Summary: A novel, stabilizer‐free dispersion polymerization with alkyl esters as reaction media gives uniform alternating microspheres of maleic anhydride (MAn)/vinyl acetate (VAc) copolymer. The diameter of the copolymer microspheres could be precisely controlled from 80 to 750 nm by changing the monomer concentration or feed ratio. Moreover, this new type of copolymer microspheres with reactive anhydride groups on the surface has good solubility in common nontoxic solvents such as water and ethanol.SEM image of the powder surface of copolymer microspheres formed at [MAn] = [VAc] = 1.5 M.imageSEM image of the powder surface of copolymer microspheres formed at [MAn] = [VAc] = 1.5 M.

Triphenylene-containing 1-decynes with different alkyl chain lengths and their polymers are synthesized and the effects of the structural variables on their mesomorphic properties are investigated. The monomers [HCϵC(CH 2 ) 8 CO 2 C 18 H 6 (OC m H 2mþ1 ) 5 ; m ¼ 4-9] are prepared by consecutive etherization, coupling, and esterification reactions. The monomers form columnar phases at room temperature. The polymerizations of the monomers are effected by [Rh(nbd)Cl] 2 , producing soluble polymers in high yields (up to 84%). The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, DSC, POM, and XRD analyses. All the polymers are thermally stable, losing little of their weights when heated to 300 8C. The isotropization temperature of the polymers increases initially with the length of alkyl chain but decreases on further extension. Although the polymers with shorter and longer alkyl chain lengths adopt a homogeneous hexagonal columnar structure, those with intermediate ones form mesophases with mixed structures.

A novel dispersion copolymerization of maleic anhydride (MAn) and vinyl acetate (VAc) without adding stabilizer is developed, which gives uniform copolymer microspheres with tunable sizes. Some principal factors affecting the microspheres, such as reaction time, monomer concentration and feed ratio, reaction media, and cosolvent, were investigated. It was found that the stabilizer‐free dispersion copolymerization of MAn and VAc is a rapid process, and the particle size grows in accordance with the evolution of polymerization. The chemical composition of the copolymer microspheres was characterized by FT‐IR and 13C NMR spectroscopies. Over a wide range of monomer concentrations, the microspheres can always be formed and stably dispersed, with uniform sizes ranging from 180 nm to 740 nm. The yield of copolymer microspheres reaches a maximum at 1:1 feed ratio of MAn to VAc, owing to the alternating copolymerization between the binary monomers by a known charge‐transfer‐complex mechanism. However, the diameter of microspheres drastically increases when MAn content is enhanced. Only some specific alkyl ester solvents, such as n‐butyl acetate, isobutyl acetate, n‐amyl acetate, are desirably fit for this unique stabilizer‐free dispersion polymerization. Furthermore, we found that when some acetone is added as a cosolvent, the copolymer microspheres can still be formed, with much larger diameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3760–3770, 2005

Summary: The polymerization features of the novel stabilizer‐free dispersion copolymerization of MAn and VAc were studied. It was found that the dispersion copolymerization of MAn/VAc is a fairly rapid process, which starts from a slow solution polymerization (below 10% conversion, Stage I) and follows a drastic increase of polymerization rate (10–80% conversion, Stage II) due to the known gel effect. Such process was accompanied by the increase of molecular weight of the copolymer formed ($\overline M _{\rm n}$ from 1.2 × 104 to 3.8 × 104 g · mol−1) and the broadening of the molecular weight distribution ($\overline M _{\rm w} /\overline M _{\rm n}$ from 2.4 to 8.0). Ea of Stage I was determined to be 76.7 kJ · mol−1, while the value of Stage II was 64.7 kJ · mol−1. The lower Ea in Stage II than that in Stage I suggests that there exists a shift of polymerization locus from the solution phase to the particle phase. Moreover, we found that the initial rate of polymerization increased with monomer concentration as well as initiator concentration, following the relationship (Rp)i ∝ [MAn + VAc] · [BPO]. This further implies that the dispersion copolymerization mainly proceeds as a solution polymerization in the very early stage.Evolutions of the stabilizer‐free dispersion copolymerization of MAn and VAc with butyl acetate as reaction medium and the solution copolymerization with methyl propyl ketone as solvent.magnified imageEvolutions of the stabilizer‐free dispersion copolymerization of MAn and VAc with butyl acetate as reaction medium and the solution copolymerization with methyl propyl ketone as solvent.

ABSTRACT:A novel antibacterial material with surface immobilized polyvinylpyrrolidone-iodine complex was synthesized facilely by a two-step approach. First, N-vinylpyrrolidone (NVP) was photografted onto polymeric substrates, and subsequently the surface-grafted polyvinylpyrrolidone (PVP) underwent complexation of iodine. In the UV-induced photografting process, PVP was efficiently grafted onto the polypropylene (PP) film surface by a unique film interlayer photopolymerization (FIP) technique; the grafting yield (Y g ) could be controlled by varying the irradiation time or the monomer concentration. Further, we demonstrated that the grafted PVP chains could readily perform the complexation reaction with iodine as the homopolymer PVP does, which was characterized by UV-vis spectroscopy. The antibacterial activity of the modified polymer against Escherichia coli, Staphylococcus aureus, and Candida albicans was investigated. The results show that the modified PP film with surface-immobilized PVP-I complex has a desirable antibacterial property, with broad spectrum and high efficiency.

Summary: A polymeric surface with desirable wettability and versatile reactivity was facilely fabricated by UV‐induced surface photografting of N‐vinylpyrrolidone (NVP)/maleic anhydride (MAn) binary monomers, with polypropylene (PP) film as a model substrate. It was found that the photografting process of NVP/MAn is much faster than that of individual NVP or MAn; both the grafting efficiency (Eg) and grafting yield (Yg) reach a maximum at around 1:1 molar feed ratio of NVP to MAn. These results indicate that the electron donor‐acceptor monomers can synergistically promote surface photografting by a known charge‐transfer‐complex (CTC) mechanism. Moreover, the grafted NVP and MAn units cooperatively enhance the surface hydrophilicity; the water contact angle of the modified surface drastically decreases from the original 99.4° to less than 36° within 30 s of irradiation time. Subsequently, we demonstrated that the surface‐grafted succinic anhydride groups could readily perform a variety of organic reactions such as acidic/alkaline hydrolysis and esterification, which is expected to facilitate further surface functionalizations. Besides, the complexing reaction of surface pyrrolidone groups with iodine was investigated, which was followed by UV‐vis spectroscopy. The antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans show that this unique iodine‐complexated surface has desirable antimicrobial property.Surface photografting of NVP/MAn and post reactions of surface‐grafted anhydride groups and pyrrolidone groups.imageSurface photografting of NVP/MAn and post reactions of surface‐grafted anhydride groups and pyrrolidone groups.

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ABSTRACT:Maleic anhydride (MAH) was readily grafted onto polypropylene (PP) film by means of introducing the electron donor monomer n-butyl vinyl ether (n-BVE), via two-step method. In the first step, the semibenzopinacol (SBP) groups were introduced onto the film surface under UV irradiation, and they were subsequently detected by both gravimetric method and UV spectra. In the second step, the "dormant" SBP groups were activated and cleaved from the substrate under heat, resulting in the formation of surface free radicals (grafting points) and the immediate initiation of graft polymerization; the temperature required for this process was found to be around 80• C. The grafting resultsshow that the grafting yield (Y g ) of two-step method can be much higher than that of one-step method, and that the novel electron donor-acceptor grafting system is much more effective than that of pure MAH. Properly speaking, the Y g value could reach as high as 180% within 1 h, and the density of polar groups (D p ) on the substrate was 49.5 µmol cm −2 correspondingly. Besides, the maximum Y g can be always attained at 1:1 molar feed ratio of MAH to BVE, indicating that the facile grafting process is attributed to the formation of charge transfer complex (CTC) between the binary monomers. Another significant result is that the good affinity of solvent towards substrate, and especially the desirable solubility for the graft chains are both preferable to heterogeneous graft polymerization. In addition, some phenomena characterizing "living" graft polymerization were revealed in this particular grafting system, which is expected to favor the control of the length and chemical structure of the graft chains.