Phase separation in random copolymers from high conversion free radical copolymerization, 3

Braun, Dietrich; Meyer, Manuela Iris

doi:10.1002/(sici)1522-9505(19991101)271:1<68::aid-apmc68>3.0.co;2-q

Cited by 3 publications

(2 citation statements)

References 4 publications

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“…Typically, the conversion heterogeneity should be low for most applications, because it offers better application properties. In extreme cases conversion heterogeneity can influence phase separation that can cause deterioration of polymer product properties and even polymer blend formation . However, there are certain exceptions.…”

Section: Resultsmentioning

confidence: 99%

Reactivity ratios and copolymer properties of 2‐(diisopropylamino)ethyl methacrylate with methyl methacrylate and styrene

Faraguna

Vidović

Jukić

2015

Polymer International

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Free radical copolymerization kinetics of 2-(diisopropylamino)ethyl methacrylate (DPA) with styrene (ST) or methyl methacrylate (MMA) was investigated and the corresponding copolymers obtained were characterized. Polymerization was performed using tert-butylperoxy-2-ethylhexanoate (0.01 mol dm −3 ) as initiator, isothermally (70 ∘ C) to low conversions (<10 wt%) in a wide range of copolymer compositions (10 mol% steps). The reactivity ratios of the monomers were calculated using linear Kelen-Tüdős (KT) and nonlinear Tidwell-Mortimer (TM) methods. The reactivity ratios for MMA/DPA were found to be r 1 = 0.99 and r 2 = 1.00 (KT), r 1 = 0.99 and r 2 = 1.03 (TM); for the ST/DPA system r 1 = 2.74, r 2 = 0.54 (KT) and r 1 = 2.48, r 2 = 0.49 (TM). It can be concluded that copolymerization of MMA with DPA is ideal while copolymerization of ST with DPA has a small but noticeable tendency for block copolymer building. The probabilities for formations of dyad and triad monomer sequences dependent on monomer compositions were calculated from the obtained reactivity ratios. The molar mass distribution, thermal stability and glass transition temperatures of synthesized copolymers were determined. Hydrophobicity of copolymers depending on the composition was determined using contact angle measurements, decreasing from hydrophobic polystyrene and poly(methyl methacrylate) to hydrophilic DPA. Copolymerization reactivity ratios are crucial for the control of copolymer structural properties and conversion heterogeneity that greatly influence the applications of copolymers as rheology modifiers of lubricating oils or in drug delivery systems.

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Section: Resultsmentioning

confidence: 99%

Reactivity ratios and copolymer properties of 2‐(diisopropylamino)ethyl methacrylate with methyl methacrylate and styrene

Faraguna

Vidović

Jukić

2015

Polymer International

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“…The addition of the mono-vinyl decreases the viscosity as well as the conversion-dependent physical limitations to diffusion of immiscible phases during polymerization. This is different from other approaches that utilize the polymerization of comonomers to create limited miscibility during the reaction to promote PIPS[13, 14, 31], as we use the presence of a comonomer to increase the time between phase separation and gelation, but to the extent possible, not to alter miscibility. This permits a broader range of phase morphologies and processing conditions that can be utilized to form cross-linked, phase-separated networks.…”

Section: Introductionmentioning

confidence: 99%

Accessing photo-based morphological control in phase-separated, cross-linked networks through delayed gelation

Szczepanski

Stansbury

2015

European Polymer Journal

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This work presents an approach to extend the period for phase separation, independent of temperature, in ambient phase-separating photopolymerizations based on the copolymerization of structurally similar mono- and di-vinyl monomers. Copolymer resins composed of triethylene glycol dimethacrylate (TEGDMA) and ethylene glycol methyl ether methacrylate (EGMEMA) were modified with a thermoplastic prepolymer, poly(butyl methacrylate). With increasing EGMEMA modification into the bulk TEGDMA resin, there is a decrease in the initial reaction rate, which increases the time for development of compositionally different phases prior to network gelation. The period between phase separation and gelation was probed through optical and rheological measurements, and it was extended from 22 s in a TEGDMA resin to 69 s in a TEGDMA:EGMEMA copolymer, allowing these materials to be processed under a wide range of UV-irradiation intensities (300 µW cm−2 – 100 mW cm−2), which provided an additional degree of control over the resulting phase separated domain size and morphology.

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Gradient copolymers with broad glass transition temperature regions: Design of purely interphase compositions for damping applications

Mok

Kim

Torkelson

2007

J Polym Sci B Polym Phys

122

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Gradient copolymers with gradients in composition along the chain lengths are synthesized by controlled radical polymerization, and their damping behaviors are compared to those of random and block copolymers. The effect of comonomer incompatibility is studied by comparing behaviors of strongly segregating styrene/4‐hydroxystyrene (S/HS) and moderately segregating styrene/n‐butyl acrylate (S/nBA) copolymers. The effect of composition gradient steepness is studied by designing “constant” or “increasing” gradients via the comonomer addition rate during semibatch polymerization. Dynamic mechanical analysis (DMA) is used to compare the temperature dependences of the storage modulus (E′), loss modulus (E″), and tan δ of the materials. A glass transition breadth (ΔTg) is defined by a temperature range over which E′ decreases from 109 Pa to 108 Pa. The gradient copolymer ΔTgs are at least four times larger than the random copolymer ΔTgs. The S/nBA gradient copolymers show strong effects of gradient steepness on ΔTg, with ΔTg being much larger for the increasing gradient than for the constant gradient. DMA data are compared to predictions by Hashimoto et al. for tapered block copolymers in the limit where the taper extends across the entire chain. The shapes of their calculated temperature dependences of E′ and E″ correspond well to the gradient copolymers with large ΔTg values, providing strong support for symmetric gradient copolymers forming nanoscale, ordered domains with sinusoidal composition profiles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 48–58, 2008

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Phase separation in random copolymers from high conversion free radical copolymerization, 3

Cited by 3 publications

References 4 publications

Reactivity ratios and copolymer properties of 2‐(diisopropylamino)ethyl methacrylate with methyl methacrylate and styrene

Reactivity ratios and copolymer properties of 2‐(diisopropylamino)ethyl methacrylate with methyl methacrylate and styrene

Accessing photo-based morphological control in phase-separated, cross-linked networks through delayed gelation

Gradient copolymers with broad glass transition temperature regions: Design of purely interphase compositions for damping applications

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