Synthesis of aromatic carboxyl functionalized polymers by atom transfer radical polymerization

The synthesis of aromatic carboxyl functionalized polymers by atom transfer radical polymerization is described. The α‐bromo‐p‐toluic acid ( 1 ) initiated polymerization of styrene in the presence of copper(I) bromide and 2,2′‐bipyridyl affords quantitative yields of the corresponding aromatic carboxyl functionalized polystyrene ( 2 ). Polymerization proceeded via a controlled free radical process to afford quantitative yields of the corresponding aromatic carboxyl functionalized polymers with predictable molecular weights (M_n = 1600–25 900 g mol⁻¹), narrow molecular weight distribution (M_w /M_n = 1.1–1.40) and an initiator efficiency above 0.87. The polymerization process was monitored by gas chromatographic analysis. The functionalized polymers were characterized by thin layer chromatography, size exclusion chromatography, spectroscopy, potentiometry and elemental analysis. © 2000 Society of Chemical Industry     

Synthesis and characterization of a novel highly phosphonated water-insoluble polymer

A novel polymer, functionalized by tetrafluoroaryl phosphonic acid units, was prepared by free-radical polymerization of the corresponding styrene monomer. The obtained polymer was analyzed by gel permeation chromatography, differential scanning calorimetry, and spectroscopy (NMR, IR). Ion exchange capacity of the water-insoluble polymer was determined in methanol solution by titration with 0.1M NaOH. The proton conductivity of the polymer of 9.91 × 10⁻⁷ S cm⁻¹ as disclosed by electrochemical impedance spectroscopy renders this polymer a promising candidate for solid electrolyte applications or as a water-insoluble dopant for proton exchange membrane applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48235.     

Controlling phosphonic acid substitution degree on proton conducting polyphosphazenes

This paper is to describe the development of a synthetic strategy for the preparation of phosphonic acid functionalized poly(aryloxyphosphazene) membranes with different substitution degree of phosphonic acid. Synthesized polymers have been characterized by standard spectroscopic techniques; FT-IR, ¹H, ³¹P and ¹⁹F NMR and element analysis. Proton conductivities of phosphonic acid substituted polymers have been investigated with impedance spectroscopy at different temperatures. Furthermore, the correlations of the proton conductivity and ion exchange capacity with the substitution degree of phosphonic acid have also been investigated. Thermal properties and water uptake properties of the polymers are also investigated. It is found that the proton conductivity and initial decomposition temperature of the polymers increases up to an appropriate amount of phosphonic acid substitution degree, which can be a useful PEM candidate for fuel cells.     

Phosphonic acid‐containing polysulfones as anticorrosive layers

As a part of research work to elaborate polymeric materials for metal corrosion protection, we have developed a new family of phosphonic acid‐containing polymers. The synthesis and the characterization of polysulfones bearing alkyl phosphonate ester side groups are first described. These polymers are synthesized by direct polycondensation of a phosphonate ester‐containing bisphenol by aromatic nucleophilic substitution. The physicochemical properties of the resulting polymers are described. Acidic hydrolysis of phosphonate esters results in the formation of phosphonic acid groups. A series of phosphonic acid‐containing polysulfones is therefore obtained and characterized. A preliminary evaluation of the anticorrosive properties of these polymers is described. In 0.25M Na₂SO₄ solution, the corrosion rate of a polymer‐coated mild steel sample is much lower than of the free metal substrate. These results suggest that phosphonic acid‐containing polysulfones might be interesting as anticorrosive coatings. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41890.     

Graft copolymerization of methyl acrylate onto sago starch using ceric ammonium nitrate as an initiator

The graft copolymerization of methyl acrylate onto sago starch was carried out by a free radical initiating process. The free radicals were produced by the chemical initiation method in which ceric ammonium nitrate was used as an initiator. It was found that the percentages of grafting, grafting efficiency, and rate of grafting were all dependent on the concentration of ceric ammonium nitrate (CAN), methyl acrylate (MA), sago starch (AGU), mineral acid (H₂SO₄), and reaction temperature and period. The variables affecting the graft copolymerization were thoroughly examined. The optimum yield of grafting was obtained when the concentration of CAN, MA, AGU, and H₂SO₄ were used at 8.77 × 10⁻³, 0.803, 0.135, and 0.175 mol L⁻¹, respectively. The optimum reaction temperature and period were 50°C and 60 min, respectively. The rate of graft polymerization was explored on the basis of experimental results and reaction mechanism. The evidence of grafted copolymers was investigated by using FTIR spectroscopy, TG, and DSC analysis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 516–523, 2000     

Kinetic Analysis of Terminal and Unactivated C?H Bond Oxyfunctionalization in Fatty Acid Methyl Esters by Monooxygenase‐Based Whole‐Cell Biocatalysis

The alkane monooxygenase AlkBGT from Pseudomonas putida GPo1 constitutes a versatile enzyme system for the ω‐oxyfunctionalization of medium chain‐length alkanes. In this study, recombinant Escherichia coli W3110 expressing alkBGT was investigated as whole‐cell catalyst for the regioselective biooxidation of fatty acid methyl esters to terminal alcohols. The ω‐functionalized products are of general economic interest, serving as building blocks for polymer synthesis. The whole‐cell catalysts proved to functionalize fatty acid methyl esters with a medium length alkyl chain specifically at the ω‐position. The highest specific hydroxylation activity of 104 U g_CDW⁻¹ was obtained with nonanoic acid methyl ester as substrate using resting cells of E. coli W3110 (pBT10). In an optimized set‐up, maximal 9‐hydroxynonanoic acid methyl ester yields of 95% were achieved. For this specific substrate, apparent whole‐cell kinetic parameters were determined with a V_max of 204±9 U g_CDW⁻¹, a substrate uptake constant (K_S) of 142±17 μM, and a specificity constant V_max/K_S of 1.4 U g_CDW⁻¹ μM ⁻¹ for the formation of the terminal alcohol. The same E. coli strain carrying additional alk genes showed a different substrate selectivity. A comparison of biocatalysis with whole cells and enriched enzyme preparations showed that both substrate availability and enzyme specificity control the efficiency of the whole‐cell bioconversion of the longer and more hydrophobic substrate dodecanoic acid methyl ester. The efficient coupling of redox cofactor oxidation and product formation, as determined in vitro, combined with the high in vivo activities make E. coli W3110 (pBT10) a promising biocatalyst for the preparative synthesis of terminally functionalized fatty acid methyl esters.     

UV-light assisted single step route to functional PEEK surfaces

Polyether ether ketone (PEEK) is a thermoplastic polymer of high technological relevance and is composed of repeating phenyl ether and benzophenone units. In the present work we will demonstrate the potential of UV irradiation assisted generation of free radicals on the surface benzophenone units to graft a variety of polymer chains on the PEEK surface. Both “grafting-to” and “grafting-from” approaches were explored by using different monomers and polymers. Styrene, butyl acrylate (BA), vinyl phosphonic acid (VPA), acrylic acid (AA), polyacrylic acid (PAA) and monomethoxy terminated oligo (ethylene glycol) methacrylate (MeOEGMA) were successfully utilized for this purpose. The functionalized membranes were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier-transformed Infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and contact angle (CA) goniometry. PAA and PVPA functionalized PEEK surfaces exhibited pH responsive wettability behavior. PAA functionalized PEEK surfaces were further modified with lysine, which led to the controlled surface wettability over a broader pH range as compared to the simple PAA functionalized surface. The grafting with polyMeOEGMA rendered PEEK surface with nonfouling properties against bacterial growth. Employing this highly economical and simple method, the surface properties of PEEK can be modulated and tuned according to a specific application.     

Styrene/phosphonic acid copolymers: Synthesis and thermal,mechanical, and electrochemical characterization

In this study, a series of poly(styrene‐co‐vinyl phosphonic acid) [P(S‐co‐VPA)] copolymers were synthesized by the free‐radical copolymerization of styrene and vinyl dimethyl phosphonate followed by alkaline hydrolysis. The P(S‐co‐VPA) copolymers were characterized by size exclusion chromatography (gel permeation chromatography), Fourier transform infrared vibrational spectroscopy, proton nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and electrochemical impedance spectroscopy. Despite the difference between the copolymerization ratios of styrene and vinyl dimethyl phosphonate, the resulting copolymers presented single glass transitions at temperatures that depended on the acidic group amount. The glass transition shifted to a higher temperature and became broader as the amount of phosphonic acid increased. The storage modulus at temperatures higher than the glass transition also increased with increasing acidic groups because of intramolecular and intermolecular interactions. All of the acid copolymers were thermally stable to at least 300°C. A high oxidative stability was found for 3 : 1 P(S‐co‐VPA), which also presented conductivity values on the order of 10⁻⁶ Ω⁻¹ cm⁻¹ at room temperature. The 1 : 1 P(S‐co‐VPA) membrane presented Arrhenius‐type behavior at temperatures from 30 to 80°C and conductivity on the order of 10⁻⁵ Ω⁻¹ cm⁻¹. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Boric acid binding studies with diol containing polyethylenimines as determined by 11B NMR spectroscopy

Three water‐soluble polymers incorporating increasing levels of 2,3‐dihydroxy propyl attached to polyethylenimine (PEI) backbone were synthesized, characterized by NMR, and investigated for their ability to bind boric acid (BA). ¹¹B NMR spectroscopy showed that BA interacted with the polymeric 2,3‐dihydroxy propyls by forming borate monoester and borate diesters in the boron concentration range of 100–1000 ppm and at 0.0775M polymer. Borate monoester species predominated for low functionalization levels (33% of the PEI amines functionalized), whereas borate diester species dominated for the higher functionalized polymers (66–100% of the PEI amines functionalized). All three polymers showed that 100% of the BA was bound as a mixture of borate mono‐ and diesters at 100‐ppm boron. The overall best performer based on total borate ester formation was the 2/3‐PEI, with a binding K_d of 631 at 200 ppm boron. Borate ion concentration was measured from the ¹¹B NMR chemical shift of the BA/borate peak and it decreased as 1/3‐PEI > 2/3‐PEI > 3/3‐PEI. Variable temperature ¹¹B NMR showed drastic reduction of borate ester species at 65°C. Thus, PEI polymers, as the ones investigated in this work, are reasonable candidates for the selective recovery and recycle of BA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4411–4418, 2006     

Synthesis and characterization of boron-acrylate/Santa Barbara Amorphous-15 polymer composite

In the present work, boron-acrylate/Santa Barbara Amorphous (SBA)-15 polymer composite was synthesized using free radical polymerization method. Firstly, SBA-15 was functionalized with 3-(trimethoxysilyl)propyl methacrylate to obtain chemically bonded boron acrylate (BAc) polymer on the SBA-15 surface. The structural analysis was evaluated via Fourier-transform infrared spectroscopy and solid-state nuclear magnetic resonance ¹³C. Samples were also characterized by using scanning electron microscopy, X-ray powder diffraction, N₂ adsorption/desorption and thermogravimetric analysis. In order to examine the BAc polymers in the mesopores, the silica framework was removed via hydrofluoric acid etching process. The results indicated that the synthesis of boron-acrylate/SBA-15 polymer composite was performed successfully. Thermal stabilities of the composites were higher with greater amounts of BAc polymer in mesopores under oxidative conditions.     

Ring opening reactions of glycidyl methacrylate copolymers to introduce bulky organosilicon side chain substituents

Summary Glycidyl methacrylate (GMA) random copolymers with methyl acrylate (MA), ethyl acrylate (EA), n-butyl acrylate (BA), methyl methacrylate (MMA), ethyl methacrylate (EMA) and n-butyl methacrylate (BMA) were synthesized by solution free radical polymerizations, at 70±1 °C using α,α’-azobis(isobutyronitrile) as an initiator to give the copolymers I – VI in good yields. The copolymer compositions were obtained using related ¹H NMR spectra and the polydispersity indices of the copolymers determined using gel permeation chromatography (GPC). Tris(trimethylsilyl)methyl (Tsi=trisyl) groups were then covalently attached to the obtained copolymers as side chains by ring opening reaction between excess of TsiLi and expoxide groups of GMA units to give the copolymers I_Tsi – VI_Tsi in good yields. In the coupling reaction, the TsiLi reacted selectively with the epoxy groups of the backbone polymer rather than with the carbonyl groups of the backbone. This method of preparing functionalized silanes is limited by the readiness with which TsiLi abstracts a proton, if one is available, rather than attacks at carbon. In addition in the reaction with epoxides, the product alkoxide can transfer a silyl group from carbon to oxygen or ring opening polymerization. However these were shown not to occur at the conditions of interest here. The epoxy group possesses a higher reactivity for the TsiLi than the ester and chloromethyl groups. The ring opening reaction between the epoxy group and the TsiLi is simple and fast. All the resulted polymers were characterized by FT-IR and ¹H NMR spectroscopic techniques. The glass transition temperature (Tg) of all copolymers was determined by differential scanning calorimetry (DSC) apparatus. All the polymers containing trisyl groups showed a high glass transition temperature in comparison with unmodified copolymers (I – VI). Attaching the tris(trimethylsilyl)methyl group to macromolecular chain should lead to important modifications of polymer properties such as gas permeability and perm selectivity parameters.     

Synthesis and characterization of poly(hydroxamic acid) chelating resin from poly(methyl acrylate)‐grafted sago starch

A new chelating ion‐exchange resin containing the hydroxamic acid functional group was synthesized from poly(methyl acrylate) (PMA)‐grafted sago starch. The PMA grafted copolymer was obtained by a free‐radical initiating process in which ceric ammonium nitrate was used as an initiator. Conversion of the ester groups of the PMA‐grafted copolymer into hydroxamic acid was carried out by treatment of an ester with hydroxylamine in an alkaline solution. The characterization of the poly(hydroxamic acid) chelating resin was performed by FTIR spectroscopy, TG, and DSC analyses. The hydroxamic acid functional group was identified by infrared spectroscopy. The chelating behavior of the prepared resin toward some metal ions was investigated using a batch technique. The binding capacities of copper, iron, chromium, and nickel were excellent and the copper capacity was maximum (3.46 mmol g⁻¹) at pH 6. The rate of exchange of the copper ion was very fast that is, t_1/2 < 5 min. It was also observed that the metal ion‐sorption capacities of the resin were pH‐dependent and its selectivity toward the metal ions used is in the following order: Cu²⁺ > Fe³⁺ > Cr³⁺ > Ni²⁺ > Co²⁺ > Zn²⁺ > Cd²⁺ > As³⁺ > Pb²⁺. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1256–1264, 2001     

In situ preparation of Au or Ag nanoparticles in the presence of hyperbranched poly(amidoamine)s with hydrophobic end‐groups as nanoreactors and reductants

Hyperbranched poly(amidoamine)s with methyl ester terminals (HPAMAM‐COOCH₃) were used as nanoreactors and reductants to prepare gold or silver nanoparticles (Au NPs or Ag NPs). HPAMAM‐COOCH₃ could bind AuCl₄ ⁻ (or Ag⁺) and then reduce AuCl₄ ⁻ (or Ag⁺) into Au NPs (or Ag NPs) through their internal amines, while the external methyl ester groups prevented the aggregation of polymers. The formation of Au NPs or Ag NPs was verified using transmission electron microscopy (TEM), ultraviolet‐visible spectroscopy (UV‐Vis), X‐Ray powder diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), and thermogravimetric analysis (TGA), confirming the formation of Au NPs or Ag NPs with small particle size and low size distribution.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Organic acids catalyzed polymerization of ε‐caprolactone: Synthesis and characterization

Environmentally friendly organocatalytic synthesis of aliphatic polyesters was studied. The catalysis investigated is novel, and lends itself well to the potential production of valuable biodegradable products. The reactions were based on an organic acids‐catalyzed ring‐opening polymerization of ε‐caprolactone with fatty acid derivatives as the initiator and were performed in the absence of solvents. The chemical structures of the functionalized polymers were confirmed by ¹H and ¹³C‐NMR spectra. Polymers with different molecular weights, in the range 10,900–15,200 were obtained in the presence of fumaric acid as catalyst. The thermal properties of the functionalized PCLs were determined by modulated differential scanning calorimetry and thermogravimetric analysis. The MDSC results verified that the crystallinity and the melting point of the lipid‐functionalized polymers were lower than that of the unfunctionalized poly(ε‐caprolactone). The hydrolytic degradation of the functionalized polymer was also investigated. The result shows the degradation rate was affected by the presence of oleic acid derivatives in the polymer molecule. The lipid‐functionalized polymers synthesized by the metal‐free polymerization systems seem to be suitable biodegradable polyesters for use in biomedical and pharmacological applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Surface modification of bioceramics by grafting of tailored allyl phosphonic acid

Abstract

A new route to interfacial bonding between ceramic and matrix in biocomposites is identified. A tailored allyl phosphonic acid is used as a coupling agent bound to the surface of a bioceramic to form a 'grafted' calcium phosphate (CAP). The allyl phosphonic acid coupling agent is synthesised by reaction of allyl halide and trialkyl phosphite. Successful synthesis was confirmed by nuclear magnetic resonance and Fourier transform infrared spectroscopy (FTIR). The allyl phosphonic acid was incorporated onto calcium phosphate using a wet chemical coprecipitation synthesis route. The resulting 'grafted' CAP was characterised using FTIR coupled with photoacoustic sampling, and Fourier transform Raman spectroscopy (FTR). The spectroscopic data suggest an interaction between the allyl phosphonic acid and calcium phosphate resulting from observed reductions in intensity of the hydroxyl (3570 cm^?1) and phosphate ν ₃ (1030 cm^?1) peaks. The continued presence of C=C functionality on the surface of the grafted CAP was indicated by FTIR and FTR spectra (peaks at 1650 and 1635 cm^?1 respectively) and confirmed by X-ray photoelectron spectroscopy (XPS). On the basis of these results, it is concluded that grafted CAP may be used to produce a chemically bonded composite with superior mechanical properties.     

Synthesis and characterization of styrene–acrylic ester copolymers

Homopolymers and copolymers of styrene and different acrylic esters (i.e., acrylates) were synthesized by the free‐radical solution polymerization technique. Feed ratios of the monomers styrene and cyclohexyl acrylate/benzyl acrylate were 90 : 10, 75 : 25, 60 : 40, 50 : 50, 40 : 60 and 20 : 80 (v/v) in the synthesis of copolymers. All 6 homopolymerizations of acrylic ester synthesis were carried out in N,N(dimethyl formamide) except for the synthesis of poly(cyclohexyl acrylate) (PCA), where the medium was 1,4‐dioxane. Benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) were used as initiators. The polymers synthesized were characterized by FTIR, ¹H‐NMR, ¹³C‐NMR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and viscosity measurements. The reactivity ratios were determined by the Fineman–Ross method using ¹H‐NMR spectroscopic data. The reactivity ratios (r) for the copolymerization of styrene (r_S) with cyclohexyl acrylate (r_CA) were found to be r_S = 0.930 and r_CA = 0.771, while for the copolymerization of styrene with benzyl acrylate, the ratios were found to be r_S = 0.755 and r_BA = 0.104, respectively. The activation energies of decomposition (E_a) and glass‐transition temperature (T_g) for various homo‐ and copolymers were evaluated using TGA and DSC analysis. The activation parameters of the viscous flow, voluminosity (V_E) and shape factor (ν) were also computed for all systems using viscosity data. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1513–1524, 2001     

Methacrylate/acrylate terminated derivatives of diglycidyl hexahydrophthalate: Synthesis,structural, and thermal characterization

Mono‐ or di(meth)acrylate‐terminated derivatives of diglycidyl hexahydrophthalate (ER) were prepared by reacting 1 : 1 or 1 : 2M ratio of ER and methacrylic acid or acrylic acid. These vinyl ester (VE) resins were characterized by determining epoxy equivalent weight, acid number, and molecular weight by gel permeation chromatography. Structural characterization was done by FTIR and ¹H NMR spectroscopy. In the ¹H NMR spectra of acrylate‐terminated VE resins, three proton resonance signals were observed in the region 5.8–6.4 ppm due to vinyl group while in methacrylate‐terminated VE resins only two proton resonance signals due to vinylidene protons were observed at 5.6–6.1 ppm. The Brookfield viscosity (room temperature (25 ± 2)°C) of these resins diluted with varying amounts of MMA was determined at 20 rpm. Curing behavior was monitored by determination of gel time and differential scanning calorimetry. An exothermic transition was observed in the DSC scans in the temperature range of (81–150)°C. Isothermal curing of MMA‐diluted VE resins containing AIBN as an initiator was done at 60°C for 2 h in N₂ atmosphere, and then heating for another 2 h in static air atmosphere. Thermal stability of isothermally cured resins in N₂ atmosphere was evaluated by thermogravimetric analysis. All cured resins decomposed above 310°C in single step. Thermal stability of the cured resins having acrylate end caps was marginally higher than the resins having methacrylate end groups. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Synthesis and characterization of poly(hydroxamic acid)–poly(amidoxime) chelating ligands from polymer‐grafted acacia cellulose

Graft copolymerization of methyl acrylate (MA) and acrylonitrile (AN) onto acacia cellulose was carried out using free radical initiating process in which ceric ammonium nitrate (CAN) was used as an initiator. The optimum grafting yield was determined by the certain amount of acacia cellulose (AGU), mineral acid (H₂SO₄), CAN, MA, and AN at 0.062, 0.120, 0.016, 0.397, and 0.550 mol L^?1, respectively. The poly(methyl acrylate‐co‐acrylonitrile)‐grafted acacia cellulose was obtained at 55°C after 2‐h stirring, and purified acrylic polymer‐grafted cellulose was characterized by FTIR and TG analysis. Therein, the ester and nitrile functional groups of the grafted copolymers were reacted with hydroxylamine solution for conversion into the hydroxamic acid and amidoxime ligands. The chelating behavior of the prepared ligands toward some metal ions was investigated using batch technique. The metal ions sorption capacities of the ligands were pH dependent, and the sorption capacity toward the metal ions was in the following order: Zn²⁺ > Fe³⁺ > Cr³⁺ > Cu²⁺ > Ni²⁺. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of phosphonate and aromatic-based polynorbornene polymers derived from the ring opening metathesis polymerization method and investigation of their thermal properties

In the present study, phosphonate ester, phosphonic acid, and aromatic (phenyl, naphthalene, anthracene) groups containing polymers were synthesized by the ROMP method to analyze thermal properties of these polymers. Thermal stability of the synthesized polymers is tested by thermal gravimetric analysis under nitrogen, air, and microscale combustion calorimetry analysis. Analysis shows that thermal behavior is directly related to the phosphorus level in the copolymer series. All the polymers are thermally stable under nitrogen and air up to 900 °C. Synergistic charring effect under air was observed between aromatic groups and phosphonic acid functionality in the copolymer series. Anthracene units have a greater potential to form carbonaceous char than the naphthalene and phenyl units. Phosphonate ester and naphthalene units bearing copolymers (P3A) gave 8.13% char yield at 900 °C under air. Phosphonic acid derivatives of this polymer, P3D, gave a highest char residue of 17.15% under the same condition. The introduction of phosphonate and phosphonic acid in each copolymer series is also beneficial in reducing the peak heat release rate (PHRR). Cleavage of the phosphonate ester bearing homopolymer (P4) to phosphonic acid (P4A) causes a sharp decrease in the PHRR ratio from 274 to 28.2 W/g. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47085.     

Photolysis of poly(benzyl methacrylate)s and poly(benzyl acrylate)s in solution and films

Methacrylate and acrylate copolymers containing benzyl or 1‐phenylethyl groups and their monomeric model compounds were irradiated with a 254‐nm light in CH₂Cl₂ and solid films. Low molecular weight and polymeric products were analyzed by gas chromatography (GC) and NMR spectroscopy, respectively, and main‐chain scission efficiencies were determined by gel permeation chromatography (GPC). The results indicate that the ester bond cleavage in the side chain produces alkyl radicals in the main chain, leading to main‐chain scission and crosslinking. The higher stability of tertiary alkyl radicals formed in methacrylate polymers lead to the predominant main‐chain scission in solution. On the other hand, acrylate polymers were less susceptible to photodegradation. The degradabilities of the polymer films reflected those of the polymer solutions, although crosslinking preferentially occurred. The distinct effect of oxygen on the degradation was also observed in solution and films. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2227–2236, 2001