presence of only the anionic C-4 adduct. 4-amino-5-phenyl-1 (or 3), 4-dihydropyrimidinide was shown by ¹H- and ¹³C-NMR spectroscopy of a solution of 1 in KNH₂/NH₃. Study of the amination by use of ¹⁵N-labelled KNH₂/NH₃ convincingly shows that in the formation of the 2-amino compound a ring opening-ring closure sequence is involved. The amination of phenylpyrazine ( 11 ) into 5-amino- and 3-amino-2-phenylpyrazine has been found to occur without opening of the pyrazine ring. Examination by ¹H- and ¹³C-NMR spectroscopy of a solution of 11 in KNH₂/NH₃, reveals that at −60°C three adducts are present; i.e. 3-amino-, 5-amino- and 6-amino-2-phenyl-dihydropyrazinides, at −40°C the C-3 and C-5 adducts are formed; and at room temperature only the thermodynamically most stable C-5 adduct is present.     

Chitosan-<Emphasis Type="Italic">g</Emphasis>-poly(4-acrylamidobenzenesulfonamide) copolymers: synthesis,characterization, and bioactivity

The monomer, 4-acrylamidobenzenesulfonamide (ABS), was synthesized via reaction of acryloyl chloride with 4-aminobenzenesulfonamide in acetone at 0 °C. This monomer was then grafted onto chitosan using solution containing 2% acetic acid and mixture of K₂S₂O₈ and Na₂SO₃ as the redox promoter. An optimal G% of 150% was obtained when the process is conducted at 60 °C for 3 h employing 3.0 × 10^?3 M K₂S₂O₈ and 1.5 × 10^?3 M Na₂SO₃. The graft copolymers, chitosan-g-poly(4-acrylamidobenzenesulfonamide), were characterized by using FTIR, XRD, and SEM. The results were shown that the crystallinity of chitosan is enhanced by increasing the monomer content through the grafting process. Potential Antimicrobial activities of the permethyl ammonium salt forms of chitosan and its grafted copolymers against selected microorganisms were evaluated. The results show that the graft copolymers display better inhibitory effects on the growth of bacteria and some fungi than does chitosan.     

Preparation of high surface area mesoporous nickel oxides and catalytic oxidation of toluene and formaldehyde

Mesoporous nickel oxide (NiO) nanoparticles were synthesized by the thermal decomposition reaction of Ni(NO₃)₂·9H₂O using oxalic acid dihydrate as the mesoporous template reagent. The pore structure of nanocrystals could be controlled by the precursor to oxalic acid dihydrate molar ratio, thermal decomposition temperature and thermal decomposition time. The structural characteristic and textural properties of resultant nickel oxide nanocrytals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N₂ adsorption–desorption isotherm and temperature programmed reduction. The results showed that the most excellently mesoporous nickel oxide particles (m-Ni-1-4) with developed wormlike pores were prepared under the conditions of the mixed equimolar precursor and oxalic acid and calcined for 4 h at 400 °C. The specific surface area and pore volume of m-Ni-1-4 are 236 m² g^?1 and 0.42 cm³ g^?1, respectively. Over m-Ni-1-4 at space velocity = 20,000 mL g^?1 h^?1, the conversions of toluene and formaldehyde achieved 90 % at 242 and 160 °C, respectively. It is concluded that the reactant thermal decomposition with oxalic acid assist is a key step to improve the mesoporous quality of the nickel oxide materials, the developed mesoporous architecture, high surface area, low temperature reducibility and coexistence of multiple oxidation state nickel species for the excellent catalytic performance of m-Ni-1-4.     

Novel copolymers of trisubstituted ethylenes with styrene — 7. Methyl 2-cyano-3-dihalophenyl-2-propenoates

Summary Methyl 2-cyano-3-dihalophenyl-2-propenoates, R₂C₆H₃CH=C(CN)CO₂CH₃ (R₂= 2,4-difluoro, 2,5-difluoro, 2,6-difluoro, 3,4-difluoro, 3,5-difluoro, and 2-chloro-6-fluoro), were prepared by the piperidine catalyzed Knoevenagel condensation of corresponding disubstituted benzaldehydes and methyl cyanoacetate. Novel copolymers of the propenoates and styrene were prepared at equimolar monomer feed by solution copolymerization in the presence of a radical initiator. The order of relative reactivity (1/r ₁) was 2,5-difluoro (2.11) > 2,6-difluoro (1.84) > 3,5-difluoro (1.71) > 2,4-difluoro (1.4) > 3,4-difluoro (0.65) > 2-chloro-6-fluoro (0.59). The copolymers were characterized by IR, ¹H and ¹³C NMR, GPC, DSC and TGA. High glass transition temperatures of the copolymers compared that of polystyrene indicates a substantial decrease in chain mobility of the copolymers due to the high dipolar character of the trisubstituted ethylene monomer unit. Received: 12 June 2000/Revised version: 12 September 2000/Accepted: 12 September 2000     

Phase composition,crystal structure and microwave dielectric properties of Mg2−xCuxSiO4 ceramics

In this work, the Mg_2-xCu_xSiO₄(x = 0–0.40) microwave dielectric ceramics were prepared using solid-state reaction method. Compared with the Mg₂SiO₄ sample, the Cu-substituted Mg samples could be sintered at a lower temperature. The Mg_2?xCu_xSiO₄ ceramics exhibit the composite phases of Mg₂SiO₄ and a small quantity of MgSiO₃. The Cu²⁺ ion presented a solid solution with the Mg₂SiO₄ phase and preferentially occupy Mg(1) site. The distortion of MgO₆ octahedron was modified by Cu²⁺ ions, resulting in a positive change in the temperature coefficient of resonance frequency (τ_f) values. Excellent microwave dielectric properties of ε_r = 6.35, high Qf of ～ 188,500 GHz and near zero τ_f = ?2.0 ppm/°C were achieved at x = 0.08 under sintering at 1250 °C for 4 h. Thus, the fabricated ceramics were considered as possible candidates for millimeter-wave device applications.     

Charge transfer copolymerization and properties of isopropyl methacrylate with acrylonitrile and methacrylonitrile

Isopropyl methacrylate (IPMA) with Acrylonitrile (AN) and Methacrylonitrile (MAN) copolymers of different copositions were prepared at 60°C and 80°C, respectively, using a mixture of n-Butylamine (nBA) and carbon tetrachloride (CCl₄) in dimethyl sulphoxide (DMSO) as a charge transfer (CT) initiator. The percentage composition of the copolymers was established by elemental analysis. The copolymerization reactivity ratios were computed by the Kelen–Tudos method. In both the systems, IPMA was found to be more reactive; the copolymers sequence was random in nature. The copolymers were characterized by IR, ¹H-NMR, ¹³C-NMR spectroscopy and intrinsic viscosity measurements in dimethyl formamide (DMF) at 30±0.1°C. The thermal behavior of the AN-IPMA copolymers was studied by thermogravimetry (TG) in air. The thermal stability increased, with increasing AN content in the copolymer chain. The solubility parameter of AN-IPMA copolymer was evaluated by studying the intrinsic viscosity in different solvents. The solubility parameter of the copolymer was found to be 9.7 (cal/cc)^1/2.     

Synthesis and properties of poly(2-adamantyl vinyl ether)-based optical plastics

Cationic polymerization of 2-adamantyl vinyl ether (2-vinyloxytricyclo[3.3.1.1^3,7]decane; 2-AdVE) and copolymerization of 2-AdVE with n-butyl vinyl ether (NBVE), 2-methoxyethyl vinyl ether (MOVE), or 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA), vinyl ethers containing a flexible chain or a polymerizable group, were performed to obtain poly(vinyl ether) plastics for optical use. With the living cationic initiating systems such as isobutyl vinyl ether–acetic acid adduct/ethylaluminum sesquichloride (IBEA/Et_1.5AlCl_1.5) or the hydrogen chloride/zinc chloride (HCl/ZnCl₂), all the obtained copolymers had unimodal and relatively narrow molecular weight distributions (polydispersity ratio: M _w/M _n = ~1.5 at high conversion) throughout the copolymerizations. These results indicate that the copolymerizations of 2-AdVE with the three comonomers led to the statistical copolymers without contamination of homopolymers. With BF₃OEt₂ as an initiator, homopolymer of 2-AdVE and poly(2-AdVE)-based polymers, poly(2-AdVE-stat-NBVE), poly(2-AdVE-stat-MOVE), and poly(2-AdVE-stat-VEEA), were produced with high-molecular weights (M _n = 31,800–116,000) in toluene at ?30 °C in quantitative yield within 10 min. They have excellent thermal stability owing to their high glass transition and thermal decomposition temperatures. The transparency (86–91 %) and refractive index (1.52–1.53) of the molded polymers are similar to those of conventional optical plastics such as poly(methyl methacrylate) (PMMA) and polycarbonate (PC), whereas their specific gravity (1.09–1.12) and water absorption (0.06–0.17 %) are significantly lower than those of PMMA and PC. In addition, the Abbe number of poly(2-AdVE), poly(2-AdVE-stat-NBVE), and poly(2-AdVE-stat-MOVE) exceeded 60 and was higher than those of PMMA and PC, indicating that the poly(2-AdVE)-based plastics are very suitable for optical lens.     

Crosslinking of poly(N-vinyl pyrrolidone-co-n-butyl methacrylate) copolymers for controlled drug delivery

Poly(N-vinyl pyrrolidone-co-n-butyl methacrylate) P(NVP-co-nBMA) copolymers containing high N-vinyl pyrrolidone content were crosslinked to increase their hydro-stable nature for controlled drug delivery. Diethylene glycol dimethacrylate (DEGDMA) and trimethylolpropane trimethacrylate (TMPTMA) were used as crosslinkers. The effect of crosslinker concentration and functionality on gel content, thermal stability and water uptake at 37 °C was investigated. The gel contents and thermal stability increased while water uptake decreased with increasing concentration and functionality of crosslinker. The copolymer crosslinked by TMPTMA showed good mechanical properties. The porous network structure of the copolymers was confirmed by scanning electron microscopic studies. Dexamethasone was selected as a model drug and its controlled release was observed for 22 days from TMPTMA crosslinked copolymer (NB91-T2) film, whereas 96 % drug was released in 35 days for DEGDMA crosslinked copolymer (NB91-D2) film. The kinetics of 10 h drug release identified first-order drug release for NB91-D2 and Higuchi kinetics for NB91-T2. The initial 60 % drug release followed non-Fickian diffusion mechanism. These results indicate the future application of NB91-D2 and NB91-T2 copolymer films as a drug carrier for implant coatings.