Oligomers for thermosetting compositions, cured compositions, and prepregs and laminates based on same

Abstract

This disclosure relates to oligomers and thermosetting compositions including the same suitable for use in making electronic materials such as circuit board substrates, as well as cured compositions, prepregs and laminates based on such thermosetting compositions. One aspect of the disclosure is a phenyl-substituted oligomer that is a reaction product of an oligomerization mixture comprising one or more of styrene and divinylbenzene; and one or more of isopropenylbenzene and diisopropenylbenzene, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues of at least 20%; and the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants of at least 50%.

Description

OLIGOMERS FOR THERMOSETTING COMPOSITIONS, CURED COMPOSITIONS, AND PREPREGS AND LAMINATES BASED ON SAMECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application no. 63 / 697,134, filed September 20, 2024, which is hereby incorporated herein by reference in its entirety.BACKGROUND OF THE DISCLOSURE1. Field of the Disclosure

[0002] This disclosure relates to thermosetting compositions suitable for use in making electronic materials such as circuit board substrates, as well as cured compositions, prepregs and laminates based on such thermosetting compositions.2. Technical Background

[0003] A variety of polymeric materials have been developed for use as substrates for electronics. To provide for desirably high transmission speeds, desirable properties include low dielectric constant and low dissipation factor, especially at high frequencies, as well as high glass transition temperature, low thermal expansion, and high temperature stability.

[0004] Such materials are often provided with a layer of copper foil laminated thereto. The peel strength between the copper foil and the polymeric material is an important property of such materials. During processing into devices these materials are subjected to high heat, e.g., through soldering, and insufficient adhesion between the copper and the polymer can cause in the device defects such as track lift, pad lift and large scale delamination. Adhesion is typically measured by the “peel strength,” which quantifies the amount of force needed to peel a copper layer away from the material.

[0005] But while peel strength is important, so are the electronic and thermal properties. What are needed are new materials that have not only high peel strength with copper, but also good dielectric properties, especially at high frequencies, and good thermal properties.SUMMARY OF THE DISCLOSURE

[0006] In one aspect, the disclosure provides an phenyl-substituted oligomer that is a reaction product of an oligomerization mixture comprising one or more of styrene and divinylbenzene; and one or more of isopropenylbenzene and diisopropenylbenzene, wherein the phenyl-substituted oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues of at least 20%; andthe oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants of at least 50%.

[0007] Another aspect of the disclosure is a polymerization reaction product of a polymerizable composition comprising the phenyl-substituted oligomer of the disclosure.

[0008] Another aspect of the disclosure is a thermosetting composition comprising the oligomer as described herein, present in an amount in the range of 1 to 60% on a dry solids basis; microparticulate silica, in an amount in the range of 15-50 wt% on a dry solids basis; an organic halogen-free fire retardant component, in an amount of 15-35 wt% on a dry solids basis; and an effective amount of a thermal free-radical initiator component (e.g., 0.1-4 wt% on a dry solids basis).

[0009] Of course, the thermosetting compositions can include a variety of other components, including a variety of other components that can react with the oligomer of the disclosure. For example, in various embodiments, the thermosetting compositions can include a poly(1,4-phenylene ether) component having at least 80% phenylene ether content, the poly(1,4-phenylene ether) component being a poly(1,4-phenylene ether) bis(meth)acrylate component, a bis(vinyl) poly(1 ,4-phenylene ether) component, or a bis((meth)allyl) poly(1,4-phenylene ether) component, or a combination of two or more thereof. Other possible components include trifunctional compounds like triallyl cyanurate and / or triallyl isocyanurate, various rubbers like styrene-butadiene rubbers, and various other resins like maleimide resins.

[0010] Another aspect of the disclosure is a cured (e.g., partially cured or substantially fully cured) product of a thermosetting composition as described herein.

[0011] Another aspect of the disclosure is a method for curing a thermosetting composition as described herein, the method comprising heating the thermosetting composition at a temperature of 150-250 °C.

[0012] Another aspect of the disclosure is a prepreg comprising a mesh substrate at least partially embedded in a cured product as described herein.

[0013] Another aspect of the disclosure is a laminate of a plurality of prepregs as described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a schematic cross-sectional view of a prepreg according to one embodiment of the disclosure.

[0015] FIG. 2 is a schematic cross-sectional view of a laminate according to one embodiment of the disclosure.DETAILED DESCRIPTION

[0016] The present inventors have developed particular thermosetting compositions using a phenyl-substituted oligomer that can provide not only good peel strength to copper, but also excellent dielectric properties at high frequency and good thermal properties.

[0017] One aspect of the disclosure is a phenyl-substituted oligomer that is a reaction product of an oligomerization mixture comprising one or more of styrene and divinylbenzene; and one or more of isopropenylbenzene and diisopropenylbenzene, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues of at least 20%; and the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants of at least 50%.

[0018] As described above, the oligomer has ratio of number of methyl-substituted vinyl residues to total number of vinyl resides of at least 20%. As used herein, a “vinyl residue” is a residue of any ethylenic unsaturation that is polymerized into the polymeric backbone, be it formally from a -CH=CH2 reactant, a -C(CH3)-CH2 reactant, a -CH=CH-CH3reactant, or any other ethylenic unsaturation. Vinyl residues also include any ethylenically unsaturated residues bound in the oligomer structure as endgroups of polyfunctional reactants. The present inventors have found that having methyl-substituted vinyl residues can help control the molecular weight of the oligomer. To control the molecular weight of the oligomer, various amounts of methyl-substituted vinyl residues may be used. For example, in some embodiments as described herein, the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues of at least 25%. As would be understood by the person of ordinary skill in the art, the ratio of the number of methyl-substituted vinyl residues to the total number of vinyl residues can be tuned based on the relative amounts of the one or more of isopropenylbenzene and diisopropenylbenzene and the one or more of styrene and divinylbenzene present in the oligomerization mixture (as well as the amounts of any other polymerizable components in the oligomerization mixture). For example, in various embodiments as described herein, a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues is at least 30%, or at least 35%, or at least 40%. In some embodiments as described herein, the oligomer has a ratio of number of methyl- substituted vinyl residues to total number of vinyl residues in the range of 20-90%. Forexample, in various embodiments, the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 20-80%, or 20-70%, or 20- 60%, or 20-50%. In various embodiment as described herein, the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 30-90% (e.g., in the range of 30-80%, or 30-70%, or 30-60%, or 30-50%, or 30-40%). In various embodiments as described herein, the oligomer has a ratio of number of methyl- substituted vinyl residues to total number of vinyl residues in the range of 40-90% (e.g., in the range of 40-80%, or 40-70%, or 40-60%, or 40-50%). In various embodiments, the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 50-90% (e.g., in the range of 50-80%, or 50-70%, or 50-60%). In various embodiments as described herein, the oligomer has a ratio of number of methyl- substituted vinyl residues to total number of vinyl residues in the range of 60-90% (e.g., in the range of 60-80%, or 60-70%). In various embodiments, the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 60-90% (e.g., in the range of 60-80%, or 60-70%, or 70-90%, or 70-80%). Not only can the methyl-substituted vinyl residues help control molecular weight of the oligomer, but they can advantageously prevent gelation during oligomerization, and also help to reduce thermal expansion in a polymer formed from the oligomer.

[0019] The oligomerization mixture also has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants of at least 50%. The ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants can be tuned based on the relative amounts diisopropenylbenzene and divinylbenzene to isopropenylbenzene and styrene present in the oligomerization mixture (i.e. , together with amounts of any other ethylenically-unsaturated reactants). For example, in various embodiments as described herein, the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants of at least 60%, at least 70%, at least 75%, or at least 80%. In some embodiments as described herein, the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 50-98%, e.g., 50-95% or 50-90%, or 50-85%, or 50-80%. In some embodiments as described herein, the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 60-98%, e.g., 60-95% or 60-90%, or 60-85%, or 60-80%. For example, in various embodiments as described herein, the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 70-98%, 70-95%, or 70-90%, or 70-85%, or 70-80%. In some embodiments as described herein, the oligomerization mixturehas a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 75-98%, e.g., 75-95% or 75-90%, or 75-85%. In some embodiments as described herein, the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 80-98%, e.g., 80-95%, or 80-90%.

[0020] As described above, the phenyl-substituted oligomer is a reaction product of an oligomerization mixture that includes one or more of divinylbenzene and styrene and one or more of isopropenylbenzene and diisopropenylbenzene. In some embodiments as described herein, the one or more of divinylbenzene and styrene is present in a range of 10- 80 wt% (e.g., 10-70 wt%, or 10-60 wt%, or 10-50 wt%) of polymerizable components of the oligomerization mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-90 wt% (e.g., 30-90 wt%, or 40-90 wt%, or 50-90 wt%) of polymerizable components of the oligomerization mixture. For example, in various embodiments, the one or more of divinylbenzene and styrene is present in a range of 20-80 wt% (e.g., 20-70 wt%, or 20-60 wt%, or 20-50 wt%, or 20-40 wt%) of polymerizable components of the oligomerizable mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-80 wt% (e.g., in the range of 30-80 wt%, or 40-80 wt%, or 50-80 wt%, or 60-80 wt%) of polymerizable components of the oligomerizable mixture. In various embodiments, the one or more of divinylbenzene and styrene is present in a range of 30-80 wt% (e.g., 30-70 wt%, or 30-60 wt%, or 30-50 wt%) of polymerizable components of the oligomerizable mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-70 wt% (e.g., in the range of 30-70 wt%, or 40-70 wt%, or 50-70 wt%) of polymerizable components of the oligomerizable mixture. In various embodiments, the one or more of divinylbenzene and styrene is present in a range of 40-80 wt% (e.g., 40-70 wt%, or 40-60 wt%) of polymerizable components of the oligomerizable mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-60 wt% (e.g., in the range of 30-60 wt%, or 40-60 wt%) of polymerizable components of the oligomerizable mixture.

[0021] In some embodiments as described herein, the oligomerization mixture has a molar ratio of the one or more of divinylbenzene and styrene to the one or more of isopropenylbenzene and diisopropenylbenzene of at least 0.2: 1. For example, in various embodiments, the molar ratio of the one or more of divinylbenzene and styrene to the one or more of isopropenylbenzene and diisopropenylbenzene in the oligomerizable mixture is at least 0.35:1, e.g., at least 0.5:1, or at least 0.75:1. In some embodiments, the oligomerization mixture has a molar ratio of the one or more of divinylbenzene and styrene to the one or more of isopropenylbenzene and diisopropenylbenzene of no more than 2:1.For example, in various embodiments, the molar ratio of one or more of divinylbenzene and styrene to one or more of isopropenylbenzene and diisopropenylbenzene in the oligomerizable mixture is no more than 1.5: 1 , or no more than 1.2:1, or no more than 1 :1. For example, in various embodiments as described herein, the molar ratio of the one or more of divinylbenzene and styrene to the one or more of isopropenylbenzene and diisopropenylbenzene is in the range of 0.2:1 to 2:1 (e.g., in the range of 0.2:1 to 1.5:1 , or 0.2:1 to 1.2:1, or 0.2:1 to 1:1 , or 0.35:1 to 2:1, or 0.35:1 to 1.5:1, or 0.35:1 to 1.2:1 , or 0.35:1 to 1:1 , or 0.5:1 to 2:1 , or 0.5:1 to 1.5:1 , or 0.5:1 to 1.2:1, or 0.5:1 to 1:1 , or 0.75:1 to 2:1 , or 0.75:1 to 1.5:1 , or 0.75:1 to 1.2:1 , or 0.75:1 to 1:1).

[0022] Divinylbenzene can be present in a variety of amounts in the oligomerizable mixture. For example, in various embodiments, the divinylbenzene is present in a range of 2-50 wt% (e.g., in the range of 2-30 wt%) of polymerizable components of the oligomerizable mixture. In various embodiments, the divinylbenzene is present in a range of 10-50 wt% (e.g., in the range of 10-30 wt%) of polymerizable components of the oligomerizable mixture. In various embodiments, the divinylbenzene is present in a range of 15-50 wt% (e.g., in the range of 15-40 wt%) of polymerizable components of the oligomerizable mixture.

[0023] The styrene can be present in a variety of amounts in the oligomerizable mixture. For example, in various embodiments, the styrene is present in a range of 10-50 wt% (e.g., in the range of 10-40 wt%, or 10-30 wt%) of polymerizable components of the oligomerizable mixture. In various embodiments, the styrene is present in a range of 15-50 wt% (e.g., in the range of 15-40 wt%, or 15-35 wt%) of polymerizable components of the oligomerizable mixture. In various embodiments, the styrene is present in a range of 20-50 wt% (e.g., in the range of 20-40 wt%, or 25-40 wt%) of polymerizable components of the oligomerizable mixture.

[0024] The one or more of isopropenylbenzene and diisopropenylbenzene can be present in a variety of amounts in the oligomerizable mixture. For example, in various embodiments, the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-90 wt% (e.g., in the range of 20-80 wt%, or 20-70 wt%, or 20-60 wt%) of polymerizable components of the oligomerizable mixture. In various embodiments, the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 30-90 wt% (e.g., in the range of 30-80 wt%, or 30-70 wt%, or 30-60 wt%) of polymerizable components of the oligomerization mixture. In various embodiments, the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 40-90 wt% (e.g., in the range of 40-80 wt%, or 40-70 wt%, or 40-60 wt%) of polymerizable components of the oligomerization mixture. In various embodiments, the isopropenylbenzene is present in arange of 20-90 wt% (e.g., in the range of 20-80 wt%, or 20-70 wt%, or 20-60 wt%) of polymerizable components of the oligomerizable mixture. In various embodiments, the diisopropenylbenzene is present in a range of 30-90 wt% (e.g., in the range of 30-80 wt%, or 30-70 wt%, or 30-60 wt%) of polymerizable components of the oligomerization mixture. In various embodiments, the diisopropenylbenzene is present in a range of 40-90 wt% (e.g., in the range of 40-80 wt%, or 40-70 wt%, or 40-60 wt%) of polymerizable components of the oligomerization mixture.

[0025] As described herein, the oligomerization mixture comprises one or more of divinylbenzene and styrene. In some embodiments as described herein, both divinylbenzene and styrene are included in the oligomerization mixture. As described herein, the oligomerization mixture includes one or more of isopropenylbenzene and diisopropenylbenzene. In some embodiments, the oligomerization mixture includes diisopropenylbenzene. For example, in some embodiments as described herein, the oligomerization mixture comprises divinylbenzene, styrene, and diisopropenylbenzene.

[0026] In some embodiments as described herein, the total amount of styrene, divinylbenzene, isopropenylbenzene and diisopropenylbenzene is at least 90 mol% of polymerizable components of the oligomerization mixture. For example, in various embodiments as described herein, the total amount of styrene, divinylbenzene, isopropenylbenzene and diisopropenylbenzene is at least 95 mol%, at least 98 mol% or at least 99 mol% of polymerizable components of the oligomerization mixture. Of course, the person of ordinary skill in the art can include other reactive components in the oligomerization mixtures.

[0027] In some embodiments as described herein, the oligomerizable reaction mixture has no more than 5 mol% of heteroatom-containing polymerizable components. For example, in various embodiments, the oligomerizable reaction mixture has no more than 2 mol%, no more than 1 mol%, or no more than 0.5 mol% of heteroatom-containing polymerizable components.

[0028] As described above, the oligomerization mixture comprises one or more divinylbenzene and styrene. The person of ordinary skill in the art would understand that diisopropenylbenzene has a variety of isomers. For example, in some embodiments as described herein, the divinylbenzene is one or more of 1,4-divinylbenzene and 1,3- divinylbenzene. For example, in some embodiments, the divinylbenzene is a mixture of both 1 ,4-divinylbenzene and 1,3-divinylbenzene. In some embodiments as described herein the divinylbenzene is primarily 1,4-divinylbenzene (e.g., 1,4-divinylbenzene with a minor amountof 1,3-divinylbenzene). In some embodiments as described herein the divinylbenzene is 1 ,4- divinylbenzene

[0029] The oligomerization mixture also comprises one or more of isopropenylbenzene and diisopropenylbenzene. As with divinylbenzene, the person of ordinary skill in the art would understand that diisopropenylbenzene has a variety of isomers. For example, in some embodiments as descried herein, the diisopropenylbenzene is one or more of 1,3- diisopropenylbenzene and 1,4-diisopropenylbenzene. In some embodiments as described herein the diisopropenylbenzene is 1,3-diisopropenylbenzene. In some embodiments, the diisopropenylbenzene is primarily 1 ,3-diisopropenylbenzene (e.g., with a minor amount of 1 ,4-diisopropenylbenzene).

[0030] Advantageously the present inventors have found that the inclusion of methylsubstituted vinyl residues can help control the molecular weight of the phenyl-substituted oligomer described herein. The person of ordinary skill in the art will select an appropriate molecular weight to provide the phenyl-substituted oligomer with desirable properties, e.g., a desirable viscosity to allow for processing into prepregs or other cured items. In some embodiments as described herein, the oligomer has a weight-average molecular weight in the range of 1000 to 15000 g / mol. For example, in various embodiments as described herein, the oligomer has a weight-average molecular weight in the range of 1000 to 12000 g / mol, or 1000 to 10000 g / mol, or 1000 to 8000 g / mol. In various embodiments, the oligomer has a weight-average molecular weight in the range of 1500 to 15000 g / mol, or 1500 to 12000 g / mol, or 1500 to 10000 g / mol, or 1500 to 8000 g / mol. In various embodiment as described herein, the oligomer has a weight-average molecular weight in the range of 2000 to 15000 g / mol, or 2000 to 12000 g / mol, or 2000 to 10000 g / mol, or 2000 to 8000 g / mol. Molecular weight is determined using gel-permeation chromatography (GPC) using monodisperse polystyrene standards. GPC can be used to measure the degree of oligomerization during the oligomerization reaction to provide the desire molecular weight.

[0031] As person of ordinary skill in the art would appreciate, the oligomerization mixture further includes a catalyst to induce oligomerization. The identity of the catalyst is not particularly limited. In some embodiments as described herein, the oligomerization mixture includes a free-radical initiator, and the oligomer is a free-radical-polymerized oligomer. In some embodiments as described herein, the oligomerization mixture includes a chain transfer catalyst and the oligomer is a catalytic chain transfer polymerized oligomer. For example, in some embodiments, the chain transfer catalyst is a cobalt chain transfer catalyst such as (H2O)2Co(dmgBF2)2. In some embodiments as described herein, theoligomerization mixture includes a cationic initiator, and the oligomer is a cationically- polymerized oligomer.

[0032] Another aspect of the disclosure is a polymerization reaction product of a polymerizable composition comprising the phenyl-substituted oligomer as described herein. In various embodiments, the polymerizable composition includes at least 5 wt% of the phenyl-substituted oligomer, e.g., at least 10 wt%. In various embodiments, the polymerizable composition includes at least 20 wt% of the phenyl-substituted oligomer, e.g., at least 30 wt%. In various embodiments, the polymerization reaction product is a free- radical polymerization reaction product. While particular embodiments are described herein with respect to materials for laminates and prepregs for electronics manufacturing, the person of ordinary skill in the art will appreciate that the oligomers of the disclosure can be useful in a wide variety of polymerizable compositions and reaction products.

[0033] In another aspect, the disclosure provides a thermosetting composition comprising: one or more free-radical polymerizable components, the one or more free-radical polymerizable components including the oligomer as described herein, present in an amount in the range of 1-69 wt% on a dry solids basis; micro particulate silica, in an amount in the range of 15-50 wt%; an organic halogen-free fire retardant component, in an amount of 15-35 wt%; and an effective amount of a thermal free-radical initiator component (e.g., 0.1-4 wt% on a dry solids basis).

[0034] As used herein, a thermosetting composition is a substantially liquid composition that cures from a liquid state to a solid state under the influence of heat. Various especially desirable thermosetting compositions are those that are “B-stageable,” that is, they can be partially cured to a manipulable solid under a first heat treatment, then later fully cured under a second heat treatment. The partially cured material can be, for example, in a so-called “B- stage,” and can be further cured to a so-called “C-stage.” The person of ordinary skill in the art of electronic materials is familiar with the use of thermosetting compositions like those described herein in the production of a variety of products such as prepregs, resin films, resin-coated copper, laminates, and printed circuit boards.

[0035] One component of the thermosetting composition is the phenyl-substituted oligomer as described herein. In some embodiments as described herein, the oligomer is present in an amount in the range of 1-50 wt% (e.g., in the range of 1-40 wt%, or 1-35 wt%, or 1-30 wt%, or 1-25 wt%) on a dry solids basis. For example, in various embodiments, the oligomer is present in an amount in the range of 2-69 wt%, e.g., 2-50 wt%, or 2-40 wt%, or2-35 wt%, or 2-30 wt%, or 2-25 wt%, on a dry solids basis. In various embodiments, the oligomer is present in an amount in the range of 5-69 wt%, e.g., 5-50 wt%, or 5-40 wt%, or 5-35 wt%, or 5-30 wt%, or 5-25 wt%, on a dry solids basis. In various embodiments, the oligomer is present in an amount in the range of 10-69 wt%, e.g., 10-50 wt%, or 10-40 wt%, or 10-35 wt%, or 10-30 wt%, or 10-25 wt%, on a dry solids basis. Using the phenylsubstituted oligomer in the thermosetting composition can replace other commonly used aromatic crosslinking components, e.g., a cyanurate or isocyanurate component, to help reduce the dielectric loss of the thermosetting composition.

[0036] The person of ordinary skill in the art can select a variety of additional free-radical polymerizable components for use in the thermosetting compositions described herein. For example, in various embodiments, the one or more polymerizable components further comprises a poly(1 ,4-phenylene ether) component having at least 80% phenylene ether content, the poly(1,4-phenylene ether) component being a poly(1,4-phenylene ether) bis(meth)acrylate component, a bis(vinyl) poly(1 ,4-phenylene ether) component, or a bis((meth)allyl) poly(1,4-phenylene ether) component, or a combination of two or more thereof. The poly(1,4-phenylene ether) component can be made of a single sample of a poly(1 ,4-phenylene ether) bis(meth)acrylate, bis(vinyl), or bis((meth)allyl) polymer (which itself would typically have a range of molecules of different degrees of polymerization), or a blend of multiple samples of poly(1 ,4-phenylene ether) bis(meth)acrylate, bis(vinyl), or bis((meth)allyl) polymers.

[0037] The poly(1 ,4-phenylene ether) component has at least 80 wt% phenylene ether content. This means that at least 80 wt% of the component is made up of -□-(optionally- substituted phenylene) groups. In various embodiments, the mass of the (optionally- substituted phenylene) groups of the -O-(optionally-substituted phenylene) content of the poly(1 ,4-phenylene ether) component is made up of at least 50% phenyl carbons and phenyl hydrogens.

[0038] The poly(1 ,4-phenylene ether) component, in various desirable embodiments, is a poly(1,4-phenylene ether) bismethacrylate component, i.e. , having at least 75 wt%, e.g., at least 90 wt% poly(1,4-phenylene ether) bismethacrylate.

[0039] In various embodiments, the poly(1,4-phenylene ether) component is a bis(vinyl) poly(1 ,4-phenylene ether) component, i.e., having at least 75 wt%, e.g., at least 90 wt% bis(vinyl) poly(1,4-phenylene ether).

[0040] In various embodiments, the poly(1,4-phenylene ether) component is a bis(allyl) poly(1 ,4-phenylene ether) component, i.e., having at least 75 wt%, e.g., at least 90 wt% bis(allyl) poly(1 ,4-phenylene ether).

[0041] In various embodiments, the poly(1 ,4-phenylene ether) component is a bis(methallyl) poly(1 ,4-phenylene ether) component, i.e., having at least 75 wt%, e.g., at least 90 wt% bis(methallyl) poly(1 ,4-phenylene ether).

[0042] In various embodiments, the poly(1 ,4-phenylene ether) component has the structural formulain which A is a bond, -CH2-, CH(CH3)-, -C(CH3)2-, -O-, -C(O)-, S(O), or S(O)2; each R1is independently methacrylate, acrylate, vinyl, allyl or methallyl; each R2is independently methyl or hydrogen; and each R3is independently methyl or hydrogen. Mixtures of molecules having different identities of A, R1and R2are specifically contemplated within this definition. As the person of ordinary skill in the art will appreciate, values of x and y will vary depending on the molecular weight of the material.

[0043] For example, in various embodiments, A is -CH2-, CH(CH3)- or -C(CH3)2-. In various embodiments, A is -C(CH3)2-.

[0044] The structure of the tetra-R2-substituted moieties can vary. For example, in various embodiments, in at least 75% of themoieties, two R2are methyl and two R2are H. For example, in various embodiments, in in at least 90% of themoieties two R2are methyl and two R2 are H. in various embodiments, in in at least 98% of themoieties two R2are methyl and two R2are H.

[0045] In various embodiments, in at least 75% of themoieties, two R2are methyl substituted in a meta relationship and two R2are H. For example, in various embodiments, in in at least 90% of themoieties two R2are methyl substituted in a meta relationship and two R2are H. in various embodiments, in in at least98% of themoieties two R2are methyl substituted in a meta relationship and two R2are H.

[0046] In various embodiments, in at least 75% of themoieties, two R2are methyl substituted in a meta relationship distal to the A moiety and two R2are H. For example, in various embodiments, in in at least 90% of themoieties two R2are methyl substituted in a meta relationship distal to the A moiety and two R2are H. invarious embodiments, in in at least 98% of themoieties two R2are methyl substituted in a meta relationship distal to the A moiety and two R2are H.

[0047] The structure of the tetra-R3-substituted moieties can also vary. For example, in various embodiments, in at least 75% of themoieties, two R3are methyl and two R3are H. For example, in various embodiments, in in at least 90% of themoieties two R3are methyl and two R3are H. in various embodiments, in in at least 98% of themoieties two R3are methyl and two R3are H.

[0048] In various embodiments, in at least 75% of themoieties, two R3are methyl substituted in a meta relationship and two R3are H. For example, in various embodiments, in in at least 90% of themoieties two R3are methyl substituted in a meta relationship and two R3are H. in various embodiments, in in at least98% of themoieties two R3are methyl substituted in a meta relationship and two R3are H.

[0049] In various embodiments, in at least 75% of themoieties, two R3are methyl substituted in a meta relationship distal to the A moiety and two R3are H. For example, in various embodiments, in in at least 90% of themoieties two R3are methyl substituted in a meta relationship distal to the A moiety and two R3are H. in various embodiments, in in at least 98% of themoieties two R3are methyl substituted in a meta relationship distal to the A moiety and two R3are H.

[0050] As noted above, R1can be one or more of methacrylate, acrylate, vinyl, allyl and methallyl. In various embodiments, at least 75% of R1are methacrylate, e.g., at least 90%, or at least 95%. In various embodiments, at least 75% of R1are vinyl, e.g., at least 90%, or at least 95%. In various embodiments, at least 75% of R1are allyl, e.g., at least 90%, or at least 95%. In various embodiments, at least 75% of R1are methallyl, e.g., at least 90%, or at least 95%. In various embodiments, at least 75% of R1are methacrylate, vinyl, allyl or methallyl, e.g., at least 90%, or at least 95%.

[0051] In various particular embodiments, at least 75 wt% of the poly( 1 ,4-phenylene ether) component has the formula. In various such embodiments, at least 90 wt% of the poly(1 ,4-phenylene ether) component has this formula. In various such embodiments, at least 95 wt% of the poly(1,4-phenylene ether) component has this formula.

[0052] The poly(1 ,4-phenylene ether) component can have a variety of molecular weights. The person of ordinary skill in the art will select an appropriate molecular weight to provide the thermosetting composition with desirable properties, e.g., a desirable viscosity to allow for processing into prepregs or other cured items. For example, in various embodiments, the poly(1,4-phenylene ether) component has a number-average molecular weight in the range of 1000-4000 g / mol, e.g., 1000-3500 g / mol or 1000-3000 g / mol, or 1000- 2500 g / mol, or 1500-4000 g / mol, or 1500-3500 g / mol, or 1500-2500 g / mol.

[0053] As noted above, the values of x and y will depend on the molecular weight of the material. In various embodiments, the poly(1 ,4-phenylene ether) component has a numberaverage value of the sum of x+y in the range of 3-30, e.g., 3-25, or 3-20, or 3-15, or 5-30, or 5-25, or 5-20, or 5-15, or 7-30, or 7-25, or 7-20, or 7-15, or 10-30, or 10-25, or 10-20, or ID- 15.

[0054] Examples of suitable materials include NORYL SA-9000, available from SABIC; Kolon KPU-6000, available from Kolon Industries; and SP7-160, available from SilverAge Engineering Plastics Co Ltd.

[0055] The poly(1 ,4-phenylene ether) component can be present in the thermosetting composition in a variety of amounts. For example, in some embodiments, the poly(1 ,4- phenylene ether) component is present in the thermosetting composition in an amount in the range of 5-50 wt%. For example, in various embodiments the poly(1,4-phenylene ether) component is present in an amount in the range of 5-30 wt%, or 5-25 wt%, or 5-20 wt%, on a dry solids basis. In various embodiments, the poly(1,4-phenylene ether) component is present in an amount in the range of 10-50 wt%, e.g., 10-30 wt%, or 10-25 wt%, or 10-20 wt%, on a dry solids basis.

[0056] A variety of other free-radical polymerizable components can be included.

[0057] In various embodiments, the one or more free-radical polymerizable components further includes an aromatic crosslinking component having a weight average molecular weight of no greater than 700 g / mol and bearing on numerical average in the range of 1.75 - 3.5 crosslinkable vinyl, (meth)allyl and / or (meth)acrylate groups per molecule, in an amount up to 10 wt%, on a dry solids basis. While the oligomer of the disclosure can replace some, or even all of such crosslinking components, it can be desirable in some embodiments to maintain some present in the thermosetting composition.

[0058] The person of ordinary skill in the art will appreciate that a variety of such aromatic crosslinking components may be used, alone or in combination. For example, in various desirable embodiments, the aromatic crosslinking component includes (or is) acyanurate component. In various embodiments, the aromatic crosslinking component includes (or is) is a cyanurate component that is triallylcyanurate, triallylisocyanurate, or a combination of triallylcyanurate and triallylisocyanurate. For example, in some embodiments, the aromatic crosslinking component includes (or is) triallylcyanurate. In some embodiments, the aromatic crosslinking component includes (or is) triallylisocyanurate. In some embodiments, the aromatic crosslinking component includes (or is) a combination of triallylcyanurate and triallylisocanurate. In some embodiments, the aromatic crosslinking component includes (or is) trimethallylisocyanurate.

[0059] But the person of ordinary skill in the art will appreciate that other aromatic crosslinkers can be used, in combination with or instead of the cyanurate materials described above. For example, in various embodiments, the aromatic crosslinking component includes (or is) a divinylbenzene.

[0060] In various embodiments, the aromatic crosslinking component includes (or is) triallylcyanurate, triallylisocyanurate, trimethallylisocyanurate, divinylbenzene, or any combination thereof.

[0061] Aromatic crosslinking components such as those described above are widely available from various vendors.

[0062] The thermosetting compositions described herein can include the aromatic crosslinking component in a variety of amounts. For example, in various embodiments, the aromatic crosslinking component is present in an amount in the range of 0-8 wt%, e.g., 0-6 wt%, on a dry solids basis. In various embodiments, the aromatic crosslinking component is present in an amount in the range of 2-10 wt%, e.g., 2-8 wt%, or 2-6 wt%, on a dry solids basis. In various embodiments, the aromatic crosslinking component is present in an amount in the range of 3-10 wt%, e.g., 3-8 wt%, or 3-6 wt%, on a dry solids basis. The person of ordinary skill in the art can tune the amount of aromatic crosslinking component to provide desired properties to cured materials.

[0063] In some embodiments as described herein, the one or more free-radical polymerizable components of the thermosetting composition further includes a butadiene / styrene copolymeric rubber component, in an amount of 5-25 wt% of the thermosetting composition, on a dry solids basis. As used herein, a butadiene / styrene copolymeric rubber is a polymer that is formed of at least 80 wt% butadiene and styrene residues, and has a glass transition temperature as measured by DSC of no more than 5 °C. The corresponding component of the thermosetting composition can include one or more such samples of rubber.

[0064] In various embodiments, the butadiene / styrene copolymeric rubber component has a total content of butadiene and styrene residues in an amount of at least 90 wt%, e.g., at least 95 wt%, at least 97 wt%, at least 98 wt%, or at least 99 wt%.

[0065] In various embodiments, however, the butadiene / styrene copolymeric rubber component includes a substantial amount of other residues. For example, in some embodiments, the butadiene / styrene copolymeric rubber component includes divinylbenzene residues, e.g., grafted to a butadiene / styrene backbone. In various embodiments, the butadiene / styrene copolymeric rubber component comprises up to 5 wt% divinylbenzene residues, e.g., in the range of 0.5-5 wt%, or 0.5-3 wt%, or 1-5 wt%, or 1-3 wt%.

[0066] In various embodiments as otherwise described herein, the butadiene / styrene copolymeric rubber component has a substantially random arrangement of butadiene and styrene. The person of ordinary skill in the art will appreciate that such materials can be made by copolymerization of butadiene and styrene in a single process. However, in alternative embodiments, copolymers that have substantial block copolymer character can be used.

[0067] In various embodiments, the butadiene / styrene copolymeric rubber component has a number average molecular weight in the range of 1500-7000 g / mol, e.g., 1500-5000 g / mol, or 2500-7000 g / mol, or 2500-5000 g / mol.

[0068] The amount of 1 ,2-vinyl moieties of the butadiene / styrene substantially random copolymeric rubber component can vary. In various embodiments, the butadiene residues of the butadiene / styrene copolymeric rubber component have a molar fraction of 1 ,2-vinyl moieties in the range of 15-80 mol%, e.g., 15-70%, or 15-60%, or 20-80 mol%, or 20-70 mol%, or 20-60 mol%. In various embodiments, the butadiene residues of the butadiene / styrene copolymeric rubber component have a molar fraction of 1 ,2-vinyl moieties of 25-80 mol%, e.g., 25-70%, or 25-60%, or 30-80 mol%, or 30-70 mol%, or 30-60 mol%. In various embodiments, the butadiene residues of the butadiene / styrene copolymeric rubber component have a molar fraction of 1 ,2-vinyl moieties of 35-80 mol%, e.g., 35-70%, or 35- 60%, or 40-80 mol%, or 40-70 mol%, or 40-60 mol%. In various embodiments, the butadiene residues of the butadiene / styrene copolymeric rubber component have a molar fraction of 1 ,2-vinyl moieties of 20-60 mol%, e.g., 20-55 mol%, or 20-50 mol%, or 20-45 mol%, or 25-60 mol%, or 25-55 mol%, or 25-50 mol%, or 25-45 mol%, or 30-60 mol%, or 30-55 mol%, or 30- 50 mol%, or 30-45 mol%, or 35-60 mol%, or 35-55 mol%, or 35-50 mol%, or 35-45 mol%.

[0069] The amount of styrene residues in the butadiene / styrene copolymeric rubber component can vary as well. In various embodiments, the butadiene / styrene substantiallyrandom copolymeric rubber component has in the range of 15-40 wt% styrene residues, e.g., 15-35 wt% or 15-30 wt%. In various embodiments, the butadiene / styrene copolymeric rubber component has in the range of 20-40 wt% styrene residues, e.g., 20-35 wt% or 20-30 wt%. In various embodiments, the butadiene / styrene copolymeric rubber component has in the range of 23-40 wt% styrene residues, e.g., 23-35 wt% or 23-30 wt%.

[0070] While the butadiene / styrene copolymeric rubber component can be made substantially of a single sample of butadiene / styrene copolymeric rubber, in some cases, blends can be used. For example, in various embodiments, the butadiene / styrene copolymeric rubber component is made up of a first butadiene / styrene substantially random copolymeric rubber subcomponent that has 17-27 wt% styrene residues and in which the butadiene residues have a molar fraction of 1 ,2-vinyl moieties of 60-80 mol%; and a second butadiene / styrene substantially random copolymeric rubber subcomponent that has 20-30 wt% styrene residues and in which the butadiene residues have a molar fraction of 1 ,2-vinyl moieties of 20-40 mol%. In various such embodiments, a weight ratio of the first butadiene / styrene substantially random copolymeric rubber subcomponent and the second butadiene / styrene substantially random copolymeric rubber subcomponent is in the range of 1:1.2 - 1:2.3, e.g., 1 :1.5 - 1:2.3, or 1:1.2 - 1:2, or 1 :1.5 - 1 :2.

[0071] Butadiene / styrene substantially random copolymeric rubber materials are available from a variety of vendors, including Cray Valley (e.g., Ricon 100, Ricon 181 , Ricon 184, Ricon 257) and Kuraray Co., Ltd. (L-SBR grades, including L-SBR-870, L-SBR-822 and L-SBR-841). Block copolymer materials are also widely available.

[0072] The amount of the butadiene / styrene copolymeric rubber component in the thermosetting composition can vary. For example, in various embodiments, the butadiene / styrene copolymeric rubber component is present in an amount in the range of 5- 20 wt%, or 5-18 wt%, or 5-15 wt%. In various embodiments, the butadiene / styrene copolymeric rubber component is present in an amount in the range of 7-25 wt%, e.g., 7-20 wt%, or 7-18 wt%, or 7-15 wt%. In various embodiments, the butadiene / styrene substantially random copolymeric rubber component is present in an amount in the range of 9-25 wt%, e.g., 9-20 wt%, or 9-18 wt%, or 9-15 wt%.

[0073] In some embodiments as described herein, the thermosetting composition further includes a maleimide resin. A wide variety of maleimide resins can be suitable for use in the thermosetting compositions of the disclosure. As used herein, a maleimide resin comprises a maleimide-bearing components and has on a number average at least 2 maleimides per molecule. The present inventors have noted that use of such materials can enhance toughness and thermal reliability and reduce warpage in materials made with thethermosetting compositions. Moreover, they can help to improve solubility of components within the thermosetting composition overall.

[0074] In various embodiments, the maleimide resin has at least 4 maleimides per molecule, e.g., at least 5, or at least 6, on number average. In various embodiments, the maleimide resin has in the range of 3-10 maleimides per molecule, e.g., in the range of 4-10, or 5-10, or 6-10, or 3-9, or 4-9, or 5-9, or 6-9, on number average. In various embodiments, the maleimide resin component has in the range of 3-8 maleimides per molecule, e.g., in the range of 4-8, or 5-8, or 6-8, or 3-7, or 4-7, or 5-7, on number average.

[0075] The maleimide resin desirably has a relatively high aromatic carbon content, in order to improve thermal stability and various other properties. In various embodiments as otherwise described herein, the maleimide resin component an aromatic carbon fraction of at least 80%, e.g., at least 84%, or at least 88%.

[0076] Examples of maleimide resins include compounds like 4,4'-diphenylmethane bismaleimide, phenylmethane maleimide, m-phenylene bismaleimide, 2,2'-bis[4-(4- maleimidophenoxy)phenyl]propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide and 1,6'-bismaleimide-(2,2,4- trimethyl)hexane, as well as oligomers having the general structures shown below:where n and n6 are selected to provide a number of maleimide residues as described above.

[0077] Maleimide resins are available from a variety of vendors, including Nippon Kayaku (e.g., MIR-3000 and MIR-5000) and Daiwakasei Industry Co. Ltd. (e.g., BMI1100).

[0078] The amount of the maleimide resin in the thermosetting composition can vary. For example, in some embodiments, the maleimide resin is present in an amount in the range of 1-10 wt%. In various embodiments, the maleimide resin is present in an amount in the range of 1-8 wt%, e.g., 1-6 wt%. For example, in various embodiments as described herein, the maleimide resin is present in an amount in the range of 2-10 wt%, e.g., 2-8 wt%, or 2-6 wt%. In various embodiments, the maleimide resin is present in an amount in the range of 3-10 wt%, e.g., 3-8 wt%, or 3-6 wt%.

[0079] The thermosetting composition also includes micro particulate silica, in an amount in the range of 15-50 wt%. As used herein, a micro particulate silica is a particulate material that is at least 95 wt% SiC>2 and has a dso particle size in the range of 0.1-100 microns. As used herein, the d50 particle size is the median particle size, i.e. , the size of the particle at which 50% of the particles are of larger particle size and 50% are of smaller particle size. As used herein, “particle size” is the largest dimension of the particle. In various embodiments, the microparticulate silica has a dso particle size in the range of 0.5-10 microns, e.g., 0.5-7 microns, or 0.5-5 microns, or 1-10 microns, or 1-7 microns, or 1-5 microns. In various embodiments, the microparticulate silica has a dgo particle size in the range of 1-20 microns, e.g., 1-14 microns, or 1-8 microns, or 3-20 microns, or 3-14 microns, or 3-8 microns. In various embodiments, the microparticulate silica has a d particle size in the range of 0.1-5 microns, e.g., 0.1-3 microns, or 0.1-2 microns, or 0.5-5 microns, or 0.5-3 microns, or 0.5-2 microns. In various embodiments, the microparticulate silica has at least 99 wt% SiC>2, e.g., at least 99.5 wt% SiC>2.

[0080] The micro particulate silica is desirably substantially spherical. The person of ordinary skill in the art can use microscopy to confirm sphericity.

[0081] Suitable microparticulate silicas are available from a variety of vendors, including DQ-1028L, available from Novoray; SS-15V, available from Sibelco; and FB-3SDC and FB- 3SDX, available from Denka Co. Ltd.

[0082] The amount of microparticulate silica can vary. For example, in various embodiments, the microparticulate silica is present in an amount in the range of 15-45 wt%, or 15-40 wt%, or 15-35 wt%. In various particular embodiments, the microparticulate silica is present in an amount in the range of 20-50 wt%, e.g., 20-45 wt%, or 20-40 wt%, or 20-35 wt%. In various particular embodiments, the microparticulate silica is present in an amount in the range of 25-50 wt%, e.g., 25-45 wt%, or 25-40 wt%, or 25-35 wt%.

[0083] The thermosetting composition also includes an organic halogen-free fire retardant component, present in an amount of 15-35 wt%. In various embodiments, the organic halogen-free fire retardant comprises phosphorus.

[0084] Notably, the present inventors have found that particular fire retardants described in U.S. Patents nos.8536256, 9012546, 9522927 and 9562063 can provide especially good performance in the presently-described thermosetting compositions. Accordingly, these patents are hereby incorporated herein by reference in their entirety, and their text is copied below; the present disclosure contemplates the use of any fire retardant as generically or specifically described in any of these patents as part of the organic halogen-free fire retardant component of the thermosetting composition of the disclosure, alone or in combination. For example, in various embodiments, the organic halogen-free fire retardant component includes (or is) 6H-Dibenz[c,e][1 ,2]oxaphosphorin, 6,6'-(1 ,4-ethanediyl)bis-, 6,6'- dioxide; 6H-Dibenz[c,e][1 ,2]oxaphosphorin, 6,6'-(1,4-butanediyl)bis-,6,6'-dioxide; or 6H- Dibenz[c,e][1,2]oxaphosphorin, 6,6'-(p-xylenediyl)bis-,6,6'-dioxide; or any combination thereof. In various embodiments, the fire retardant component includes (or is) is 6H- Dibenz[c,e][1,2]oxaphosphorin, 6,6'-(1 ,4-ethanediyl)bis-, 6,6'-dioxide. In various embodiments, the fire retardant component includes (or is) a compound having the structure: having the following structure:In various embodiments, the fire retardant component includes (or is) composition comprising the high melting point isomer of Formula Ila:Formula Ilaand the low melting point isomers of Formula lib and He having the Formulas:Formula libwherein said composition has an Isomer Ratio of greater than about 0.5 utilizing the 31 P NMR method and wherein said Isomer Ratio=Ah / (Ah+Ai), wherein Ah: area of high melting point isomer peak and Ai: area of low melting point isomers peak.

[0085] But in other embodiments, other halogen-free flame retardants can be used. In various embodiments, the organic halogen-free fire retardant is a phosphorus-containing fire retardant, e.g., selected from FRM 6300 (Qingdao) and Mosaflam 615 (UFC).

[0086] The organic halogen-free fire retardant component can be provided in the thermosetting composition in a variety of amounts within the broader range of 15-35 wt%. For example, in various embodiments, the organic halogen-free fire retardant component is present in an amount of 15-30 wt%, e.g., 15-25 wt%. In various embodiments, the organic halogen-free fire retardant component is present in an amount of 20-35 wt%, e.g., 20-30 wt%, or 20-25 wt%. In various embodiments, the organic halogen-free fire retardant component is present in an amount of 25-35 wt%, e.g., 25-30 wt%.

[0087] As noted above, the thermosetting composition also includes an effective amount of a thermal free-radical initiator component. The person of ordinary skill in the art will identify a desirable thermal free-radical initiator or combination thereof, in desirable amount(s) to provide initial polymerization of the thermosetting composition to a B-staged composition, and to further polymerize the B-staged composition to a substantially- polymerized composition, e.g., in laminate form. Suitable initiators include, without limitation, benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, lauryl peroxide, cyclohexanone peroxide, t-butyl hydroperoxide, t-butyl benzene hydroperoxide, acetylisobutyryl peroxide, diacetyl peroxide, t-butyl peroctoate, a,a'-bis(t-butylperoxy-m- isopropyl)benzene, 2,3-dimethyl-2,3-diphenylbutane, di(trimethylsilyl)peroxide, ,5-dimethyl- 2,5-di(benzoylperoxy)hexane, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5- di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t- butylperoxy)hexane, t-butylperoxy benzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t- butylperoxy)octane, 2trimethylsilylphenyltriphenylsilyl peroxide, 2,3-trimethylsilyloxy-2,3- diphenylbutane, di(t-butylperoxy) isophthalate, azobisisobutyronitrile (AIBN), azobis(2- isopropyl)butyronitrile, 2,2'-azobis(2,4-dimethyl)valeronitrile (AVBN), (2,4-dichlorobenzoyl) peroxide, (2-dimethylbenzoyl) peroxide, and dodecanoyl peroxide. The person of ordinary skill in the art can provide the initiator component with a single initiator or a combination of initiators. The one or more initiators can be provided in some embodiments with a carrier; the person of ordinary skill in the art will appreciate that the mass of the thermal free-radical initiator component is calculated as the mass of the initiator compound(s) themselves, omitting the mass of any carriers.

[0088] The person of ordinary will determine an effective amount of the thermal free- radical initiator component. For example, in various embodiments, the thermal free-radical initiator component is present in an amount in the range of 0.05-4 wt%, e.g., 0.05-2 wt%, or 0.05-1 wt%, or 0.05-0.7 wt%. In various embodiments, the thermal free-radical initiator component is present in an amount in the range of 0.07-4 wt%, e.g., 0.07-2 wt%, or 0.07-1 wt%, or 0.07-0.7 wt%. In various embodiments, the thermal free-radical initiator component is present in an amount in the range of 0.1-4 wt%, e.g., 0.1-2 wt%, or 0.1-1 wt%, or 0.1-0.7 wt%. In various embodiments, the thermal free-radical initiator component is present in an amount in the range of 0.2-4 wt%, e.g., 0.2-2 wt%, or 0.2-1 wt%, or 0.2-0.7 wt%.

[0089] Additional components than those outlined above can be present in some embodiments. For example, in various embodiments, the thermosetting composition can also include a silane coupling agent, e.g., to provide bonding to the micro particulate silica filler and / or to a glass material used in making a prepreg or laminate. The person of ordinary skill in the art is familiar with silane coupling agents, and can select a suitable one based on the description herein. For example, the silane coupling agent can in some embodiments be selected from one or more of (meth)acryl-functional silanes (e.g., 3- (meth)acryloxy)propyltrimethoxysilane), vinyl-functional silanes (e.g., vinyltriethoxysilane), allyl-functional silanes (e.g., allyltrimethoxysilane), and other reactive carbon-carbon double-bond- bearing silanes (e.g., styryltrimethoxysilane, 3-butenyltriethoxysilane, 7- octenyltriethoxysilane). The silane coupling agent can be present in an amount, e.g., up to 5 wt%, e.g., in the range of 0.1-5 wt%. However, the present inventors have noted that asilane coupling agent in many embodiments is not necessary for good performance, and so in various embodiments, there is no more than 0.01 wt% of a silane coupling agent present.

[0090] The amounts described herein for components of the thermosetting composition are on a dry solids basis, i.e., with 100 wt% being the total of the non-volatile (i.e., boiling point less than 200 °C at atmospheric pressure) components of the composition. In various embodiments, the thermosetting composition is provided in substantially non-volatile form, i.e., without a substantial amount of a solvent. The present inventors have noted that thermosetting compositions as described here can in many embodiments be provided with desirable viscosities without the use of large amounts of solvent. Accordingly, in various embodiments, the thermosetting compositions as described herein can be provided with no more than 10 wt% material having a boiling point at atmospheric pressure of less than 200 °C, e.g., no more than 5 wt%, or no more than 3 wt%, or no more than 1 wt%, all calculated with the non-volatile content being 100 wt% as described above.

[0091] However, the present inventors note that a solvent can be useful to provide the material with a lower viscosity for processing, especially in the impregnation of a glass or polymer fabric for making a prepreg. Accordingly, in various embodiments, the thermosetting composition also includes a solvent having a boiling point at atmospheric pressure of less than 200 °C. The person of ordinary skill in the art will appreciate that a variety of solvents could be used, alone or in combination, and will determine an appropriate solvent in which to suspend the various components of the composition. Potential examples include y-butyrolactone, cyclohexanone, butanone, methyl isobutyl ketone, N,N- dimethylformamide, propylene glycol monomethyl ether, N,N-dimethylacetamide, ethylene glycol monomethyl ether, methoxy ethyl acetate, ethoxy ethyl acetate, propoxy ethyl acetate, diisobutyl ketone (DIBK), N-methyl-pyrrolidone., xylene, ethyl acetate, toluene, trichloroethane, dibutyl ether, methyl ethyl ketone, and acetone. Similarly, the person of ordinary skill in the art will appreciate that the amount of solvent can be varied to provide a desired viscosity; in various embodiments, the amount of solvent is up to 60 wt%, e.g., in the range of 20-60 wt%, in excess of the non-volatile components of the thermosetting composition (i.e., taken together as 100 wt%).

[0092] Another aspect of the disclosure is a cured product of a thermosetting composition as described herein. As the person of ordinary skill in the art will appreciate, the cured product can in some embodiments be only partially-cured, e.g., to an extent to form a solid form, such that it is handleable but can be more fully cured by further processing. This partial curing can be to a so-called “B-stage,” or to a lesser or further extent. In other embodiments, the cured product can be substantially fully cured, so that it issubstantially stable to further processing. A variety of curing conditions may be used, but typically curing temperatures are in the range of 100-250 °C, for a time sufficient to arrive at a desired degree of cure.

[0093] Another aspect of the disclosure is a prepreg comprising a mesh substrate at least partially embedded in a cured product of the disclosure, desirably a partially-cured product that can be further cured by further heating at a later time. One embodiment is shown in schematic cross-sectional view in FIG. 1. Here, prepreg 100 comprises mesh substrate 110, embedded in a cured product of the disclosure 120.

[0094] The person of ordinary skill in the art can use a variety of mesh substrates. For example, in various embodiments, the mesh substrate is a fabric (woven or non-woven), e.g., made from glass fiber, carbon fiber, or various polymer fibers such as aramid fiber such as the material available under the trade name KEVLAR. In particular desirable embodiments, the substrate is a borosilicate glass fabric. In some such embodiments, the glass is formed, on an oxide basis, of SiC>2 (50-80 wt%), B2O3 (5-25 wt%), with optional components including without limitation CaO (up to 30 wt%) AI2O3 (up to 20 wt%) and MgO (up to 5 wt%). Examples of suitable glass fabrics include electronic grade E-glass fabric, NE- glass fabric, D-glass fabric, and S-glass fabric. In various embodiments, the mesh substrate is substantially embedded in the cured product. As the person of ordinary skill in the art will appreciate, prepregs can be made of a variety of overall thicknesses, but in some embodiments, the prepreg is in the range of 10-300 microns in thickness, e.g., 10-200 microns, or 10-150 microns, or 10-100 microns. In some embodiments, the prepreg is in the range of 25-300 microns in thickness, e.g., 25-200 microns, or 25-150 microns, or 25-100 microns. In some embodiments, the prepreg is in the range of 50-300 microns in thickness, e.g., 50-200 microns, or 50-150 microns. The prepreg desirably includes at least 30 wt% of the cured product of the disclosure, e.g., at least 50 wt%.

[0095] The person of ordinary skill in the art is familiar with methods for making prepregs, and will adapt such methods for use with the thermosetting composition of the disclosure. The thermosetting composition can be contacted with the mesh substrate, dried as necessary to remove any volatiles, and cured by heating to cause the thermosetting composition to at least partially cure it to provide the prepreg.

[0096] Another aspect of the disclosure is a laminate of a plurality of prepregs of the present disclosure. One example is shown in schematic perspective view in FIG. 2. Here, laminate 230 includes a laminate of a plurality of prepregs 200. The laminate can be made by heat-pressing a plurality of prepregs as described herein to cause softening and further curing of partially-cured material of the prepregs to fuse them together into a laminatestructure. Heat pressing conditions can vary, but can generally be in the range of 150-250 °C and 1-10 MPa. The further curing in many embodiments can substantially fully cure the material. As used herein, substantial full curing can be determined using a delta Tg measurement, in which a material is run to 250 °C in a differential scanning calorimeter and a first Tg determined. The sample is then cooled to room temperature, and a Tg measurement up to 250 °C is repeated to provide a second Tg. If the difference between the first Tg and the second Tg is no more than 10 °C, the material is said to be substantially fully cured. Here, too, the person of ordinary skill in the art is familiar with techniques for forming laminates from prepregs, and will adapt them for use with the prepregs of the disclosure.

[0097] The laminates of the disclosure can include one or more layers of metal, such as copper. The one or more layers of metal can be disposed, e.g., on one or both major surfaces of the laminate, and / or laminated in between layers of prepregs. Each layer of metal can be substantially uniform, or can be provided in the form of circuits, e.g., by etching. As the person of ordinary skill in the art will appreciate, a circuit board laminate can be built in a plurality of steps, e.g., by providing a first laminate with metal on one or both surfaces thereof, then forming a circuit out of such metal, then further laminating the so- processed first laminate with additional layers of prepreg and metal to form a multilayer laminate.

[0098] The present inventors have found that the materials described herein have a variety of desirable properties, including low Df values, good peel strength, and high glass transition temperature. For example, in various embodiments, the laminate has a Df value in the range of 0.0010 to 0.003, e.g., 0.0010 to 0.0025, or 0.0010 to 0.0020, as measured by IPC-TM-6502.5.59. In some embodiments as described herein, the laminate has a Df value in the range of 0.0012 to 0.003, e.g., 0.0012 to 0.0025, or 0.0012 to 0.0020, as measured by IPC-TM-6502.5.59. In some embodiments as described herein, the laminate has a Dk value in the range of 3.0 to 3.5, e.g., in the range of 3.0 to 3.4, or 3.2 to 3.5, or 3.2 to 3.4, as measured by IPC TM-6502.5.59. In various embodiments, the laminate has a peel strength of at least 2.5 Ib / in as measured by IPC-TM-650 2.4.8 (e.g., in the range of 2.5-5 Ib / in, or 2.5-4.5 Ib / in, or 2.5-4 Ib / in, or 3-5 Ib / in, or 3-4.5 Ib / in, or 3-4 Ib / in). In various embodiments, the laminate has a Tg as measured by DSC in the range of 180-270 °C, e.g., 180-260 °C, or 190-270 °C, or 190-260 °C, or 200-270 °C, 200-260 °C, or 210-270 °C, 210-260 °C, or 220- 270 °C, or 220-260 °C.

[0099] Various aspects and embodiments of the disclosure are further provided by the following non-limiting examples.EXAMPLE 1

[0100] Various aspects and embodiments of the disclosure are further provided by the following.

[0101] Phenyl-substituted oligomers as described herein were prepared with varying amounts of monomers as described in the Table below:*nominally 1 ,3-diisopropenylbenzene, but included a minor quantity of 1 ,4- diisopropenylbenzene.

[0102] The phenyl-substituted oligomers described above were included in example formulations as described in the Tables below. The values of the Table are on a solids basis:

[0103] The PPO methacrylate is the poly(phenylene oxide) bismethacrylate available under the trade name NORYL 900, having the nominal structural formula. The styrene-butadiene rubber (70% 1-2 vinyl, 17-27 wt% styrene) is the material available under the trade name RICON® 100. The styrene-butadiene rubber (20-40% 1 ,2-vinyl, 20-30 wt% styrene) is the material available under the trade name RICON® 181. The styrene- butadiene rubber (30% 1 ,2-vinyl), 28% styrene) is the material available under the trade name RICON® 184. The maleimide resin is MIR-3000. The micro particulate silica is DQ- 1028L, available from Novoray. The halogen-free flame retardant is a composition comprising the high melting point isomer of Formula Ila:Formula Ilaand the low melting point isomers of Formula lib and He having the Formulas:Formula libwherein said composition has an Isomer Ratio of greater than about 0.5 utilizing the 31 P NMR method and wherein said Isomer Ratio=Ah / (Ah+Ai), wherein Ah: area of high melting point isomer peak and A area of low melting point isomers peak.

[0104] The thermosetting compositions are formed into 6-ply laminates. The thermosetting composition is charged into a dip pan, and woven glass fabric (2116, low Dk glass, 0.10 mm thick, 105 g / m2) is drawn through the dip pan and then between rollers having 0.012 gap thickness. The resin-coated glass fabric is dried in an oven to substantially remove solvent (i.e. , less than 1% solvent remaining). This provides a prepreg material with 57% resin on glass, about 0.005” in thickness.

[0105] Six layers of this prepreg are plied up between two sheets of copper (BF-NN grade, super flat profile, “1oz,” 35 microns nominal thickness), with the treated side of the copper contacting the prepreg material, and the assembly is then placed between twostainless steel press platens, and loaded into a hot oil vacuum press. Pressure (200-500 psi) and vacuum (2-5 mbar) are applied, and the temperature of the load is brought to the dwell temp (210 °C) at a defined heat rise rate (2.5 °C / min) and held there for a defined time (120 min), after which the press is allowed to cool at about 5°C / min, until the resulting laminate is cool enough to remove.

[0106] Data for two example formulations are provided in the Table below:*Tg determined by DMA

[0107] The use of thin, high-flatness copper is especially challenging from the standpoint of peel strength. The formulations described herein are demonstrated to provide good peel strength, even to BF-NN grade copper.

[0108] Various aspects of the disclosure are illustrated by the following enumerated embodiments, which can be combined in any number and in any combination not technically or logically inconsistent:Embodiment 1. A phenyl-substituted oligomer that is a reaction product of an oligomerization mixture comprising one or more of divinylbenzene and styrene; and one or more of isopropenylbenzene and diisopropenylbenzene,wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues of at least 20%; and the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants of at least 50%.Embodiment 2. The oligomer of embodiment 1, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues of at least 25% (e.g., at least 30%, or at least 35%, or at least 40%).Embodiment 3. The oligomer of embodiment 1, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 20-90% (e.g., in the range of 20-80%, or 20-70%, or 20-60%, or 20-50%).Embodiment 4. The oligomer of embodiment 1, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 30-90% (e.g., in the range of 30-80%, or 30-70%, or 30-60%, or 30-50%, or 30-40%).Embodiment 5. The oligomer of embodiment 1, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 40-90% (e.g., in the range of 40-80%, or 40-70%, or 40-60%, or 40-50%).Embodiment 6. The oligomer of embodiment 1, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 50-90% (e.g., in the range of 50-80%, or 50-70%, or 50-60%).Embodiment 7. The oligomer of embodiment 1, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 60-90% (e.g., in the range of 60-80%, or 60-70%).Embodiment 8. The oligomer of embodiment 1, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 60-90% (e.g., in the range of 60-80%, or 60-70%, or 70-90%, or 70-80%).Embodiment 9. The oligomer of any of embodiments 1-8, wherein the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants of at least 60%, e.g., at least 70%, at least 75%, or at least 80%.Embodiment 10. The oligomer of any of embodiments 1-8, wherein the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 50-98%, e.g., 50-95%, or 50-90%, or 50-85%, or 50- 80%.Embodiment 11. The oligomer of any of embodiments 1-8, wherein the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 60-98%, e.g., 60-95%, or 60-90%, or 60-85%, or 60- 80%.Embodiment 12. The oligomer of any of embodiments 1-8, wherein the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 70-98%, e.g., 70-95%, or 70-90%, or 70-85%, or 70- 80%.Embodiment 13. The oligomer of any of embodiments 1-8, wherein the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 75-98%, e.g., 75-95%, or 75-90%, or 75-85%.Embodiment 14. The oligomer of any of embodiments 1-8, wherein the oligomerization mixture has a ratio of vinyl residues of polyfunctional (e.g., difunctional) reactants to vinyl residues of all reactants in the range of 80-98%, e.g., 80-95%, or 80-90%.Embodiment 15. The oligomer of any of embodiments 1-14, wherein the one or more of divinylbenzene and styrene is present in a range of 10-80 wt% (e.g., 10-70 wt%, or 10-60 wt%, or 10-50 wt%) of polymerizable components of the oligomerization mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-90 wt% (e.g., 30-90 wt%, or 40-90 wt%, or 50-90 wt%) of polymerizable components of the oligomerization mixture.Embodiment 16. The oligomer of any of embodiments 1-14 wherein the one or more of divinylbenzene and styrene is present in a range of 20-80 wt% (e.g., 20-70 wt%, or 20-60 wt%, or 20-50 wt%, or 20-40 wt%) of polymerizable components of the oligomerizable mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-80 wt% (e.g., in the range of 30-80 wt%, or 40-80 wt%, or 50-80 wt%, or 60-80 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 17. The oligomer of any of embodiments 1-14, wherein the one or more of divinylbenzene and styrene is present in a range of 30-80 wt% (e.g., 30-70 wt%, or 30-60 wt%, or 30-50 wt%) of polymerizable components of the oligomerizable mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-70 wt% (e.g., in the range of 30-70 wt%, or 40-70 wt%, or 50-70 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 18. The oligomer of any of embodiments 1-14, wherein the one or more of divinylbenzene and styrene is present in a range of 40-80 wt% (e.g., 40-70 wt%, or 40-60 wt%) of polymerizable components of the oligomerizable mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-60 wt% (e.g., in the range of 30-60 wt%, or 40-60 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 19. The oligomer of any of embodiments 1-18, wherein a molar ratio of one or more of divinylbenzene and styrene to one or more of isopropenylbenzene and diisopropenylbenzene in the oligomerizable mixture is at least 0.2:1 (e.g., at least 0.35:1, at least 0.5:1 , at least 0.75:1).Embodiment 20. The oligomer of any of embodiments 1-19, wherein a molar ratio of one or more of divinylbenzene and styrene to one or more of isopropenylbenzene and diisopropenylbenzene in the oligomerizable mixture is no more than 2:1 (e.g., no more than 1.5:1 , or no more than 1.2:1, or no more than 1:1).Embodiment 21. The oligomer of any of embodiments 1-18, wherein a molar ratio of one or more of divinylbenzene and styrene to one or more of isopropenylbenzene and diisopropenylbenzene is in the range of 0.2:1 to 2:1 (e.g., in the range of 0.2:1 to 1.5:1, or 0.2:1 to 1.2:1, or 0.2:1 to 1:1 , or 0.35:1 to 2:1, or 0.35:1 to 1.5:1, or 0.35:1 to 1.2:1 , or 0.35:1 to 1:1 , or 0.5:1 to 2:1 , or 0.5:1 to 1.5:1 , or 0.5:1 to 1.2:1, or 0.5:1 to 1:1 , or 0.75:1 to 2:1 , or 0.75:1 to 1.5:1 , or 0.75:1 to 1.2:1 , or 0.75:1 to 1:1).Embodiment 22. The oligomer of any of embodiments 1-21, wherein the divinylbenzene is present in a range of 2-50 wt% (e.g., in the range of 2-30 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 23. The oligomer of any of embodiments 1-21, wherein the divinylbenzene is present in a range of 10-50 wt% (e.g., in the range of 10-30 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 24. The oligomer of any of embodiments 1-21, wherein the divinylbenzene is present in a range of 15-50 wt% (e.g., in the range of 15-40 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 25. The oligomer of any of embodiments 1-24, wherein the styrene is present in a range of 10-50 wt% (e.g., in the range of 10-40 wt%, or 10-30 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 26. The oligomer of any of embodiments 1-24, wherein the styrene is present in a range of 15-50 wt% (e.g., in the range of 15-40 wt%, or 15-35 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 27. The oligomer of any of embodiments 1-24, wherein the styrene is present in a range of 20-50 wt% (e.g., in the range of 20-40 wt%, or 25-40 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 28. The oligomer of any of embodiments 1-27, wherein the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 20-90 wt% (e.g., in the range of 20-80 wt%, or 20-70 wt%, or 20-60 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 29. The oligomer of any of embodiments 1-27, wherein the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 30-90 wt% (e.g., in the range of 30-80 wt%, or 30-70 wt%, or 30-60 wt%) of polymerizable components of the oligomerization mixture.Embodiment 30. The oligomer of any of embodiments 1-27, wherein the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 40-90 wt% (e.g., in the range of 40-80 wt%, or 40-70 wt%, or 40-60 wt%) of polymerizable components of the oligomerization mixture.Embodiment 31. The oligomer of any of embodiments 1-30, wherein the diisopropenylbenzene is present in a range of 20-90 wt% (e.g., in the range of 20-80 wt%, or 20-70 wt%, or 20-60 wt%) of polymerizable components of the oligomerizable mixture.Embodiment 32. The oligomer of any of embodiments 1-30, wherein the diisopropenylbenzene is present in a range of 30-90 wt% (e.g., in the range of 30-80 wt%, or 30-70 wt%, or 30-60 wt%) of polymerizable components of the oligomerization mixture.Embodiment 33. The oligomer of any of embodiments 1-30, wherein the diisopropenylbenzene is present in a range of 40-90 wt% (e.g., in the range of 40-80 wt%, or 40-70 wt%, or 40-60 wt%) of polymerizable components of the oligomerization mixture.Embodiment 34. The oligomer of any of embodiments 1-33, wherein the oligomerization mixture comprises divinylbenzene and styrene with one or more of isopropenylbenzene and diisopropenylbenzene.Embodiment 35. The oligomer of any of embodiments 1-33, wherein the oligomerization mixture comprises divinylbenzene, styrene and diisopropenylbenzene.Embodiment 36. The oligomer of any of embodiments 1-35, wherein the total amount of styrene, divinylbenzene, isopropenylbenzene and diisopropenylbenzene is at least 90 wt% of polymerizable components of the oligomerization mixture, e.g., at least 95 wt%, at least 98 wt% or at least 99 wt%.Embodiment 37. The oligomer of any of embodiments 1-36, wherein the oligomerizable reaction mixture has no more than 5 wt% of heteroatom-containing polymerizable components, e.g., no more than 2 wt%, no more than 1 wt%, or no more than 0.5 wt%.Embodiment 38. The oligomer of any of embodiments 1-37, wherein the divinylbenzene is one or more of 1,4-divinylbenzene and 1,3-divinylbenzene (e.g., is 1,4-divinylbenzene), and / or the diisopropenylbenzene is one or more of 1 ,3-diisopropenylbenzene and 1,4- diisopropenylbenzene (e.g., is 1,3-diisopropenylbenzene).Embodiment 39. The oligomer of any of embodiments 1-38, having a weight-average molecular weight in the range of 1000 to 15000 g / mol (e.g., in the range of 1000 to 12000 g / mol, or 1000 to 10000 g / mol, or 1000 to 8000 g / mol, or 1500 to 15000 g / mol, or 1500 to12000 g / mol, or 1500 to 10000 g / mol, or 1500 to 8000 g / mol, or 2000 to 15000 g / mol, or 2000 to 12000 g / mol, or 2000 to 10000 g / mol, or 2000 to 8000 g / mol).Embodiment 40. The oligomer of any of embodiments 1-39, wherein the polymerizable mixture includes a free-radical initiator, and the oligomer is a free-radical-polymerized oligomer.Embodiment 41. The oligomer of embodiment 40, wherein the polymerizable mixture includes a chain transfer catalyst, e.g., a cobalt chain transfer catalyst such as (H2O)2Co(dmgBF2)2, and the oligomer is a catalytic chain transfer polymerized oligomer.Embodiment 42. The polymerization reaction product of a polymerizable composition comprising the phenyl-substituted oligomer of any of embodiments 1-41, for example, wherein the polymerizable composition includes at least 5 wt% of the phenyl-substituted oligomer, e.g., at least 10 wt%, or at least 20 wt%, or at least 30 wt%.Embodiment 43. A thermosetting composition comprising one or more free-radical polymerizable components, the one or more free-radical polymerizable components including the oligomer of any of embodiments 1-41 , present in the composition an amount in the range of 1-69 wt% on a dry solids basis; microparticulate silica, in an amount in the range of 15-50 wt% on a dry solids basis; an organic halogen-free fire retardant component, in an amount of 15-35 wt% on a dry solids basis; and an effective amount of a thermal free-radical initiator component (e.g., 0.1-4 wt% on a dry solids basis).Embodiment 44. The thermosetting composition of embodiment 43, wherein the oligomer is present in an amount in the range of 1-50 wt% (e.g., in the range of 1-40 wt%, or 1-35 wt%, or 1-30 wt%, or 1-25 wt%) on a dry solids basis.Embodiment 45. The thermosetting composition of embodiment 43, wherein the oligomer is present in an amount in the range of 2-69 wt%, e.g., 2-50 wt%, or 2-40 wt%, or 2-35 wt%, or 2-30 wt%, or 2-25 wt%, on a dry solids basis.Embodiment 46. The thermosetting composition of embodiment 43, wherein the oligomer is present in an amount in the range of 5-69 wt%, e.g., 5-50 wt%, or 5-40 wt%, or 5-35 wt%, or 5-30 wt%, or 5-25 wt%, on a dry solids basis.Embodiment 47. The thermosetting composition of embodiment 43, wherein the oligomer is present in an amount in the range of 10-69 wt%, e.g., 10-50 wt%, or 10-40 wt%, or 10-35 wt%, or 10-30 wt%, or 10-25 wt%, on a dry solids basis.Embodiment 48. The thermosetting composition of any of embodiments 43-47, wherein the one or more polymerizable components further comprises a poly(1,4-phenylene ether) component having at least 80% phenylene ether content, the poly(1,4-phenylene ether) component being a poly(1,4-phenylene ether) bis(meth)acrylate component, a bis(vinyl) poly(1,4-phenylene ether) component, or a bis((meth)allyl) poly(1 ,4-phenylene ether) component, or a combination of two or more thereof, in an amount in the range of 5-35 wt% on a dry solids basis;Embodiment 49. The thermosetting composition of embodiment 48, wherein the mass of the (optionally-substituted phenylene) groups of the -©-(optionally-substituted phenylene) content of the poly ( 1 ,4-phenylene ether) component is made up of at least 50% phenyl carbons and phenyl hydrogens.Embodiment 50. The thermosetting composition of embodiment 48 or embodiment 49, wherein the poly(1,4-phenylene ether) component is a poly(1 ,4-phenylene ether) bismethacrylate component, i.e., having at least 75 wt%, e.g., at least 90 wt% poly(1 ,4- phenylene ether) bismethacrylate.Embodiment 51. The thermosetting composition of any of embodiments 48-50, wherein the poly(1 ,4-phenylene ether) component is a bis(vinyl) poly(1 ,4-phenylene ether) component, i.e., having at least 75 wt%, e.g., at least 90 wt% bis(vinyl) poly(1,4-phenylene ether).Embodiment 52. The thermosetting composition of any of embodiments 48-51 , wherein the poly(1 ,4-phenylene ether) component is a bis(allyl) poly(1,4-phenylene ether) component, i.e., having at least 75 wt%, e.g., at least 90 wt% bis(allyl) poly(1 ,4-phenylene ether).Embodiment 53. The thermosetting composition of any of embodiments 48-52, wherein the poly(1 ,4-phenylene ether) component is a bis(methallyl) poly(1 ,4-phenylene ether)component, i.e., having at least 75 wt%, e.g., at least 90 wt% bis(methallyl) poly(1 ,4- phenylene ether).Embodiment 54. The thermosetting composition of any of embodiments 48-53, wherein the poly(1 ,4-phenylene ether) component has the formulawherein A is a bond, -CH2-, CH(CH3)-, -C(CH3)2-, -O-, -C(O)-, S(O), or S(O)2; each R1is independently methacrylate, acrylate, vinyl, allyl or methallyl; each R2is independently methyl or hydrogen; and each R3is independently methyl or hydrogen.Embodiment 55. The thermosetting composition of embodiment 54, wherein A is -CH2-, CH(CH3)- or -C(CH3)2-.Embodiment 56. The thermosetting composition of embodiment 54, wherein A is -C(CH3)2-.Embodiment 57. The thermosetting composition of any of embodiments 54-56, wherein in atmoieties (e.g., at least 90% or at least 98%), two R2are methyl and two R2 are H.Embodiment 58. The thermosetting composition of any of embodiments 54-56, wherein in atmoieties (e.g., at least 90% or at least 98%), two R2are methyl substituted in a meta relationship and two R2are H.Embodiment 59. The thermosetting composition of any of embodiments 54-56, wherein in at least 75% of themoieties (e.g., at least 90% or at least 98%), two R2are methyl substituted in a meta relationship distal to the A moiety, and two R2are H.Embodiment 60. The thermosetting composition of any of embodiments 54-59, wherein in at least 75% of themoieties (e.g., at least 90% or at least 98%), two R3are methyl and two R3are H.Embodiment 61. The thermosetting composition of any of embodiments 54-60, wherein in at least 75% of themoieties (e.g., at least 90% or at least 98%), two R3are methyl substituted in a meta relationship and two R3are H.Embodiment 62. The thermosetting composition of any of embodiments 54-60, wherein in at least 75% of themoieties (e.g., at least 90% or at least 98%), two R3are methyl substituted in a meta relationship distal to the A moiety, and two R3are H.Embodiment 63. The thermosetting composition of any of embodiments 54-62, wherein at least 75% of R1are methacrylate, e.g., at least 90%, or at least 95%.Embodiment 64. The thermosetting composition of any of embodiments 54-62, wherein at least 75% of R1are vinyl, e.g., at least 90%, or at least 95%.Embodiment 65. The thermosetting composition of any of embodiments 54-62, wherein at least 75% of R1are allyl, e.g., at least 90%, or at least 95%.Embodiment 66. The thermosetting composition of any of embodiments 54-62, wherein at least 75% of R1are methallyl, e.g., at least 90%, or at least 95%.Embodiment 67. The thermosetting composition of any of embodiments 52-64, wherein at least 75% of R1are methacrylate, vinyl, allyl or methallyl, e.g., at least 90%, or at least 95%.Embodiment 68. The thermosetting composition of any of embodiments 48-67 wherein at least 75 wt%, e.g., at least 90 wt% or at least 95 wt%, of the poly(1 ,4-phenylene ether) component has the formulaEmbodiment 69. The thermosetting composition of embodiment 68, wherein the poly(1 ,4- phenylene ether) component has a number-average value of the sum of x+y in the range of 3-30, e.g., 3-25, or 3-20, or 3-15, or 5-30, or 5-25, or 5-20, or 5-15, or 7-30, or 7-25, or 7-20, or 7-15, or 10-30, or 10-25, or 10-20, or 10-15.Embodiment 70. The thermosetting composition of any of embodiments 48-69, wherein the poly(1 ,4-phenylene ether) component has a number-average molecular weight in the range of 1000-4000 g / mol, e.g., 1000-3500 g / mol or 1000-3000 g / mol, or 1000-2500 g / mol, or 1500-4000 g / mol, or 1500-3500 g / mol, or 1500-2500 g / mol.Embodiment 71 . The thermosetting composition of any of embodiments 48-70, wherein the poly(1 ,4-phenylene ether) component is present in an amount of 5-50 wt%, e.g., 5-30 wt%, or 5-25 wt%, or 5-20 wt%, on a dry solids basis.Embodiment 72. The thermosetting composition of any of embodiments 48-70, wherein the poly(1 ,4-phenylene ether) component is present in an amount of 10-50 wt%, e.g., 10-30 wt%, or 10-25 wt%, or 10-20 wt%, on a dry solids basis.Embodiment 73. The thermosetting composition according to any of embodiments 43-90, wherein the one or more free-radical polymerizable components further comprises an aromatic crosslinking component having a weight average molecular weight of no greater than 700 g / mol and bearing on numerical average in the range of 1.75 - 3.5 crosslinkable vinyl, (meth)allyl and / or (meth)acrylate groups per molecule, in an amount up to 10 wt%, on a dry solids basis.Embodiment 74. The thermosetting composition of embodiment 73, wherein the aromatic crosslinking component includes (or is) a cyanurate component.Embodiment 75. The thermosetting composition of embodiment 73, wherein the aromatic crosslinking component is a cyanurate component that is triallylcyanurate, triallylisocanurate, or a combination of triallylcyanurate and triallylisocanurate.Embodiment 76. The thermosetting composition of any of embodiments 73-75, wherein the aromatic crosslinking component includes (or is) triallylcyanurate.Embodiment 77. The thermosetting composition of any of embodiments 73-76, wherein the aromatic crosslinking component includes (or is) triallylisocyanurate.Embodiment 78. The thermosetting composition of any of embodiments 73-77, wherein the aromatic crosslinking component includes (or is) a combination of triallylcyanurate and triallylisocanurate.Embodiment 79. The thermosetting composition of any of embodiments 73-78, wherein the aromatic crosslinking component includes (or is) trimethallylisocyanurate.Embodiment 80. The thermosetting composition of any of embodiments 73-79 wherein the aromatic crosslinking component includes (or is) a divinylbenzene.Embodiment 81. The thermosetting composition of embodiment 73, wherein the aromatic crosslinking component includes (or is) triallylcyanurate, triallylisocyanurate, trimethallylisocyanurate, divinylbenzene. or any combination thereof.Embodiment 82. The thermosetting composition of any of embodiments 73-81, wherein the aromatic crosslinking component is present in an amount in the range of 0-8 wt%, e.g., 0-6 wt%, on a dry solids basis.Embodiment 83. The thermosetting composition of any of embodiments 73-81, wherein the aromatic crosslinking component is present in an amount in the range of 2-10 wt%, e.g., 2-8 wt%, or 2-6 wt%, on a dry solids basis.Embodiment 84. The thermosetting composition of any of embodiments 73-81, wherein the aromatic crosslinking component is present in an amount in the range of 3-10 wt%, e.g., 3-8 wt%, or 3-6 wt%, on a dry solids basis.Embodiment 85. The thermosetting composition of any of embodiments 43-84, wherein the one or more free-radical polymerizable components further comprises a butadiene / styrene copolymeric rubber component, in an amount of 5-25 wt%.Embodiment 86. The thermosetting composition of embodiment 85, wherein the butadiene / styrene copolymeric rubber component has a total content of butadiene and styrene residues in an amount of at least 90 wt%, e.g., at least 95 wt%, at least 97 wt%, at least 98 wt%, or at least 99 wt%.Embodiment 87. The thermosetting composition of embodiment 85 or embodiment 86, wherein the butadiene / styrene copolymeric rubber component comprises up to 5 wt% divinylbenzene residues, e.g., in the range of 0.5-5 wt%, or 0.5-3 wt%, or 1-5 wt%, or 1-3 wt%.Embodiment 88. The thermosetting composition of any of embodiments 85-87, wherein the butadiene / styrene copolymeric rubber component has a substantially random arrangement of butadiene and styrene.Embodiment 89. The thermosetting composition of any of embodiments 85-88, wherein the butadiene / styrene copolymeric rubber component has a number average molecular weight in the range of 1500-7000 g / mol, e.g., 1500-5000 g / mol, or 2500-7000 g / mol, or 2500-5000 g / mol.Embodiment 90. The thermosetting composition of any of embodiments 85-89, wherein the butadiene residues of the butadiene / styrene copolymeric rubber component have a molar fraction of 1 ,2-vinyl moieties in the range of 15-80 mol%, e.g., 15-70%, or 15-60%, or 20-80 mol%, or 20-70 mol%.Embodiment 91. The thermosetting composition of any of embodiments 85-90, wherein the butadiene residues of the butadiene / styrene copolymeric rubber component have a molar fraction of 1 ,2-vinyl moieties of 25-80 mol%, e.g., 25-70%, or 25-60%, or 30-80 mol%, or 30- 70 mol%.Embodiment 92. The thermosetting composition of any of embodiments 85-90, wherein the butadiene residues of the butadiene / styrene copolymeric rubber component have a molar fraction of 1 ,2-vinyl moieties of 20-60 mol%, e.g., 20-55 mol%, or 20-50 mol%, or 20-45 mol%, or 25-60 mol%, or 25-55 mol%, or 25-50 mol%, or 25-45 mol%, or 30-60 mol%, or SO- 55 mol%, or 30-50 mol%, or 30-45 mol%, or 35-60 mol%, or 35-55 mol%, or 35-50 mol%, or 35-45 mol%.Embodiment 93. The thermosetting composition of any of embodiments 85-92, wherein the butadiene / styrene copolymeric rubber component has in the range of 15-40 wt% styrene residues, e.g., 15-35 wt% or 15-30 wt%.Embodiment 94. The thermosetting composition of any of embodiments 85-92, wherein the butadiene / styrene copolymeric rubber component has in the range of 20-40 wt% styrene residues, e.g., 20-35 wt% or 20-30 wt%.Embodiment 95. The thermosetting composition of any of embodiments 85-92, wherein the butadiene / styrene copolymeric rubber component has in the range of 23-40 wt% styrene residues, e.g., 23-35 wt% or 23-30 wt%.Embodiment 96. The thermosetting composition of any of embodiments 85-95, wherein the butadiene / styrene copolymeric rubber component is made up of a first butadiene / styrene substantially random copolymeric rubber subcomponent that has 17-27 wt% styrene residues and in which the butadiene residues have a molar fraction of 1 ,2-vinyl moieties of 60-80 mol%; and a second butadiene / styrene substantially random copolymeric rubber subcomponent that has 20-30 wt% styrene residues and in which the butadiene residues have a molar fraction of 1 ,2-vinyl moieties of 20-40 mol%.Embodiment 97. The thermosetting composition of embodiment 96, wherein a weight ratio of the first butadiene / styrene substantially random copolymeric rubber subcomponent and the second butadiene / styrene substantially random copolymeric rubber subcomponent is in the range of 1 :1.2 - 1 :2.3, e.g., 1 :1.5 - 1 :2.3, or 1 :1.2 - 1 :2, or 1 :1.5 - 1 :2.Embodiment 98. The thermosetting composition of any of embodiments 85-97, wherein the butadiene / styrene copolymeric rubber component is present in an amount in the range of 5- 20 wt%, or 5-18 wt%, or 5-15 wt%, on a dry solids basis.Embodiment 99. The thermosetting composition of any of embodiments 85-97, wherein the butadiene / styrene copolymeric rubber component is present in an amount in the range of 7- 25 wt%, e.g., 7-20 wt%, or 7-18 wt%, or 7-15 wt%, on a dry solids basis.Embodiment 100. The thermosetting composition of any of embodiments 85-97, wherein the butadiene / styrene copolymeric rubber component is present in an amount in the range of 9-25 wt%, e.g., 9-20 wt%, or 9-18 wt%, or 9-15 wt%, on a dry solids basis.Embodiment 101 . The thermosetting composition of any of embodiments 43-100, wherein the one or more free-radical polymerizable components further comprises a maleimide resin, in an amount of 1-10wt%.Embodiment 102. The thermosetting composition of embodiment 101 , wherein the maleimide resin is present in an amount in the range of 1-8 wt%, e.g., 1-6 wt%.Embodiment 103. The thermosetting composition of embodiment 101 , wherein the maleimide resin is present in an amount in the range of 2-10 wt%, e.g., 2-8 wt%, or 2-6 wt%.Embodiment 104. The thermosetting composition of embodiment 101 , wherein the maleimide resin is present in an amount in the range of 3-10 wt%, e.g., 3-8 wt%, or 3-6 wt%.Embodiment 105. The thermosetting composition of any of embodiments 43-104, wherein the micro particulate silica has a dso particle size in the range of 0.5-10 microns, e.g., 0.5-7 microns, or 0.5-5 microns, or 1-10 microns, or 1-7 microns, or 1-5 microns.Embodiment 106. The thermosetting composition of any of embodiments 43-104, wherein the microparticulate silica has a dgo particle size in the range of 1-20 microns, e.g., 1-14 microns, or 1-8 microns, or 3-20 microns, or 3-14 microns, or 3-8 microns.Embodiment 107. The thermosetting composition of any of embodiments 43-106, wherein the microparticulate silica has a d particle size in the range of 0.1-5 microns, e.g., 0.1-3 microns, or 0.1-2 microns, or 0.5-5 microns, or 0.5-3 microns, or 0.5-2 microns.Embodiment 108. The thermosetting composition of any of embodiments 43-107, wherein the microparticulate silica is substantially spherical.Embodiment 109. The thermosetting composition of any of embodiments 43-108, wherein the microparticulate silica has at least 99 wt% SiC>2, e.g., at least 99.5 wt% SiC>2-Embodiment 110. The thermosetting composition of any of embodiments 43-109, wherein the microparticulate silica is present in an amount in the range of 15-45 wt%, or 15-40 wt%, or 15-35 wt% on a dry solids basis.Embodiment 111. The thermosetting composition of any of embodiments 43-109, wherein the microparticulate silica is present in an amount in the range of 20-50 wt%, e.g., 20-45 wt%, or 20-40 wt%, or 20-35 wt% on a dry solids basis.Embodiment 112. The thermosetting composition of any of embodiments 43-109, wherein the microparticulate silica is present in an amount in the range of 20-50 wt%, e.g., 25-45 wt%, or 25-40 wt%, or 25-35 wt% on a dry solids basisEmbodiment 113. The thermosetting composition of any of embodiments 43-112, wherein the organic halogen-free fire-retardant component is a fire retardant as described in any of U.S. Patents nos. 8536256, 9012546, 9522927 and 9562063.Embodiment 114. The thermosetting composition of any of embodiments 43-112, wherein the organic halogen-free fire retardant component includes (or is) 6H- Dibenz[c,e][1,2]oxaphosphorine, 6,6'-(1 ,4-ethanediyl)bis-, 6,6'-dioxide; 6H- Dibenz[c,e][1 ,2]oxaphosphorine, 6,6'-(1 ,4-butanediyl)bis-,6,6'-dioxide; or 6H- Dibenz[c,e][1,2]oxaphosphorine, 6,6'-(p-xylenediyl)bis-,6,6'-dioxide; or any combination thereof.Embodiment 115. The thermosetting composition of any of embodiments 43-112, wherein the organic halogen-free fire retardant component includes (or is) is 6H- Dibenz[c,e][1 ,2]oxaphosphorin, 6,6'-(1 ,4-ethanediyl)bis-, 6,6'-dioxide.Embodiment 116. The thermosetting composition of any of embodiments 43-112, wherein the organic halogen-free fire retardant component includes (or is) a compound having the structure: having the following structure:Embodiment 117. The thermosetting composition of any of embodiments 43-112, wherein the organic halogen-free fire retardant component includes (or is) composition comprising the high melting point isomer of Formula Ila:Formula Ilaand the low melting point isomers of Formula lib and He having the Formulas:Formula libwherein said composition has an Isomer Ratio of greater than about 0.5 utilizing the 31 P NMR method and wherein said Isomer Ratio=Ah / (Ah+Ai), wherein Ah: area of high melting point isomer peak and A area of low melting point isomers peak.Embodiment 118. The thermosetting composition according to any of embodiments 43-117, wherein the organic halogen-free fire retardant component is present in an amount of 15-30 wt%, e.g., 15-25 wt% on a dry solids basis.Embodiment 119. The thermosetting composition according to any of embodiments 43-117, wherein the organic halogen-free fire retardant component is present in an amount of 20-35 wt%, e.g., 20-30 wt%, or 20-25 wt% on a dry solids basis.Embodiment 120. The thermosetting composition according to any of embodiments 43-117, wherein the organic halogen-free fire retardant component is present in an amount of 25-35 wt%, e.g., 25-30 wt% on a dry solids basis.Embodiment 121. The thermosetting composition according to any of embodiments 43-120, wherein the thermal free-radical initiator component is one or more of benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, lauryl peroxide, cyclohexanone peroxide, t- butyl hydroperoxide, t-butyl benzene hydroperoxide, acetyl isobutyryl peroxide, diacetyl peroxide, t-butyl peroctoate, a,a'-bis(t-butylperoxy-m-isopropyl)benzene, 2,3-dimethyl-2,3- diphenylbutane, di(trimethylsilyl)peroxide, ,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t- butylperoxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylperoxy benzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2trimethylsilylphenyltriphenylsilyl peroxide, 2,3-trimethylsilyloxy-2,3-diphenylbutane, di(t- butylperoxy) isophthalate, azobisisobutyronitrile (Al BN), azobis(2-isopropyl)butyronitrile, 2,2'- azobis(2,4-dimethyl)valeronitrile (AVBN), (2,4-dichlorobenzoyl) peroxide, (2- dimethylbenzoyl) peroxide, and dodecanoyl peroxide.Embodiment 122. The thermosetting composition according to any of embodiments 43-121 , wherein the thermal free-radical initiator component is present in an amount in the range of 0.05-4 wt%, e.g., 0.05-2 wt%, or 0.05-1 wt%, or 0.05-0.7 wt%, on a dry solids basis.Embodiment 123. The thermosetting composition according to any of embodiments 43-121 , wherein the thermal free-radical initiator component is present in an amount in the range of 0.07-4 wt%, e.g., 0.07-2 wt%, or 0.07-1 wt%, or 0.07-0.7 wt%, on a dry solids basis.Embodiment 124. The thermosetting composition according to any of embodiments 43-121 , wherein the thermal free-radical initiator component is present in an amount in the range of 0.1-4 wt%, e.g., 0.1-2 wt%, or 0.1-1 wt%, or 0.1-0.7 wt%, on a dry solids basis.Embodiment 125. The thermosetting composition according to any of embodiments 43-121 , wherein the thermal free-radical initiator component is present in an amount in the range of 0.2-4 wt%, e.g., 0.2-2 wt%, or 0.2-1 wt%, or 0.2-0.7 wt%.Embodiment 126. The thermosetting composition according to any of embodiments 43-125, further comprising a silane coupling agent, e.g., in an amount up to 5 wt% on a dry solids basis.Embodiment 127. The thermosetting composition according to any of embodiments 43-125, comprising no more than 0.01 wt% of a silane coupling agent on a dry solids basis.Embodiment 128. The thermosetting composition according to any of embodiments 43-127, provided in substantially non-volatile form, i.e. , without a substantial amount of a solvent.Embodiment 129. The thermosetting composition according to any of embodiments 43-127, comprising no more than 10 wt% material having a boiling point at atmospheric pressure ofless than 200 °C, e.g., no more than 5 wt%, or no more than 3 wt%, or no more than 1 wt%, all calculated with the non-volatile content being 100 wt%.Embodiment 130. The thermosetting composition according to any of embodiments 43-127, further comprising a solvent having a boiling point at atmospheric pressure of less than 200 °C.Embodiment 131. The thermosetting composition according to embodiment 130, wherein the solvent is one or more of y-butyrolactone, cyclohexanone, butanone, methyl isobutyl ketone, N,N-dimethylformamide, propylene glycol monomethyl ether, N,N- dimethylacetamide, ethylene glycol monomethyl ether, methoxy ethyl acetate, ethoxy ethyl acetate, propoxy ethyl acetate, diisobutyl ketone (DIBK), N-methyl-pyrrolidone., xylene, ethyl acetate, toluene, trichloroethane, dibutyl ether, methyl ethyl ketone, and acetone.Embodiment 132. The thermosetting composition according to embodiment 130 or embodiment 131, wherein an amount of solvent is in the range of 20-60 wt% in excess of the non-volatile components of the thermosetting composition (i.e. , taken together as 100 wt%).Embodiment 133. A cured product of a thermosetting composition according to any of embodiments 43-132.Embodiment 134. A method for curing the thermosetting composition according to any of embodiments 43-132, comprising heating the thermosetting composition at a temperature of 150-250 °C.Embodiment 135. A prepreg comprising a mesh substrate at least partially embedded in a cured product of embodiment 133 or a cured product made by the method of embodiment 134.Embodiment 136. The prepreg according to embodiment 135, wherein the cured product is a partially-cured product.Embodiment 137. The prepreg according to embodiment 135 or embodiment 136, wherein, the mesh substrate is a fabric (woven or non-woven).Embodiment 138. The prepreg according to embodiment 137, wherein the fabric made from glass fiber, e.g., as a borosilicate glass fabric.Embodiment 139. The prepreg according to embodiment 135 or embodiment 136, wherein, the mesh substrate is electronic grade E-glass fabric, NE-glass fabric, D-glass fabric, or S- glass fabric.Embodiment 140. The prepreg according to any of embodiments 135-139. that is in the range of 10-300 microns in thickness, e.g., 10-200 microns, or 10-150 microns, or 10-100 microns.Embodiment 141. The prepreg according to any of embodiments 135-139, that is in the range of 25-300 microns in thickness, e.g., 25-200 microns, or 25-150 microns, or 25-100 microns.Embodiment 142. The prepreg according to any of embodiments 135-139, that is in the range of 50-300 microns in thickness, e.g., 50-200 microns, or 50-150 microns.Embodiment 143. The prepreg according to any of embodiments 135-142, comprising at least 30 wt% of the cured product of the disclosure, e.g., at least 50 wt%.Embodiment 144. A laminate of a plurality of prepregs according to any of embodiments 135-143.Embodiment 145. A laminate according to embodiment 144, wherein the cured product of the prepregs in the laminate is substantially fully cured.Embodiment 146. A laminate according to embodiment 144 or embodiment 145, further comprising one or more layers of metal, e.g., at one or more opposing major surfaces of the laminate.Embodiment 147. A laminate according to embodiment 146, wherein the one or more layers of metal are layers of copper.Embodiment 148. A laminate according to embodiment 147, wherein the one or more layers of copper are in the range of 15-50 microns in thickness, e.g., in the range of 17-37 microns in thickness.Embodiment 149. A laminate according to any of embodiments 146-148, having a Df value of in the range of 0.0010 to 0.003, e.g., 0.0010 to 0.0025, or 0.0010 to 0.0020, as measured by I PC-TM-6502.5.59.Embodiment 150. A laminate according to any of embodiments 146-148, having a Df value of in the range of 0.0012 to 0.003, e.g., 0.0012 to 0.0025, or 0.0012 to 0.0020, as measured by I PC-TM-6502.5.59.Embodiment 151. A laminate according to any of embodiments 146-150, having a Dk value in the range of 3.0 to 3.5, e.g., in the range of 3.0 to 3.4, or 3.2 to 3.5, or 3.2 to 3.4, as measured by IPC TM-6502.5.59.Embodiment 152. A laminate according to any of embodiments 146-151 , having a Tg as measured by DSC in the range of 180-270 °C, e.g., 180-260 °C, or 190-270 °C, or 190-260 °C, or 200-270 °C, 200-260 °C, or 210-270 °C, 210-260 °C, or 220-270 °C, or 220-260 °C.

Claims

Claims1. A phenyl-substituted oligomer that is a reaction product of an oligomerization mixture comprising one or more of divinylbenzene and styrene; and one or more of isopropenylbenzene and diisopropenylbenzene, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues of at least 20%; and the oligomerization mixture has a ratio of vinyl residues of polyfunctional reactants to vinyl residues of all reactants of at least 50%.

2. The oligomer of claim 1, wherein the oligomer has a ratio of number of methyl-substituted vinyl residues to total number of vinyl residues in the range of 40-80%.

3. The oligomer of claim 1 , wherein the oligomerization mixture has a ratio of vinyl residues of polyfunctional reactants to vinyl residues of all reactants in the range of 70-90%.

4. The oligomer of claim 1 , wherein the one or more of divinylbenzene and styrene is present in a range of 30-70 wt% of polymerizable components of the oligomerizable mixture and the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 30-70 wt% of polymerizable components of the oligomerizable mixture.

5. The oligomer of claim 1 , wherein a molar ratio of one or more of divinylbenzene and styrene to one or more of isopropenylbenzene and diisopropenylbenzene is in the range of 0.5:1 to 2:1 .

6. The oligomer of claim 1 , wherein the divinylbenzene is present in a range of 2-50 wt% of polymerizable components of the oligomerizable mixture.

7. The oligomer of claim 1 , wherein the styrene is present in a range of 15-50 wt% of polymerizable components of the oligomerizable mixture.

8. The oligomer of claim 1 , wherein the one or more of isopropenylbenzene and diisopropenylbenzene is present in a range of 30-80 wt% of polymerizable components of the oligomerization mixture.

9. The oligomer of claim 1 , wherein the oligomerization mixture comprises divinylbenzene and styrene with one or more of isopropenylbenzene and diisopropenylbenzene.

10. The oligomer of claim 1 , wherein the oligomerization mixture comprises divinylbenzene, styrene and diisopropenylbenzene.11 . The oligomer of claim 1 , wherein the total amount of styrene, divinylbenzene, isopropenylbenzene and diisopropenylbenzene is at least 90 wt% of polymerizable components of the oligomerization mixture.

12. The oligomer of claim 1 , wherein the oligomerizable reaction mixture has no more than 5 wt% of heteroatom-containing polymerizable components, e.g., no more than 2 wt%, no more than 1 wt%, or no more than 0.5 wt%.

13. The oligomer of claim 1 , having a weight-average molecular weight in the range of 1000 to 15000 g / mol.

14. The oligomer of claim 1 , wherein the polymerizable mixture includes a free-radical initiator, and the oligomer is a free-radical-polymerized oligomer.

15. The polymerization reaction product of a polymerizable composition comprising the phenyl-substituted oligomer of claim 1.

16. A thermosetting composition comprising one or more free-radical polymerizable components, the one or more free-radical polymerizable components including the oligomer of claim 1 , present in the composition an amount in the range of 1-69 wt% on a dry solids basis; micro particulate silica, in an amount in the range of 15-50 wt% on a dry solids basis; an organic halogen-free fire retardant component, in an amount of 15-35 wt% on a dry solids basis; and an effective amount of a thermal free-radical initiator component.

17. A cured product of a thermosetting composition according to claim 16.

18. A method for curing the thermosetting composition according to claim 16, comprising heating the thermosetting composition at a temperature of 150-250 °C.

19. A prepreg comprising a mesh substrate at least partially embedded in a cured product of claim 17 or a cured product made by the method of claim 18.

20. A laminate of a plurality of prepregs according to claim 19.

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