Photoactive,liquid‐crystalline,hyperbranched benzylidene polyesters: Synthesis and characterization

A novel photoactive, liquid‐crystalline, hyperbranched benzylidene polyester (PAHBP) was synthesized from a dilute solution of an A₂ photoactive monomer [bis(4‐hydroxybenzylidene)‐4‐phenyl cyclohexanone] and a B₃ monomer (1,3,5‐benzene tricarboxylic acid chloride) by the solution polycondensation method in the presence of pyridine as a condensing agent. PAHBP was thoroughly characterized by Fourier transform infrared, ¹H and ¹³C NMR, ultraviolet–visible spectrometry, and gel permeation chromatography. The inherent viscosity of the polymer was 0.35 dL/g in tetrahydrofuran. The degree of branching was 0.53, which confirmed the branched architecture of the polymer. Furthermore, thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy were used to examine the thermal stability and thermotropic liquid‐crystalline properties of the hyperbranched polyester. The polymer exhibited a nematic mesophase over a wide range of temperatures. The photoreactivity of PAHBP was studied by photolysis under ultraviolet light. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 53–61, 2006     

Hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s: Synthesis,characterization, end‐group modification,and optical properties

Novel AB₂‐type monomers such as 3,5‐bis(4‐methylolphenoxy)benzoic acid ( monomer 1 ), methyl 3,5‐bis(4‐methylolphenoxy) benzoate ( monomer 2 ), and 3,5‐bis(4‐methylolphenoxy)benzoyl chloride ( monomer 3 ) were synthesized. Solution polymerization and melt self‐polycondensation of these monomers yielded hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s. The structure of these polymers was established using FTIR and ¹H NMR spectroscopy. The molecular weights (M_w) of the polymers were found to vary from 2.0 × 10³ to 1.49 × 10⁴ depending on the polymerization techniques and the experimental conditions used. Suitable model compounds that mimic exactly the dendritic, linear, and terminal units present in the hyperbranched polymer were synthesized for the calculation of degree of branching (DB) and the values ranged from 52 to 93%. The thermal stability of the polymers was evaluated by thermogravimetric analysis, which showed no virtual weight loss up to 200 °C. The inherent viscosities of the polymers in DMF ranged from 0.010 to 0.120 dL/g. End‐group modification of the hyperbranched polymer was carried out with phenyl isocyanate, 4‐(decyloxy)benzoic acid and methyl red dye. The end‐capping groups were found to change the thermal properties of the polymers such as T_g. The optical properties of hyperbranched polymer and the dye‐capped hyperbranched polymer were investigated using ultraviolet‐absorption and fluorescence spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5414–5430, 2008     

One‐ and two‐dimensional NMR characterization of N‐vinyl‐2‐pyrrolidone/methyl acrylate copolymers

N‐vinyl‐2‐pyrrolidone/methyl acrylate (V/M) copolymers were prepared by free‐radical bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition of these copolymers was calculated from ¹H NMR spectra. The radical reactivity ratios for N‐vinyl‐2‐pyrrolidone (V) and methyl acrylate (M) were r_V = 0.09, r_M = 0.44. These reactivity ratios for the copolymerization of V and M were determined using the Kelen–Tudos and nonlinear least‐squares error‐in‐variable methods. The ¹³C{¹H} and ¹H NMR spectra of these copolymers overlapped and were complex. The complete spectral assignment of the ¹³C and ¹H NMR spectra were done with distortionless enhancement by polarization transfer and two dimensional ¹³C‐¹H heteronuclear single quantum correlation spectroscopic experiments. The two‐dimensional ¹H‐¹H homonuclear total correlation spectroscopic NMR spectrum showed the various bond interactions, thus inferring the possible structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2225–2236, 2002     

One‐ and two‐dimensional NMR characterization of N‐vinyl‐2‐pyrrolidone/methyl acrylate copolymers

N‐vinyl‐2‐pyrrolidone/methyl acrylate (V/M) copolymers were prepared by free‐radical bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition of these copolymers was calculated from ¹H NMR spectra. The radical reactivity ratios for N‐vinyl‐2‐pyrrolidone (V) and methyl acrylate (M) were r_V = 0.09, r_M = 0.44. These reactivity ratios for the copolymerization of V and M were determined using the Kelen–Tudos and nonlinear least‐squares error‐in‐variable methods. The ¹³C{¹H} and ¹H NMR spectra of these copolymers overlapped and were complex. The complete spectral assignment of the ¹³C and ¹H NMR spectra were done with distortionless enhancement by polarization transfer and two dimensional ¹³C‐¹H heteronuclear single quantum correlation spectroscopic experiments. The two‐dimensional ¹H‐¹H homonuclear total correlation spectroscopic NMR spectrum showed the various bond interactions, thus inferring the possible structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2225–2236, 2002     

Photoswitchable architectural polymer: Toward azo‐based polyamidoamine side‐chain dendritic polyester

A versatile approach to the synthesis of novel polyamidoamine (PAMAM) side‐chain dendritic polyester (SCDPE) possessing azobenzene motifs in the polymeric core is described and displayed reversible cis–trans (E/Z) isomerization upon exposure to UV light. A polymerization reaction was conducted in solution using ester‐terminated PAMAM dendritic diol ( 1a , G 3.5) and azobenzene dicarboxylic acid chloride in the presence of triethylamine. PAMAM dendritic diol 1a as well as SCDPE ( 1 ) were thoroughly characterized by means of IR and NMR (¹H and ¹³C) spectroscopies. The intrinsic viscosity of 1 at 36 °C in CHCl₃ was found to be 0.38 dl/g. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4182–4188, 2001     

Synthesis of a novel one‐pot approach of hyperbranched polyurethanes and their properties

A new method for the synthesis of hyperbranched polymers involving the use of AB_x macromonomers containing linear units have been investigated. Two types of novel hyperbranched polyurethanes have been synthesized by a one‐pot approach. The structures of monomers and polymers were characterized by elemental analysis, ¹H NMR, ¹³C NMR, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The hyperbranched polymers have been proven to be extremely soluble in a wide range of solvents. Polymer electrolytes were prepared with hyperbranched polymer, linear polymer as the host, and lithium perchlorate (LiClO₄) as the ion source. Analysis of the isotherm conductivity dependence of the ion concentration indicated that these hyperbranched polymers could function as a “solvent” for the lithium salt. The conductivity increased with the increasing concentration of hyperbranched polymers in the host polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 344–350, 2002     

s‐Triazine‐based hyperbranched polyethers: Synthesis,characterization, and properties

A series of s‐triazine‐based hyperbranched polyethers (HBPE) have been synthesized to obtain thermostability but flexible polymers by an interfacial polycondensation of different diols as A₂ and cyanuric chloride as B₃ monomers using A₂ + B₃ approach in the presence of a phase transfer catalyst. The polymerization reaction parameters are optimized, and the results indicate that the optimum conditions for the interfacial polycondensation are a 2:3 mole ratio of cyanuric chloride to diol using butanediol, benzyldimethylhexadecyl ammonium chloride as the catalyst, dichloromethane as the organic solvent, and a three‐step procedure with keeping the reaction mixture at different low temperatures for 2h/2h/5h. Other techniques such as high‐temperature solution, one‐step polycondensation, and transesterification were also carried out to synthesize the HBPE but proved to be not suitable due to large number of side reactions. The synthesized polymers were characterized by FTIR, ¹H NMR, and ¹³C NMR spectroscopy, hydroxyl number determination, solution viscosity measurements, and GPC analysis. The thermal behavior of the hyperbranched polymer was investigated by thermogravimetric analysis and differential scanning calorimetry. All the results were compared with those from an analogous linear polyether, obtained from 2‐methoxy‐4,6‐dichloro‐s‐triazine and butanediol by using the same polymerization technique. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3994–4004, 2010     

Cyclodextrin‐overhanging hyperbranched core‐double‐shell miktoarm architectures: Synthesis and gradient stimuli‐responsive properties

We report the synthesis and gradient stimuli‐responsive properties of cyclodextrin‐overhanging hyperbranched core‐double‐shell miktoarm architectures. A ionic hyperbranched poly(β‐cyclodextrin) (β‐CD) core was firstly synthesized via a convenient “A₂+B₃” approach. Double‐layered shell architectures, composed of poly(N‐isopropyl acrylamide) (PNIPAm) and poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) miktoarms as the outermost shell linked to poly(N,N‐diethylaminoethyl methacrylate) (PDEAEMA) homoarms which form the inner shell, were obtained by a sequential atom transfer radical polymerization (ATRP) and parallel click chemistry from the modified hyperbranched poly(β‐CD) macroinitiator. The combined characterization by ¹H NMR, ¹³C NMR, ¹H‐²⁹Si heteronuclear multiple‐bond correlation (HMBC), FTIR and size exclusion chromatography/multiangle laser light scattering (SEC/MALLS) confirms the remarkable hyperbranched poly(β‐CD) core and double‐shell miktoarm architectures. The gradient triple‐stimuli‐responsive properties of hyperbranched core‐double‐shell miktoarm architectures and the corresponding mechanisms were investigated by UV–vis spectrophotometer and dynamic light scattering (DLS). Results show that this polymer possesses three‐stage phase transition behaviors. The first‐stage phase transition comes from the deprotonation of PDEAEMA segments at pH 9–10 aqueous solution under room temperature. The confined coil‐globule conformation transition of PNIPAm and PDMAEMA arms gives rise to the second‐stage hysteretic cophase transition between 38 and 44 °C at pH 10. The third‐stage phase transition occurs above 44 °C at pH = 10 attributed to the confined secondary conformation transition of partial PDMAEMA segments. This cyclodextrin‐overhanging hyperbranched core‐double‐shell miktoarm architectures are expected to solve the problems of inadequate functionalities from core layer and lacking multiresponsiveness for shell layers existing in the dendritic core‐multishell architectures. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and application as polymer electrolyte of hyperbranched polyether made by cationic ring‐opening polymerization of 3‐{2‐[2‐(2‐hydroxyethoxy)ethoxy]ethoxymethyl}‐3′‐methyl‐oxetane

A novel cyclic ether monomer 3‐{2‐[2‐(2‐hydroxyethoxy)ethoxy]ethoxy‐methyl}‐3′‐methyloxetane (HEMO) was prepared from the reaction of 3‐hydroxymethyl‐3′‐methyloxetane tosylate with triethylene glycol. The corresponding hyperbranched polyether (PHEMO) was synthesized using BF₃·Et₂O as initiator through cationic ring‐opening polymerization. The evidence from ¹H and ¹³C NMR analyses revealed that the hyperbranched structure is constructed by the competition between two chain propagation mechanisms, i.e. active chain end and activated monomer mechanism. The terminal structure of PHEMO with a cyclic fragment was definitely detected by MALDI‐TOF measurement. A DSC test implied that the resulting polyether has excellent segment motion performance potentially beneficial for the ion transport of polymer electrolytes. Moreover, a TGA assay showed that this hyperbranched polymer possesses high thermostability as compared to its liquid counterpart. The ion conductivity was measured to reach 5.6 × 10^?5 S/cm at room temperature and 6.3 × 10^?4 S/cm at 80 °C after doped with LiTFSI at a ratio of Li:O = 0.05, presenting the promise to meet the practical requirement of lithium ion batteries for polymer electrolytes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3650–3665, 2006     

Studies on the phase structure of ethylene‐vinyl acetate copolymers by solid‐state 1H and 13C NMR

The phase structure of a series of ethylene‐vinyl acetate copolymers has been investigated by solid‐state wide‐line ¹H NMR and solid‐state high‐resolution ¹³C NMR spectroscopy. Not only the degree of crystallinity but the relative contents of the monoclinic and orthorhombic crystals within the crystalline region varied with the vinyl acetate (VA) content. Biexponential ¹³C NMR spin–lattice relaxation behavior was observed for the crystalline region of all samples. The component with longer ¹³C NMR spin–lattice relaxation time (T₁) was attributed to the internal part of the crystalline region, whereas the component with shorter ¹³C NMR T₁ to the mobile crystalline component was located between the noncrystalline region and the internal part of the crystalline region. The content of the mobile crystalline component relative to the internal part of the crystalline region increased with the VA content, showing that the ¹³C NMR spin–lattice relaxation behavior is closely related to the crystalline structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2199–2207, 2002     

Synthesis of novel hyperbranched polymers featuring oxazoline linear units and their application in fast‐drying solvent‐borne coating formulations

Novel acid‐terminated hyperbranched polymers (HBPs) containing adipic acid and oxazoline monomers derived from oleic and linoleic acid have been synthesized via a bulk polymerization procedure. Branching was achieved as a consequence of an acid‐catalyzed opening of the oxazoline ring to produce a trifunctional monomer in situ which delivered branching levels of >45% as determined by ¹H and ¹³C NMR spectroscopy. The HBPs were soluble in common solvents, such as CHCl₃, acetone, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide and were further functionalized by addition of citronellol to afford white‐spirit soluble materials that could be used in coating formulations. During end group modification, a reduction in branching levels of the HBPs (down to 12–24%) was observed, predominantly on account of oxazoline ring reformation and trans‐esterification processes under the reaction conditions used. In comparison to commercial alkyd resin paint coatings, formulations of the citronellol‐functionalized hyperbranched materials blended with a commercial alkyd resin exhibited dramatic decreases of the blend viscosity when the HBP content was increased. The curing characteristics of the HBP/alkyd blend formulations were studied by dynamic mechanical analysis which revealed that the new coatings cured more quickly and produced tougher materials than otherwise identical coatings prepared from only the commercial alkyd resins. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3964–3974     

Synthesis and characterization of N‐substituted hyperbranched polyureas

N,N′‐disubstituted hyperbranched polyureas with methyl, benzyl, and allyl substitutents were synthesized starting from AB₂ monomers based on 3,5‐diamino benzoic acid. Carbonyl azide approach, which generates isocyanate group in situ on thermal decomposition, was used for the protection of isocyanate functional groups. The N‐substituted hyperbranched polymers can be considered as the new class of internally functionalized hyperbranched polyureas wherein the substituent can function either as receptor or as a chemical entity for selective transformations as a tool to tailor the properties. The chain‐ends were also modified by attaching long chain aliphatic groups to fully realize the interior functionalization. This approach opens up a possible synthetic route wherein different functional substituents can be used to generate a library of internally functionalized hyperbranched polymers. All the hyperbranched polyureas were characterized by FTIR, ¹H‐NMR, DSC, TGA, and size exclusion chromatography. Degree of branching in these N,N′‐disubstituted hyperbranched polyureas, as calculated by ¹H‐NMR spectroscopy using model compounds, was found to be lower than the unsubstituted hyperbranched polyurea and is attributed to the lower reactivity of N‐substituted amines compared to that of unsubstituted amines. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5134–5145, 2004     

One‐pot synthesis and characterization of hyperbranched poly(ester‐amide)s from commercially available dicarboxylic acids and multihydroxyl secondary amines

A convenient and cost‐effective strategy for synthesis of hyperbranched poly(ester‐amide)s from commercially available dicarboxylic acids (A₂) and multihydroxyl secondary amine (CB₂) has been developed. By optimizing the conditions of model reactions, the AB₂‐type intermediates were formed dominantly during the initial reaction stage. Without any purification, the AB₂ intermediate was subjected to thermal polycondensation in the absence of any catalyst to prepare the aliphatic and semiaromatic hyperbranched poly(ester‐amide)s bearing multi‐hydroxyl end‐groups. The FTIR and ¹H NMR spectra indicated that the polymerization proceeded in the proposed way. The DBs of the resulting polymers were confirmed by a combination of inverse‐gated decoupling ¹³C NMR, and DEPT‐135 NMR techniques. The DBs of the hyperbranched poly(ester‐amide)s were in the range of 0.44–0.73, depending on the structure of the monomers used. The hyperbranched polymers exhibited moderate molecular weights with relatively broad distributions determined by SEC. All the polymers displayed low inherent viscosity (0.11–0.25 dL/g) due to the branched nature. Structural and end‐group effects on the thermal properties of the hyperbranched polymers were investigated using DSC. The thermogravimetric analysis revealed that the resulting polymers exhibit reasonable thermal stability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5077–5092, 2008     

Rare‐earth‐catalyzed alternating copolymerization of carbon monoxide with styrene

Rare‐earth acetates were used to catalyze the copolymerization reaction of carbon monoxide and styrene. Cupric acetate, 1,10‐phenanthroline, p‐toluenesulfonic acid, and 1,4‐benzoquinone were also added to the catalyst system. The structures of the copolymers obtained were characterized with IR, ¹H NMR, ¹³C NMR, wide‐angle X‐ray diffraction, and elemental analysis methods. The relationship between the catalytic activity and the catalyst composition was studied in detail. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 642–649, 2002; DOI 10.1002/pola.10147     

Synthesis of amphiphilic linear‐hyperbranched graft‐copolymers via grafting based on linear polyethylene backbone

The synthesis of amphiphilic linear‐hyperbranched graft‐copolymers in a grafting‐from approach is reported. The linear polyethylene with terminated hydroxyls, prepared by copolymerization of ethylene and 10‐undecen‐1‐ol, was used as macroinitiator for ring‐opening multibranching polymerization of glycidol by a typical slow monomer addition approach. Successful attachment of the hyperbranched grafts to the linear polyethylene backbone was confirmed by ¹H/¹³C NMR, GPC, and TGA. The degree of polymerization and M_w/M_n of hyperbranched grafts were efficiently controlled by temperature, deprotonation ratio as well as the molar ratio of glycidol/hydroxyl (N_glycidol/N_OH). The complicated microstructures caused by unsymmetric glycidol structure were analyzed by DEPT and 2D HSQC spectra, the degree of branching of 0.63–0.66 were calculated, indicating the extent of branch is close to theoretical values. The thermal analysis of linear‐hyperbranched copolymers via TGA and DSC is also presented. To our knowledge, this is the first report of a linear‐hyperbranched graft‐copolymer with a crystalline and nonpolar linear‐polyethylene segment. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2146–2154     

Easy synthesis and ring‐opening polymerization of 5‐Z‐amino‐δ‐valerolactone: New degradable amino‐functionalized (Co)polyesters

Novel 5‐Z‐amino‐δ‐valerolactone (5‐NHZ‐VL) was synthesized with an aim to prepare degradable polyesters and copolyesters having amino pendant groups. Following a straightforward and efficient synthetic pathway, 5‐NHZ‐VL was obtained in only two steps and up to 50% yield. The monomer was fully characterized by ¹H NMR, ¹³C NMR, ESI mass spectrometry, and HPLC. Various conventional conditions were tested for this lactone ring‐opening polymerization and led to the novel corresponding poly(5‐NHZ‐VL) (M_n = 7000 g/mol; PD = 1.2). Following this homopolymerization, 5‐NHZ‐VL was copolymerized with ε‐caprolactone to generate a family of copolyesters with an amino‐group content ranging from 10 to 80%. Finally, the polyelectrolyte poly(5‐NH₃⁺‐VL) was recovered by removal of the protecting group under acidic conditions, and integrity of the polyester backbone was confirmed by ¹H NMR. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

One‐step synthesis of hyperbranched polyethylene macroinitiator and its block copolymers with methyl methacrylate or styrene via ATRP

Block copolymers of hyperbranched polyethylene (PE) and linear polystyrene (PS) or poly(methyl methacrylate) (PMMA) were synthesized via atom transfer radical polymerization (ATRP) with hyperbranched PE macroinitiators. The PE macroinitiators were synthesized through a “living” polymerization of ethylene catalyzed with a Pd‐diimine catalyst and end‐capped with 4‐chloromethyl styrene as a chain quenching agent in one step. The macroinitiator and block copolymer samples were characterized by gel permeation chromatography, ¹H and ¹³C NMR, and differential scanning calorimetry. The hyperbranched PE chains had narrow molecular weight distribution and contained a single terminal benzyl chloride per chain. Both hyperbranched PE and linear PS or PMMA blocks had well‐controlled molecular weights. Slow initiation was observed in ATRP because of steric effect of hyperbranched structures, resulting in slightly broad polydispersity index in the block copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3024–3032, 2010     

Star polystyrene‐b‐hyperbranched polyglycidol: Synthesis and ionic conductivity

In this work, novel star‐hyperbranched block copolymers containing four polystyrene arms and hyperbranched polyglycidol at the end of each arm (sPS‐b‐HPG) have been synthesized. The polystyrene arms were prepared through atom transfer radical polymerization of styrene starting from a four‐arm initiator. The hydroxyl‐terminated PS star polymers served as precursors for the cationic ring‐opening polymerization of glycidol using BF₃·OEt₂ as the catalyst. The chemical structures of these block copolymers were characterized by using ¹H and ¹³C NMR. DSC analysis indicated that the star‐hyperbranched block copolymers exhibited two distinct glass transition temperatures corresponding to the linear PS and the HPG segments, respectively. The addition of LiClO₄ increased the T_g of HPG segments at low concentrations, however, decreased the T_g at high concentrations. The T_g of PS segments was not affected by the addition of salts at all. Furthermore, the interaction of sPS‐b‐HPG with LiBr was studied by using viscosity analysis based on the Jones–Dole equation. The star‐like PS core strengthened the interaction of sPS‐b‐HPG with Li ions that could facile the inhomogeneous distribution of Li cations and anions in different phases, which is important in polymeric electrolytes for lithium chemical power sources. The ionic conductivity of one sPS‐b‐HPG/LiClO₄ electrolyte was measured to be higher than that of HPG/LiClO₄ electrolyte. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 949–958, 2009     

Synthesis and micellization of star‐like hyperbranched polymer with poly(ethylene oxide) and poly(ε‐caprolactone) arms

Novel star‐like hyperbranched polymers with amphiphilic arms were synthesized via three steps. Hyperbranched poly(amido amine)s containing secondary amine and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3‐amino‐1,2‐propanediol (APD) with feed molar ratio of 1:2. ¹H, ¹³C, and HSQC NMR techniques were used to clarify polymerization mechanism and the structures of the resultant hyperbranched polymers. Methoxyl poly(ethylene oxide) acrylate (A‐MPEO) and carboxylic acid‐terminated poly(ε‐caprolactone) (PCL) were sequentially reacted with secondary amine and hydroxyl group, and the core–shell structures with poly(1TT‐2APD) as core and two distinguishing polymer chains, PEO and PCL, as shell were constructed. The star‐like hyperbranched polymers have different sizes in dimethyl sulfonate, chloroform, and deionized water, which were characterized by DLS and ¹H NMR. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1388–1401, 2008     

Synthesis and characterization of hyperbranched‐poly(siloxysilane)‐based polymeric photoinitiators

Three UV‐sensitive, hyperbranched‐poly(siloxysilane)‐based polymeric photoinitiators, bearing an alkyl phenone moiety linked to the surface of the hyperbranched polymer, were synthesized via the hydrosilylation of hyperbranched poly(siloxysilane) and modified UV‐sensitive compounds. Hyperbranched poly(siloxysilane) was prepared via the polyhydrosilylation of the AB₂‐type monomer methylvinyldichlorosilane. The chemical structures of the polymeric photoinitiators were characterized with ¹H, ¹³C, and ²⁹Si NMR, elemental analysis, Fourier transform infrared, differential scanning calorimetry, UV spectrophotometry, and thermogravimetric analysis. The UV‐curing behaviors of the blends of the hyperbranched polymeric photoinitiators with UV‐curable epoxy acrylate (EA) resin were determined by Fourier transform infrared, and the results showed that the initiation efficiency of the polymeric photoinitiators was excellent and that the thermostability of the EA/polymeric photoinitiator curing systems was higher than that of the EA/photoinitiators. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3261–3270, 2006