Rare Earth Metal-Mediated Precision Polymerization of Vinylphosphonates and Conjugated Nitrogen-Containing Vinyl Monomers.

This review focuses on introducing and explaining the rare earth metal-mediated group transfer polymerization (REM-GTP) of polar monomers and is composed of three main sections: poly(vinylphosphonate)s, surface-initiated group transfer polymerization (SI-GTP), and extension to N-coordinating Michael-type monomers (2-vinylpridine (2VP), 2-isopropenyl-2-oxazoline (IPOx)). The poly(vinylphosphonate)s section is divided into two parts: radical, anionic, and silyl ketene acetal group transfer polymerization (SKA-GTP) of vinylphosphonates in comparison to REM-GTP, and properties of poly(vinylphosphonate)s. The mechanism of vinylphosphonate REM-GTP is discussed in detail for initiation and propagation including activation enthalpies ΔH(‡) and entropies ΔS(‡) according to the Eyring equation.

Mechanistic studies on initiation and propagation of rare earth metal-mediated group transfer polymerization of vinylphosphonates.

Initiation of rare earth metal-mediated vinylphosphonate polymerization with unbridged rare earth metallocenes (Cp2LnX) follows a complex reaction pathway. Depending on the nature of X, initiation can proceed either via abstraction of the acidic α-CH of the vinylphosphonate (e.g.

Rare earth metal-mediated group-transfer polymerization: from defined polymer microstructures to high-precision nano-scaled objects.

Poly(2-isopropenyl-2-oxazoline) (PIPOx) and poly(2-vinylpyridine) (P2VP) have been efficiently synthesized using bis(cyclopentadienyl)methylytterbium (Cp2YbMe) as catalyst. The polymerizations of 2-isopropenyl-2-oxazoline (IPOx) and 2-vinylpyridine (2VP) follow a living group-transfer polymerization (GTP) mechanism, allowing a precise molecular-weight control of both polymers with very narrow molecular-weight distribution. The GTP of IPOx and 2VP occurs via N coordination at the rare earth metal center, which has rarely been reported previously.

Organic-Inorganic Hybrid Nanoparticles via Photoinduced Micellation and Siloxane Core Cross-Linking of Stimuli-Responsive Copolymers.

Photoacid-induced siloxane cross-linking of stimuli-responsive copolymer micelles allows the synthesis of well-defined organic-inorganic hybrid nanoparticles. Two conceptually different synthetic approaches are presented, both via photoinduced cross-linking of poly(4-hydroxystyrene--styrene) micelles and via photoacid-catalyzed micelle formation and siloxane cross-linking of poly(4--butoxystyrene--styrene). The synthetic route showed intermicellar cross-linking leading to agglomerates.

Rare Earth metal-mediated group transfer polymerization of vinylphosphonates.

Recent studies have shown that poly(vinylphosphonate)s are readily accessible by rare earth metal-mediated group transfer polymerization (GTP). This article highlights the progress in this new field and advantages of GTP in comparison to classical anionic and radical polymerization approaches. Late lanthanide metallocenes proved to be efficient initiators and highly active catalysts for vinylphosphonate polymerization yielding polymers of precise molecular weight and low polydispersity.

Surface-initiated group transfer polymerization mediated by rare earth metal catalysts.

We present the first example of a surface-initiated group transfer polymerization (SI-GTP) mediated by rare earth metal catalysts for polymer brush synthesis. The experimentally facile method allows rapid grafting of polymer brushes with a thickness of >150 nm in <5 min at room temperature. We show the preparation of common poly(methacrylate) brushes and demonstrate that SI-GTP is a versatile route for the preparation of novel polymer brushes.

Role of Parent and Peer Relationships and Individual Characteristics in Middle School Children's Behavioral Outcomes in the Face of Community Violence.

This study examines processes linking inner-city community violence exposure to subsequent internalizing and externalizing problems. Hypothesized risk and protective factors from three ecological domains -- children's parent and peer relationships and individual characteristics -- were examined for mediating, moderating or independent roles in predicting problem behavior among 667 children over three years of middle school. Mediation was not found.

The role of adolescent physical abuse in adult intimate partner violence.

This study's primary aims were to examine whether a sample of young adults, aged 23 to 31, who had been documented as physically abused by their parent(s) during adolescence would be more likely to aggress, both physically and verbally, against their intimate partners compared with nonabused young adults and whether abuse history was (along with other risk factors) a significant predictor of intimate partner physical and emotional violence perpetration or victimization. In this longitudinal study, 67 abused and 78 nonabused adults (of an original sample of 198 adolescents) completed the Modified Conflict Tactics Scale and the Jealousy and Emotional Control Scales. Nonabused comparison adolescents were matched for age, gender, and community income.

Intervening processes between youths' exposure to community violence and internalizing symptoms over time: the roles of social support and coping.

The roles of social support and coping as intervening processes between exposure to community violence and internalizing symptoms were examined longitudinally among a community sample of 667 middle school students in the inner city. After controlling for potential confounders (e.g.

Physical abuse during adolescence: Gender differences in the adolescents' perceptions of family functioning and parenting.

Objective: To examine the relationship between physical abuse of adolescents and parenting by mothers and fathers and whether the association differs by gender.

Methods: Subjects were adolescents, 51 girls and 45 boys, documented by Child Protective Services (CPS) as physically abused during adolescence. Comparison subjects were non-abused adolescents, 47 girls and 48 boys, from the same suburban communities.

Physical child abuse and adolescent violent delinquency: the mediating and moderating roles of personal relationships.

Adolescent personal relationships with parents and peers are studied for their mediating and moderating roles in the effect of preadolescent physical abuse on adolescent violent delinquency. One hundred physically abused preadolescents and 100 matched nonabused classmates were studied at 10 and 16 years. Adolescent attachment to parents and verbal and physical abuse in relationships with parents during adolescence mediated between preadolescent abuse and later violent delinquency.

Pathologic adaptation to community violence among inner-city youth.

The study tests the thesis of pathologic adaptation for youth exposed to community violence, where high levels of exposure to community violence lead to increased aggressive behavior but decreased psychological distress. Four hundred seventy-one 6th graders and 1 of their parents were interviewed. The results showed, for a small but important subgroup of youth, that high levels of exposure to community violence were associated with more child- and parent-reported aggressive behavior and less child-reported psychological distress.

Normalization of violence among inner-city youth: a formulation for research.

A causal model is formulated for the thesis that in inner-city youth exposed to high levels of violence, cognitions that normalize violence mitigate affective effects of exposure while increasing risk for violent behavior, thus perpetuating violence in the very process of adapting to it psychologically. Gender differences in the cognitive normalization of violence may explain gender differences in affective and behavioral effects of exposure. Empirical studies are needed to directly test this model.

The effect of physical abuse on children's social and affective status: a model of cognitive and behavioral processes explaining the association.

This study proposes a model explaining the association between physical abuse of children and children's social and affective status as one in which children's social expectations and behavior, developed within the context of abusive parenting, mediate current functioning in these two outcome domains. Subjects included one hundred 9 to 12-year-old physically abused children recruited from consecutive entries onto the New York State Register for Child Abuse for New York City and 100 case-matched classmate nonabused comparison children. Sociometric assessments were carried out in classrooms, interviews were conducted with the children and their parents, and teachers, parents, and classmates rated the children's behavior.

Psychiatric disorders in adolescents exposed to domestic violence and physical abuse.

The relationship between abuse and psychiatric diagnoses was investigated in two groups of physically abused adolescents, 57 living in homes with interparental violence and 32 in homes without such violence, and in 96 nonabused adolescents living in nonviolent homes. Adolescents in the first group were found to be at greater risk for depression, separation anxiety disorder, post-traumatic stress disorder, and oppositional defiant disorder than were those in the second group. Adolescents in the first group also appeared more vulnerable to anxiety and depression.

Physically abused adolescents: behavior problems, functional impairment, and comparison of informants' reports.

Objective: This study, like earlier studies that focused on younger abused children, ascertained whether physically abused adolescents exhibited increased internalizing and externalizing behaviors. Relevance to pediatric practice is discussed.

Design: A cross-sectional design was used to compare the behavior of physically abused adolescents and comparison adolescents using self-reports, parent reports, and teacher reports.

A longitudinal analysis of risk factors for child maltreatment: findings of a 17-year prospective study of officially recorded and self-reported child abuse and neglect.

Objective: To identify demographic, family, parent, and child factors prospectively associated with risk for child abuse and neglect among families in the community, using data on child maltreatment obtained from both official records and youth self-reports.

Method: Surveys assessing demographic variables, family relationships, parental behavior, and characteristics of parents and children were administered to a representative sample of 644 families in upstate New York on four occasions between 1975 and 1992. Data on child abuse and neglect were obtained from New York State records and retrospective self-report instruments administered when youths were > or = 18 years old.

Adolescent physical abuse: risk for adolescent psychiatric disorders.

Objective: The present study examined whether physical abuse functions as an additional risk factor for adolescent psychopathology after other important known risk factors are controlled for.

Method: The authors recruited 99 adolescents aged 12 to 18 years directly from the New York State Department of Social Services after official documentation of physical abuse. The abused adolescents were compared to 99 nonabused adolescents matched for age, gender, race, and community income.

Parent, teacher, and peer ratings of physically abused and nonmaltreated children's behavior.

Behavior ratings by parents, teachers, and classmates of physically abused fourth to sixth graders, identified from the New York City Maltreatment Register, and case-matched classroom controls, showed substantial concurrence among informants: Parents and teachers both rated significantly more behavioral disturbance in the abused children, and peers' ratings were significantly correlated with adults' ratings, especially those by teachers. Children's exposure to spouse or partner physical abuse, which had a substantial prevalence among both child-abusing and control families, reduced the difference in disturbance ratings between children who were themselves physically abused and those who were not. Overall, we conclude that physically abused children show pervasive behavioral disturbance, in that parents, teachers, and classmates all see higher levels of behavior problems and lower levels of socially desirable behavior in them compared to their nonmaltreated peers.

The effects of physical abuse on children's social relationships.

Social behavior and peer status of 87 physically abused 8-12-year-old urban children were compared with those of 87 case-matched nonmaltreated classmates. Peer nominations and peer ratings were collected in classrooms, social networks were assessed by child interview, family variables were assessed by interviewing mothers, and behavior problems were rated by parents and teachers. Significant findings were that abused children had lower peer status and less positive reciprocity with peers chosen as friends; they were rated by peers as more aggressive and less cooperative and by parents and teachers as more disturbed; and their social networks showed more insularity, atypicality, and negativity.