Reactive and Functional Polymers (v.70, #3)

Thermosensitive copolymer with cobalt phthalocyanine and catalytic behavior based on adjustable LCST by Wangyang Lu; Baoyan Zhao; Nan Li; Yuyuan Yao; Wenxing Chen (135-141).
Thermosensitive polymers with metallophthalocyanine were prepared by immobilizing cobalt tetra(2,4-dichloro-1,3,5-triazine)aminophthalocyanine (Co-TDTAPc) on poly(N-isopropylacrylamide) (PNIPA) and copolymers of N-isopropylacrylamide (NIPA) with acrylamide (AM) (P(NIPA-co-AM)) to obtain Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM). Examination of the thermosensitive behavior of these polymers showed that the proportion of AM in Co-TDTAPc–P(NIPA-co-AM) had a significant effect on the low critical solution temperature (LCST) in aqueous solution. The LCST of Co-TDTAPc–P(NIPA-co-AM) was adjustable from 34.5 °C to 90.0 °C by changing the AM molar fraction from 0% to 40%. The copolymers showed a high level of catalytic activity on the oxidation of 2-mercaptoethanol in the homogeneous phase when the reaction temperature was below the LCST, and the copolymers could be precipitated and recovered by heterogeneous separation when the temperature was above the LCST. Compared to Co-TDTAPc–PNIPA, the catalytic system with Co-TDTAPc–P(NIPA-co-AM) is able to maintain homogeneity at a higher temperature due to the higher LCST of the copolymers. In addition, strong salting-out salts, such as NaCl and Na2SO4, can decrease the LCST of the copolymers dramatically and obviate the need for more heat to drive the catalytic reaction system to achieve heterogeneous separation. Co-TDTAPc–P(NIPA-co-AM) was stable and remained efficient during repetitive test cycles with no obvious decrease of catalytic activity.
Keywords: Phthalocyanine; Thermosensitive copolymers; N-isopropylacrylamide; Acrylamide; Phase separation;

Kinetic evaluation of phenol/aniline mixtures adsorption from aqueous solutions onto activated carbon and hypercrosslinked polymeric resin (MN200) by César Valderrama; Joan I. Barios; Michelle Caetano; Adriana Farran; José Luis Cortina (142-150).
Kinetic adsorption of phenol and aniline from aqueous solution onto activated carbon and hypercrosslinked polymeric resin MN200 were evaluated in single and binary system. Larger phenol and aniline uptakes were observed for activated carbon in single as well as binary system, which can be attributed to the better physical properties of activated carbon, for instance larger surface area and micropore area. The kinetic experimental data was properly fitted by the pseudo-first and pseudo-second-order rate equations. A synergetic effect between solutes was observed since phenol and aniline sorption kinetic in binary system was faster than the individual sorption of each solute in single system, as well as a slight increase in the kinetic parameters obtained in binary system. The particle diffusion rate was defined as the rate limiting mechanism in the singles and binary system for phenol and aniline kinetic adsorption on both adsorbents. Two steps were markedly defined by the Weber and Morris intraparticle diffusion analysis for phenol and aniline onto both adsorbents. In binary systems, the intraparticle diffusion was influenced by the physical properties of adsorbents.
Keywords: Kinetic adsorption; Activated carbon; Resin MN200; Binary; Phenol/aniline; Diffusion coefficient;

In this paper a study of correlations between the microstructure of well defined poly(ε-caprolactone) (PCL) samples and their physical properties such as thermal degradation, crystallization kinetics and melting behavior is described. The PCL samples were obtained in the presence of the compound benzyl-methoxy-bis(2,4,6-triisopropylphenyl)tin (1), acting as single-site and living initiator, as well as in the presence of compounds Tip2SnRR′ [Tip = 2,4,6-triisopropylbenzene; R = R′ = CHCH2 (2); R = CH2Ph, R′ = Br (3)] activated by ionizing agents. PCL samples having different end groups, molecular weight and molecular weight distribution were obtained. The samples were fully characterized by GPC and NMR. The thermal degradation of the synthesized samples were studied by thermogravimetric analysis (TGA) in air flow. The experimental results suggested that the presence of ester chain end groups has a beneficial effect on the thermal stability of the PCL samples, independently on the molecular weights and molecular weight distribution. The crystallization behavior was studied in isothermal conditions at 37 °C, 40 °C, and 43 °C through differential scanning calorimetry (DSC). In this case, either the molecular weight (M w) or the polydispersivity index (PDI) have a significant effect on the kinetics of crystallization of PCLs.
Keywords: ε-Caprolactone; Tin compounds; Ring opening polymerization; Thermal degradation;

A pH-, thermo-, and glucose-, triple-responsive hydrogels: Synthesis and controlled drug delivery by Lu Wang; Mingzhu Liu; Chunmei Gao; Liwei Ma; Dapeng Cui (159-167).
In this work, a series of hydrogels were prepared by copolymerization of (2-dimethylamino) ethyl methacrylate (DMAEMA) and 3-acrylamidephenylboronic acid (AAPBA). The structure of the resultant hydrogels was studied by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The experimental results from swelling studies revealed that the hydrogels displayed definite glucose sensitivity under physiological conditions, as well as sharp changes in the mesh size of their network as a function of the pH and temperature of the swelling media. Bovine serum albumin (BSA) was selected as a model compound when examining protein release from hydrogels. The results suggested that the temperature, pH and glucose concentration of buffer solutions greatly influenced release profiles.
Keywords: Hydrogels; Multi-responsive; Controlled drug release; 3-Acrylamidephenylboronic acid; (2-Dimethylamino) ethyl methacrylate;

Silver nanoparticles in polyvinylpyrrolidone grafted natural rubber by N.H.H. Abu Bakar; J. Ismail; M. Abu Bakar (168-174).
Polyvinylpyrrolidone grafted natural rubber (PVP-g-NR) latex was used as matrix to synthesize silver nanoparticles. The average diameter of the silver nanoparticles is 4.1 nm. The modified natural rubber was previously formed via in situ polymerization of N-vinyl-2-pyrrolidone (NVP) in natural rubber latex (NRL) using cumene hydroperoxide (CHP) and tetraethylenepentamine (TEPA) as a redox initiator. The evidence of PVP grafted rubber particles was demonstrated by extraction as well as gravimetric and FTIR studies. Transmission electron microscopy (TEM) studies of the Ag+/PVP-g-NR films after exposure to UV light, revealed distinct layers comprised of PVP-stabilized silver particles surrounding the rubber particle. This confirms the grafting of PVP, which stabilizes the silver particles as well as the rubber particles in a role that is similar to that of the protein in our previous work.
Keywords: Polyvinylpyrrolidone grafted natural rubber; Silver nanoparticles; UV irradiation;

Syntheses and self-assembly of novel polyurethane–itaconic acid copolymer hydrogels by Guichang Jiang; Xinlin Tuo; Dongrui Wang; Junpeng Liu (175-181).
Novel physically crosslinked polyurethane–itaconic acid (PU–I) copolymer hydrogels were synthesized by the macroiniferter-controlled radical polymerization method. The structures of the PU–I copolymer hydrogels were characterized by 1H NMR, FTIR, GPC, and DSC. The water contact angles and self-assembly of the PU–I copolymer hydrogels have been investigated. The results revealed that PU–I copolymer hydrogels have good hydrophilicity, so the water contact angles of polyurethane could be easily adjusted by controlling the content of the hydrophilic vinyl monomers. The PU–I copolymer hydrogels were subjected to solvent-induced self-assembly in THF + water to construct a variety of morphologies. The morphology of the PU–I copolymer hydrogels’ self-assembly was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the mechanism of self-assembly was investigated.
Keywords: Biomaterials; Biopolymers; Polymerization; Functional polyurethanes; Self-assembly;

A new monomer, N,N′-bis(4-phenoxybenzoyl)-m-phenylenediamine (BPBMPD), was prepared by condensation of m-phenylenediamine with 4-phenoxybenzoyl chloride in N,N-dimethylacetamide (DMAc). Novel soluble aromatic poly(ether amide amide ether ketone ketone)s (PEAAEKKs) were synthesized by electrophilic Friedel–Crafts solution copolycondensation of BPBMPD with a mixture of terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC) in the presence of anhydrous aluminum chloride and N-methylpyrrolidone (NMP) in 1,2-dichloroethane (DCE). The influences of reaction conditions on the preparation of polymers were examined. The polymers obtained were characterized by different physico-chemical techniques such as FT-IR, DSC, TGA, and wide-angle X-ray diffraction (WAXD). All the polymers were amorphous and the solubility of the polymers was improved by the incorporation of 1,3-dibenzoylaminobenzene moieties in the main chain. Thermal analyses showed that the polymers had high T gs of 220–231 °C and exhibited high thermal stability. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 102.9–108.5 MPa, Young’s moduli of 2.44–2.86 GPa, and elongations at break of 9.8–13.7%.
Keywords: Poly(aryl ether ketone); Electrophilic solution polycondensation; Terephthaloyl chloride; Isophthaloyl chloride; Thermal property;

In this work, we present the results of a kinetic study of the surface modification of the carboxyl group of poly(ethylene-co-acrylic acid) into acyl chloride. Reaction temperature and time, concentration of the reactants, kind of agitation have been changed in order to understand their effect on the conversion. A study on the penetration of the reaction inside the sample bulk was also performed. The results indicate that, when short reaction times are adopted, the reaction limits to the outer layers of the samples and, in this case, on increasing the temperature, the concentration of the reactants and the stirring allows having a faster kinetic. At longer reaction times, the reaction penetrates deep inside the sample (several tens of microns) and the influence of the above mentioned variables on the kinetic is very low.The results, obtained by direct FTIR, ATR-FTIR, SEM–EDX and contact angle measurements, were confirmed and corroborated by theoretical estimations.
Keywords: Poly(ethylene-co-acrylic acid); Surface modification; Functionalization;