γ-甲基丙烯酰氧丙基三(三甲基硅氧基)硅烷的制备及其乳液聚合研究

通过 γ-甲基丙烯酰氧丙基三甲氧基硅烷 ( KH-5 70 )与三甲基氯硅烷共水解 ,进一步发生缩合反应 ,制备了γ-甲基丙烯酰氧丙基三 (三甲基硅氧基 )硅烷。并通过乳液聚合法制备了该单体的自聚乳液 ,对聚合工艺进行了初步探讨 ,用红外光谱对聚合产物进行了表征。同时 ,研究了乳化剂的种类及用量对反应的影响 ,发现采用有机硅乳化剂和阴离子乳化剂复配的乳化体系 ,可得到稳定性强、粒度适中的自聚乳液。     

新型支化有机硅与甲基丙烯酸甲酯共聚乳液稳定性的研究

用甲基丙烯酰氧基丙基三(三甲基硅氧基)硅烷(TR IS)与甲基丙烯酸甲酯进行了乳液共聚合,研究乳化剂的用量和配比、反应时间、单体的配比等对乳液稳定性,凝胶率,转化率的影响,用透射电镜测试了乳液的粒径。结果表明用有机硅改性表面活性剂,十二烷基硫酸钠(SDS)和1-丙烯基-2-羟基烷机磺酸钠(COPS-1)为复配乳化剂,在适宜条件下,可使有机硅共聚乳液胶粒达到纳米级分散,得到高硅含量的稳定乳液。     

Fabrication of contact lens containing high‐performance wire grid polarizer

Contact lenses containing high‐performance wire grid polarizers (WGPs) were fabricated. The base polymeric membrane was synthesized by copolymerization of 2‐hydroxyethyl methacrylate, 3‐[tris(trimethylsiloxy)silyl]propyl methacrylate, 1‐vinyl‐2‐pyrrolidinone, methyl methacrylate and ethylene glycol dimethacrylate. The nanopattern was formed by nanoimprint lithography using a UV‐curable rubber‐toughened epoxy resin on the base membrane. Two consecutive angled aluminium evaporations were performed on the nanopattern, followed by reactive ion etching to form the WGP. The WGP on the membrane was then covered by another layer of the base polymeric material to form the final contact lens. This membrane demonstrated high performance as a polarizer, confirmed by measuring transmittance of transverse magnetic polarized light and transverse electric polarized light. This membrane also demonstrated good performance as a contact lens in terms of modulus, water content and oxygen permeability. © 2017 Society of Chemical Industry     

Reversible addition fragmentation chain transfer polymerization of 3-[tris(trimethylsilyloxy) silyl] propyl methacrylate

Reversible addition fragmentation chain transfer (RAFT) bulk polymerizations of 3-[tris(trimethylsilyloxy)silyl] propyl methacrylate (TRIS) have been carried out at 60 °C, employing cumyl dithiobenzoate (CDB) and 2-cyanoprop-2-yl dithiobenzoate (CPDB) as mediating agents at concentrations ranging from 5.0×10⁻³ to 2.0×10⁻² mol l⁻¹. The monomer conversion vs. time evolution was followed via dilatometry and ¹H NMR spectroscopy. The CDB mediated polymerization displays RAFT agent concentration dependent inhibition and rate retardation phenomena, whereas the CPDB mediated polymerization process is less susceptible to rate retardation and inhibition effects. The different behavior of CDB and CPDB in TRIS polymerization is most likely due to the increased stability of the intermediate macroRAFT radicals in the CDB mediated process. The generated RAFT polymers were analyzed via size exclusion chromatography indicating linear macromolecular growth with respect to monomer conversion and low polydispersities (PDI<1.15) up to high monomer to polymer conversion (>90%).     

Dispersion polymerization of styrene in supercritical CO2 in the presence of non-fluorous random copolymeric stabilizers

The non-fluorous random copolymers, poly (3-[tris(trimethylsilyloxy)silyl]propyl methacrylate-co-2-dimethylaminoethyl methacrylate) (poly(SiMA-co-DMAEMA)) and poly (3-[tris(trimethylsilyloxy)silyl]propyl methacrylate-co-diisopropylaminoethyl methacrylate) (poly(SiMA-co-DPAEMA)) were prepared with different comonomer compositions and utilized as stabilizers in the dispersion polymerization of styrene in supercritical carbon dioxide (scCO₂). The copolymers were found to provide an effective stabilization on the polystyrene (PS) latexes in scCO₂. Poly(SiMA-co-DMAEMA) (71:29) were proved to be optimal among (86:11), (71:29), and (57:33) comonomer compositions to produce micron-sized spherical PS particles with higher yields. Poly(SiMA-co-DPAEMA) having higher methyl branching in the DPAEMA pendant group provided a better stabilization compared to poly(SiMA-co-DMAEMA). The effect of varying concentration of stabilizer and monomer upon the polymerization yield, molar mass, and morphology of PS have been investigated.     

Novel synthesis of a hindered trisubstituted dehydroalanine derivative and its copolymerization with methyl acrylate

Summary The new monomer N-methy1-N-butyryldehydroalanine methyl ester was obtained in good yield by N-methylation and base catalyzed ring opening of racemic 2-propy1-4-methoxycarbonyl-2-oxazoline. The oxazoline was prepared in high yield from (R,S)-serine methyl ester hydrochloride and ethyl butyroimidate. Attempted radical and anionic homopolymerization of purified monomer failed. Radical copolymerization with methyl methacrylate was also unsuccessful, although copolymerization with the less hindered methyl acrylate did produce copolymer as determined by high resolution ¹³C NMR. Unsubstituted N-butyryldehydroalanine methyl ester was prepared by an alternative route and was shown to spontaneously homopolymerize to high polymer. Space-filling models of the monomers indicate steric hindrance for approach of the N-methylated monomer to the active chain end, consistent with difficult homopolymerization.     

Synthesis of chiral polymers containing the acetoxybornyl group and their applications on the asymmetric induction

Optically active 2-endo-actoxy-5-endo-bornyl methacrylate (ABMA) was prepared from (+)-camphor. The homopolymerization of ABMA and copolymerization of ABMA with achiral methyl methacrylate (MMA) or styrene (St) were carried out with 2,2′-azobisisobutyronitrile (AIBN) in benzene. Effects of temperature, solvents, and reaction time on the copolymerization were discussed. The monomer reactivity ratios(r₁, r₂) for poly(ABMA-co-MMA) and poly(ABMA-co-St) and Q and e values for the chiral ABMA in the copolymerization systems were evaluated by the Fineman—Ross method. The absolute value of the specific rotation of poly(ABMA-co-MMA) increased with increasing ABMA unit content. A small deviation from linearity was observed, which suggests that asymmetry is not introduced into the copolymer main chain. Temperature and solvent effects on the specific rotation of the chiral homopolymer and copolymers were investigated. The results suggest that the chiral polymers synthesized in this investigation did not show a strong preference for a particular helical conformation. Applications of the chiral polymers on the asymmetric addition of n-butyllithium to aldehydes were also discussed.     

Poly(BMA-co-NVP)/NiS core-shell hybrid materials via Interfacial-initiated miniemulsion copolymerization and gamma-irradiation

In this work, N-butyl methacrylate (BMA)/N-vinyl-2-pyrrilidone (NVP) amphiphilic core-shell nanoparticles were successfully prepared via miniemulsion copolymerization, the emulsion was initiated by the redox initiation couple of cumene hydroperoxide (CHPO) and ferrous sulfate hydrate (FS). The synthetic waterborne polyurethane (WPU) was used as surfactant and hexadecane (HD) as co-stabilizer, respectively. FTIR and XPS were used to confirm the occurrence of copolymerization between two monomers. TEM and DLS were used to observe the particle morphology and determine the particle size and its polydispersity index (PDI). It was found that the core-shell poly(BMA-co-NVP) nanoparticles prepared via interfacial-initiated miniemulsion copolymerization (IMEP) had relatively small diameters (40–120 nm) and narrowly particle size distribution (0.066–0.243). Only about 2 wt% surfactants based on the solution was enough to prepare a stable miniemulsion. The results demonstrated that IMEP prompted the copolymerization of water-soluble NVP monomer with oil-soluble BMA monomer to form core-shell nanoparticles. The effects of surfactant and co-stabilizer affect on the miniemulsion copolymerization were discussed. All the results indicate that the fabrication amphiphilic core-shell nanoparticles via IMEP were successful. Then the poly(BMA-co-NVP)/NiS hybrid materials were fabricate via the reaction of NiSO₄ and CH₃CSNH₂ on the copolymers surface under ⁶⁰Co γ-irradiation at room temperature and ambient pressure. The hybrid materials were characterized by FESEM.     

Polymerization of an Acetoxyvinyl Substituted Chlorocyclophosphazene

The vinyl acetate derivative, gem-isopropyl-2-(-acetoxyvinyl)tetrachlorocyclotriphosphazene (1), has been used in radical homopolymerization and copolymerization reactions with methyl methacrylate, (MMA) and styrene. The 1,1-disubstituted olefin did not undergo radical homopolymerization. Copolymers derived from MMA and 1 contained only low amounts (<2 mol%) of 1. A maximum incorporation of 20 mol% of phosphazene monomer was achieved with styrene as comonomer. The data obtained in low- and high-conversion copolymerizations with styrene were used to calculate the monomer reactivity ratios. The results of the calculations show that the terminal model is not operative. Calculation for the penultimate model with r ₂=0 resulted in r ₁ and r₁ values of 2.8±0.2 and 0.7±0.1, respectively. For the hypothetical homopolymer of 1 a T _g value of 441 K was calculated. All the copolymers with styrene exhibit flame-retardant properties.     

Synthesis of novel functionalized methacrylate copolymers and their copolymerization kinetics,thermal stability,and biocidal properties

In the first step of this study, 2-[(methoxy-1,3-benzothiazole-2-yl)amino]-2-oxoethyl methacrylate (MBAOM) monomer was synthesized and characterized. Then, a series copolymers were obtained by free-radical copolymerization method of MBAOM and glycidyl methacrylate, which is a commercial monomer at 65°C in 1,4-dioxane solvent. Structural characterizations of synthesized monomer and copolymers were carried out using Fourier transform infrared spectrophotometer and nuclear magnetic resonance spectroscopy (¹H and ¹³C-NMR) instruments. The composition of the copolymers was estimated by elemental analysis. The thermal behaviors of all the polymers have been investigated using the differential scanning calorimetry and the thermogravimetric analysis. A kinetic study of the thermal decomposition of copolymers was investigated using thermogravimetric analyzer with non-isothermal methods selected for analyzing solid-state kinetics data. The activation energy (E_a) values were calculated via Kissinger and Ozawa models in a period of α = 0.10–0.80. Photostability of the copolymers was investigated. Also, the biological activity of the copolymers against different bacterial and fungal species has been investigated.     

Polymerization of Cyclophosphazenes with Spriocyclic Methacrylate Containing Substituents

The radical addition polymerization and copolymerization of the cyclophosphazene monomers with spirocyclic methacrylate containing substituents, spiro(2,3-dioxypropylmethacryloyl)tetrachlorocyclotriphosphazene, N₃P₃Cl₄[OCH₂CH(OC(O)=CH₂)O] (1) and spiro((2-methyl-3-oxy-2-(oxymethyl)propyl)methacryloyl)tetrachlorocyclotriphosphazene, N₃P₃Cl₄[OCH₂CMe(CH₂OC(O)=CH₂)CH₂O] (2), has been investigated. In the case of 1, homopolymerization using AIBN as the initiator yielded only cross-linked solids. Copolymerization of 1 with methyl methacrylate was accomplished using VAZO 52 under milder initiation temperature. GPC of copolymer suggested a significant amount of chain transfer. Homopolymerization of 2 gave low isolated yields of the homopolymer but copolymerization with methyl methacrylate yielded the expected copolymers. The reactive chlorine atoms in the copolymers of 2 can be replaced by trifluoroethoxide or methyl amine. Thermal properties of the copolymers were examined by DSC, TGA and pyrolysis mass spectrometry.     

Synthesis of NIPAAm-based polymer-grafted silica beads by surface-initiated ATRP using Me4Cyclam ligands and the thermo-responsive behaviors for lanthanide(III) ions

The applicability of atom transfer radical polymerization (ATRP) to the copolymerization of N-isopropylacrylamide (NIPAAm) with N-vinyl-2-pyrrolidone (NVP) was examined in CuCl/CuCl₂-catalyst system using tris[2-(dimethylamino)ethyl]amine (Me₆TREN) and 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (Me₄Cyclam) as ligands. In the Me₆TREN system, less reactive NVP not only does not quantitatively copolymerize but also interferes with homopolymerization of NIPAAm units. In contrast, the Me₄Cyclam system under heating was more active, although the controllability for polymer homogeneity is lower than Me₆TREN system. The application of active Me₄Cyclam system to surface-initiated ATRP has successfully prepared silica beads surface-modified with NIPAAm copolymers of NVP and 4-vinylpyridine (VPy). The thermo-responsive behavior of surface-grafted NIPAAm-based polymers was investigated for lanthanide trivalent ions (Ln(III)) in different pH solutions. In the weak acidic solutions of pH = 5.4–5.6, all the surface-grafted polymers including poly(NIPAAm) exhibited only adsorption behavior with regular selectivity (Eu³⁺ > Sm³⁺ > Nd³⁺ > Ce³⁺ > La³⁺) below the phase-transition temperatures. In the more acidic solution of pH = 2.9, the surface-grafted poly(NIPAAm) and NVP copolymers exhibited adsorption and desorption behaviors below and above the phase-transition temperatures, while VPy copolymers exhibited only adsorption independent of temperature change. Furthermore, the adsorption capacity of all the surface-grafted polymers was deteriorated by the lowering of pH. The observed desorption and the deterioration of adsorption capacity suggest the weakening of adsorption strength for Ln(III) in low pH solutions. In this study, a possible adsorption/desorption mechanism of Ln(III) on surface-grafted NIPAAm-based polymers is discussed.     

Gas permeability of cross-linked poly(ethylene-oxide) based on poly(ethylene glycol) dimethacrylate and a miscible siloxane co-monomer

Pure gas permeability coefficients of a series of copolymers based on polar, hydrophilic poly(ethylene glycol) dimethacrylate, n = 14 (PEGDMA) and siloxane-based co-monomer, [methyl bis(trimethylsiloxy)silyl] propyl glycerol methacrylate (SiGMA) are reported. SiGMA is miscible with PEGDMA and able to form homogeneous films. SiGMA contains a bulky siloxane-based end group, which acts to increase permeability, and an -OH pendant group, which increases miscibility with polar co-monomers, such as PEGDMA. As the SiGMA content in these copolymers increases to 53 vol%, CO₂ permeability increases from 95 to 255 barrer, while CO₂/N₂ and CO₂/H₂ pure gas selectivities decrease from 58 to 20 and 6.4 to 3.2, respectively. At the same time, fractional free volume of the copolymer increases from 0.118 to 0.140. Comparisons to a similar copolymer system are made to rationalize the permeability and selectivity trends of this series of copolymers.     

Stabilization of the living end in the anionic polymerization of 2-(trimethylsiloxy)ethyl methacrylate

Summary In an anionic polymerization of 2-(trimethylsiloxy)ethyl methacrylate (Pro HEMA), the loading rate of the monomer was found to influence the polymerization. When the monomer loading was run quickly via a dropping funnel, the ProHEMA polymerization occurred quantitatively to form poly(ProHEMA) with a narrow molecular weight distribution (MWD). Based on the results, we propose a mechanism in which monomer molecules surrounding the propagating species take part, viz, the surrounding monomer molecules prevent a possible termination reaction. In the presence of LiC1 for ProHEMA polymerization, a polymer with a rather narrower MWD was obtained.     

Synthesis of well‐defined comb‐like amphiphilic copolymers with protonizable units in the pendent chains: 1. Preparation of narrow polydispersity copolymers of methyl methacrylate and 2‐hydroxyethyl methacrylate by atom‐transfer radical polymerization

Well‐defined methyl methacrylate (MMA) and 2‐(trimethylsiloxy)ethyl methacrylate (Pro‐HEMA) copolymers were prepared by atom‐transfer radical polymerization(ATRP), using CuCl/2,2′‐bipyridine as catalytic system and p‐toluenesulfonyl chloride as initiator. ATRP process of MMA and Pro‐HEMA was monitored by ¹H NMR, and the kinetic curves of the MMA/Pro‐HEMA copolymerization were plotted in terms of the ¹H NMR data. At low content of Pro‐HEMA in the feed composition, the copolymerization can be well controlled with the molecular weight, polydispersity and the monomer distribution in the copolymer chain. With the increase of Pro‐HEMA content in the feed mixture, the composition of the final copolymer deviates from the composition of the feed mixture gradually, and gradient copolymers of MMA/Pro‐HEMA can be obtained. Through the hydrolysis process, well‐defined copolymers of MMA/HEMA were obtained from poly(MMA/Pro‐HEMA). Copyright © 2003 Society of Chemical Industry     

Microspheres of copolymeric <Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone and 2-ethoxyethyl methacrylate for the controlled release of nifedipine

Free radical copolymerization of N-vinyl-2-pyrrolidone (NVP) with 2-ethoxyethyl methacrylate (EOEMA) was carried out with 2,2′-azobisisobutyronitrile (AIBN) initiator in 1,4-dioxane solvent at 60 °C. The resulting copolymers were characterized by FTIR, ¹H-NMR and ¹³C-NMR methods. Microspheres were prepared by varying the amount of NVP with respect to EOEMA. Nifedipine (NFD), a water-insoluble antihypertensive drug, was loaded into these microspheres by the oil in water emulsion technique followed by solvent evaporation. The effect of the proportion of NVP in the NVP/EOEMA copolymer on the controlled release of NFD from the microsphere matrix was investigated. Scanning electron micrographs (SEM) of the microspheres indicated spherical shapes in the size range 17–47 μm, even after loading with NFD. In vitro studies of the release of NFD from the NVP/EOEMA microspheres in pH 7.4 medium showed that the rate of NFD release was enhanced when the NVP content of the copolymer was high; the size of the microspheres also increased with increasing NVP content of the copolymer. Release data were analyzed using an empirical relation in order to elucidate the kinetics of the NFD release. This analysis indicated that a Fickian transport mode operates in this system.     

Antiinflammatory polymer-bound steroids for topical applications. I. Synthesis and characterization

Covalent binding of hydrocortisone and dexamethasone to hydrophylic biocompatible macromolecular carriers through hydrolizable carbonate linkage was investigated according to two complementary strategies. (a) Radical copolymerization of hydrocortisone-²¹C-vinylcarbonate with N-vinylpyrrolidone (NVP,60°C), or N-[tris(hydroxymethyl)methyl]acrylamide (THMMA, 50°C) in dimethylacetamide solution: In spite of a nearly zero reactivity ratio for the steroid monomer which behaves as a degradative transfer agent—C_T ～ 5.7 × 10^?2 and 6.8 × 10^?3 for NVP and THMMA, respectively–this process may afford fairly high molecular weight polymers (M?_w ? 10⁴–10⁵) with high enough hydrocortisone content (0.03–0.10 mole.fraction). (b) Condensation of the hydrocortisone or dexamethasone-²¹C-chloroformates onto poly(oxyethylene glycol) (M?_n = 6220) or hydroxypropylcellulose (HPC, M?_w = 1.35 × 10⁵) in tetrahydrofuran solution (30°C): This straightforward process is of low efficiency (yields >50%), and only HPC derivatives show good chemical homogeneity.     

Radiation-induced graft copolymerization of styrene to cellulose

The radiation-induced graft copolymerization of styrene to cellulose has been studied in vacuo at 30°C and at dose rates from (0.37 to 8.73) × 10^?2 W/kg. Dioxan was used as solvent for monomer and polystyrene homopolymer, and water (2% total volume) was incorporated as swelling agent for cellulose. The concentration of styrene in the bulk medium was varied from 0.432 to 3.46 moles/l., and the rates of both grafting and homopolymerization were shown to be proportional to [monomer] · [intensity]^1/2. The value of 3.3 × 10^?4 l. mole^?1 sec^?1 derived for k_p²/k_t in homopolymerization is similar to that for normal free-radical polymerization of styrene. However, reduced termination during grafting yielded a much higher value (58 l. moles^?1 sec^?1). Degradation of cellulose in the absence of monomer was followed viscometrically, and values of 13.5 and 24.6 were derived for G (scission) in vacuo and in air, respectively.     

Processes involved during radiation grafting of N‐vinyl pyrrolidone onto poly(ethylene terephthatate) fabric

Kinetics of radiation grafting of N‐vinyl pyrrolidone (NVP) onto poly(ethylene terephthalate) (PET) fabric revealed the existence of four different processes. These are as follows: the grafting, the homopolymerization, the degradation, and the diffusion. The grafting process was followed by the increase in weight with the increase in irradiation time (t), while the homopolymerization and the degradation processes were evaluated from changes in the square root of the specific viscosity of the irradiated monomer solution (√η_sp) with the increase in t. All processes were carried out at different NVP concentrations, different irradiation temperatures (T), and a dose rate 1.31 Gy s^?1. All processes followed first‐order kinetics except the degradation process that followed a 0.6‐order. The rate (R) and rate constant (k) of grafting and diffusion processes were found to increase with the increase in T, while the homopolymerization and degradation processes showed negative temperature dependence. The sum of R of the four processes was proportional to the initial NVP concentration, while k of the four processes was independent of T and has a value of 0.674 min^?1. The respective apparent activation energies of 24.0, 6.24, 6.84, and 2.5 kJ mol^?1 were calculated for the four processes. The NVP molecules participated in each process and their energies were evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3009–3022, 2006     

Enantioface differentiation by chiral polymers containing dimethylaminobornyl moieties

Chiral monomers cis,endo-3-dimethylamino-2-bornyl methacrylate (DABM) and N,N-dimethyl[cis,endo-2-(2-vinyloxy-ethoxy)-3-bornyl]amine (DVEBA) were synthesized from (+)-camphor. The homopolymerization of both DABM and DVEBA, and the copolymerization of both chiral monomers with achiral methylmethacrylate (MMA) and styrene (St) were carried out with 2,2-azobisisobutyronitrile (AIBN) in various organic solvents. Effects of temperature, solvents, reagent molar ratio and reaction time on the polymerizations were studied. Dependences of the feeding concentration and reaction conditions on the specific rotation of the chiral copolymers were investigated. Enantioface differentiation by using the chiral polymers having dimethylaminobornyl moieties synthesized in this investigation were investigated. Effects of temperature and solvent on the asymmetric induction were also studied. © 1994 John Wiley & Sons, Inc.